View Full Version : Another Busted Piston?
In my 20+ years of ownership of my 83 C-30 6.2 dually, I've put a whopping 50K on it. it's basically a "field" truck, and is mostly used for hauling stuff, and once in a while errand running. It had 50K on the clock when I got it 9 years old. At age 12, it broke the #2 piston and cylinder. I acquired another 6.2 out of a blazer (I believe), and rebuilt it with new crank brgs, pumps, T+C, and grs, punched the cylinders +.030, and only could find "hyperutectic" replacement pistons. I really wanted forged, but couldn't find them available, and was talked into the "hypers".
Well here I am, about 20 yrs later, and 50K on the rebuild, and I believe I've busted another piston. (strangely enuff, also #2). A buddy of mine borrowed the truck a few days ago, hauling a couple yrds of compost, and while climbing a steep hill, the motor gave out. He got it up the hill to his house running, but knocking and missing. 70lbs of oil pressure at idle.
I compression tested all cylinders, and except for the #2, they all read 400LBs. The #2 is a big fat "0". I was hoping for a broke pushrod or rocker, but couldn't be so lucky. Today I removed the RHS valve cover, and all looks fine, and when cranking, both rockers open and close the valves. I can only assume the worst.
My dilemma is this. I just rebuilt the entire frt end last year, and put on new exhaust and tires. Even have acquired another cab for parts to restore the sheetmetal, along with another bed. My finances totally "suck" right now, and if it had happened a year and a half ago, I would be junking the whole pile of rubbish. The entire truck has been problematic almost entirely due to the underpowered 6.2, and fuel system in general. but I do need a truck, and hate to go to a computer controlled vehicle, that I can't afford right now anyway. I guess I'll be keeping my eyes open for another 6.2 block, and a "good" set of pistons to fix this lemon.
Not a lot of interest I guess.
So today, I decided to pull the head, and see how badly the piston is busted. Is the block scrap too? I would imagine so. When a buddy of mine was discussing the issue at hand, he asked about maybe the head of a valve may have "partially" broke away. I answered, "yeah, what are the odds of that happening"? I should be so lucky. (Which I usually am not). I watched the valve open and close, and figured if the face was busted, the stem would just pull through the guide and loosen on the retainer. But the valve was tight and opened and closed perfectly. Well, here's something to talk about. Check out the photos.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20valve%20002_zpsiyxnvzgk.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20valve%20002_zpsiyxnvzgk.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20valve%20005_zpssm6ivxvg.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20valve%20005_zpssm6ivxvg.jpg.html)
So there we have it. A partially busted face. Now, the question is, did the pieces go out the exhaust? Must have, right? There is some scarring to the piston top, but the pieces must've broken into little pieces and was evacuated. Next I'll need to rotate the eng. to BDC and see if the walls are scarred. If not, I'll be replacing the broken valve after a quick clean-up of the seat, and grinding the face of an extra valve in my possession, a quick clean-up of the head, and all the hardware, a new gasket, and back together. Also, some blending and polishing to the piston top. I wish I had the cash to go all through the motor, (like install a 6.5 turbo to it), but funds are tough right now, and this is the best I can do.
Any advice?
Yukon6.2
05-17-2015, 09:46
Looks like you got lucky.I would do the same as you are planning.
I would put the lack of reply into the not so many old die hard 6.2/6.5 drivers anymore.
I used to check in every day while having coffee,now it's once or twice a week.
Thomas
Dvldog8793
05-17-2015, 11:19
Howdy
Go out and buy a lottery ticket before it wears off...:D
If it were mine, I would do exactly as you are doing.
Do an oil analysis, if you have time.
Maybe replace the other valve in the hole as well.
There is a thread someplace here about valves and some strange breakages. It looked like something similar to your issue.
Good luck!
john8662
05-18-2015, 12:12
I agree with you and the comments above. Repair the head and put 'er back together.
Interesting picture there, you got the 6.5 gaskets on that engine, but you could because you have the plugs in the head that otherwise if not there would cause a coolant leak using 6.5 gaskets.
My impression for what it's worth on why the failures is simply RPM. A low geared dually without overdrive leaves to high RPM cruising which the 6.2 isn't really good at. Plus, factor in friend's borrowing things, never seems to end well.
You got big valve heads too btw.
J
Howdy
Go out and buy a lottery ticket before it wears off...:D
If it were mine, I would do exactly as you are doing.
Do an oil analysis, if you have time.
Maybe replace the other valve in the hole as well.
There is a thread someplace here about valves and some strange breakages. It looked like something similar to your issue.
Good luck!
Now this is great advice. I have a spare set of heads that would never hold gaskets, so I plan on "borrowing" (valves)from one to save this mill. I'll probably pop out all the valves, scrub them up, and look for defects. The other side? Well it's still on, and I'm not planning on removing it, if I don't have to.
I agree with you and the comments above. Repair the head and put 'er back together.
Interesting picture there, you got the 6.5 gaskets on that engine, but you could because you have the plugs in the head that otherwise if not there would cause a coolant leak using 6.5 gaskets.
My impression for what it's worth on why the failures is simply RPM. A low geared dually without overdrive leaves to high RPM cruising which the 6.2 isn't really good at. Plus, factor in friend's borrowing things, never seems to end well.
You got big valve heads too btw.
J
You are very observant John. I believe it was this site that turned me on to them, (6.5 head gaskets) and it appears they work well. My other heads popped quite a few over the years. Not sure when I went to the 6.5 set, before or after I changed back to my original set of heads.
And you're also right about the low gears. It's got 4.10s and hi-way cruising is no fun. But because this eng is so lacking in power, it probably wouldn't haul popcorn W/O those gears. I always keep the speeds under 55MPH, and end up driving in the right lane with all the trucks and buses. I wish I had the cash for a gear Vendors OD. And your comment about "big valves"? Doesn't impress me much. I wish they made a difference. I can't believe a small valve head would have less power.
I've had 6 6.2's. Mix of 1/2 to 1 tons.
84 Suburban 700R4 3.42 gears 31" A/T's got 24 mpg highway, couldn't pull a darn thing though.
91 Suburban 700R4 3.73 gears 31" A/T's got 21 mpg highway, pulled a 10K trailer from Alaska to Oregon, mostly in 2nd gear going 50 mph or less. I should've bought a bigger truck for that load.....
85 Suburban Turbo 400 3.73 gears 36" M/T tires (no lift), got 19 mpg on the highway. Was mostly for offroading, and did decent for what it was.
84 K-5 SM465 1-ton axles, 4.10 gears 36" M/T's 4" suspension lift. Get's 19 when I put it on the highway, same engine that was in the 85.
82 C20, 4-speed overdrive manual 32" tires unknown gears. 26 mpg highway.
82 K20, SM465, 3.73 gears, 32" tires. 22 mpg without the plow. 15 when plowing.
The overdrive is nice for MPG, but can't pull squat. Yeah they are louder without overdrive, but I also find the reliability of the heavier duty transmissions also is a huge factory when looking at these rigs. The 91 Suburban had a trans overhaul that worked great, but it wasn't cheap.
I need replace the IP on the K20, it's gutless as all get out, but plows fine. I still have the K20 and the K-5.
I keep finding these things for prices I cannot resist...
Well Mark, when I bought my C-30 over 20 yrs ago, the PO told me the truck won't go over 55, but it'll do it all day, and I'll love the fuel mileage. With 4.10s in the dually rear, it will go over 55, by I try not to let it, cause it sounds like the motor is coming unglued. (some day I'll get a tach for it).
As for the fuel mileage, I'm lucky to get 10 out of it. That's driving flat and slow, pulling nothing but my hair out. Maybe on long trips, it "may" muster 15, but I haven't really confirmed it. By the way, it has the heavy 4 spd 117 tranny, (no O/D)
Up-date: Finally making time to get this problem remedied.
After disassembling the head, I don't see any damage to the seat, so I removed a couple valves from my spare head, and ground the seats and faces of both valves being replaced. I like being able to use tooling that I own, but don't use as much as I'ld like to. For all you professionals, (all 2 of you reading this thread), here's some relics for you to either appreciate, or snicker at.:D
This is a dry face grinder that I acquired more than a few years ago. It has a patent on it from 1928, but stills runs like new. When I first acquired it, the motor drove a leather belt. It was kinda worn, so unfortunately I had to update it. All the joints are also geaseable or oilable by the lubrication stacks with springloaded caps.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1223_zpsgzdxwbrk.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1223_zpsgzdxwbrk.jpg.html)
Then, B4 I could grind the seats with my Black and Decker seat grinder, I had to square up the stone post.http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1225_zpsxcqgdgb0.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1225_zpsxcqgdgb0.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1227_zpsqdqjhrqw.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1227_zpsqdqjhrqw.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1226_zpsrnqgxgwz.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1226_zpsrnqgxgwz.jpg.html)
(Why can't I comment after my photos are installed, and I review my post?)
Once the valve seats were cut, (I only did the 2 I replaced....the others were fine), I lapped all of the remaining valves.http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1228_zpsxo1bn1iv.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1228_zpsxo1bn1iv.jpg.html)m.
And today I picked up the 6.5 head gasket, (recommended by this site), and the other gaskets needed to complete this job. Unfortunately the valve stem O-rings had to be ordered, so I 'll be waiting till tomorrow for assembly.
Now I need to finish washing the dishes.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1222_zpsfuveiasq.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1222_zpsfuveiasq.jpg.html)
Dvldog8793
06-02-2015, 19:58
I had a south bend tool room lathe in my shop for awhile that was belt driven. Many of the older machines were, kinda the KISS theory. Our country was built with belt driven machinery and assembly lines. They are self clutching and simple to repair.
11 years ago I bought a new air compressor. It had 7.5 HP motor with grease zerks....soooo....I greased them. Well in about 2 years all the magic smoke escaped from the motor. tore it down just to look, and the zerks went nowhere. I was pumping grease into motor housing and it shorted out the contactor. I called the compressor company and they said it had sealed bearing and they were just using the zerks to plug the holes and that nobody greased anything anymore so it never was a problem....in other words it was my fault:rolleyes:. My Bridgeport is at least 40 years old and is still tight and runs true...it uses about a quart of oil a year.
Old school is better IMHO.
Good luck with the engine!
More Power
06-03-2015, 11:08
Be sure to measure valve stem protrusion on the reworked valves seats and check stem clearances with the rockers installed. Looks like you're doing a good job.
Jim
Thanx guys, the guides are nice and tight, so I think that'll be OK.
I was curious if could get an opinion? These heads don't have any intake seals, only the valve stem O-rings. I have some scrounge rubber umbrella seals, that I may see how they fit on those bosses. But they don't have any retaining method like the newer ones, clamped with wire or a band. Does anyone see a benefit, or hindrance to using these?
P.S Never mind, I just checked them, and they don't fit anyway. Guess I'll be installing valves, W/O intake guide seals. didn't need them B4, guess they won't get them now.
So far, things aren't lookin too good. After redoing the replacement valves, lapping them all, and drip testing the seats with gas, (no leaks apparent),and reinstalling the head with a new gasket, I might as well have just left out both the valves. Doing a quick compression test B4 fire-up, the same cylinder could hardly pull 50lbs. But the other cylinders that were pulling 400, now only showed 250-300. Not sure if the walls got dried out from being stuffed with rags while gasket scraping, the battery wasn't spinning the motor fast enuff, or a combination of both, but I decided to fire it up anyway. Once I did, the same cylinder is still missing. I had the engine running with the compression gauge on it, and a couple times there was compression, but it just bled off. I don't get it. Now I need to pull the valve cover, and see what kind of valve action is going on, and do a leak down test, and see if I can hear a leak. I didn't see any noticeable cracks in the head, block, or piston, so I'm totally stumped. Here's a pic of the polished piston top. It may be ugly, but it shouldn't be leaking.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/DSCF1234_zpssjqyhqra.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/DSCF1234_zpssjqyhqra.jpg.html)
DmaxMaverick
06-09-2015, 07:23
This. Did you measure? It isn't the guides in question. Fortunately, this can usually be corrected w/o head removal, if necessary.
Be sure to measure valve stem protrusion on the reworked valves seats and check stem clearances with the rockers installed. Looks like you're doing a good job.
Jim
To be honest Dave, I didn't. I realize if the valve sinks lower, it'll effect the valve train geometry. But the amount that was removed was minimal, so I was "hoping" this wouldn't be too much of a factor.And because the lifters are hydraulic, there is some leeway to be had. Also, the springs were shimmed, so I don't believe the pressure would be influenced too much by it either. As mentioned before, this is a field truck, and sees minimal mileage a year. But of course I do want it to work. Thanx for your input.
Unfortunately, the story doesn't get better.:confused:
Today didn't bring any better news than yesterday.
I removed the valve cover, hoping to see a pushrod off it's seat, or (as mentioned above), the intake valve being lower in the seat, maybe on the heel of the cam, the valve being longer is now not seating. At first, the intake pushrod was tight to the feel, but once I rotated the eng. to the compression stroke, (intake valve just closed), both the intake and exhaust pushrods were loose and rotating freely.
Next came the leakdown test. To sum it up, with 50lbs of air pumping in, 45lbs are going out. with the intake off, and the port staring me in the face, there's isn't any blowing out there. by crawling under the truck, and listening to the exhaust pipe, I don't hear it there either. Nothing in the radiator, even tho there isn't much water in there at this point, but when I stick a 3/4" heater hose down the oil filler tube, that's where I hear it. Which means it's getting into the crank case. but how?:confused:
Now in the scenario of my 1st motor, I would expect this. Here's a couple pix of what happened to my "1st" engine, that was in the truck when I bought it. After a years worth of driving, and less than 60K, this is what happened.http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/broke%206.2_zpswgypeaym.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/broke%206.2_zpswgypeaym.jpg.html)
Don't let those 2 pictures above confuse you, that's not the engine in the truck now.
My question is, if the valves are sealing, and there isn't any holes in the cylinder wall, or piston top, could pieces of the busted valve have gotten between the piston and wall, and broke the rings? But not leave any scoring on the walls? Could there have been a hairline crack in the block or head, that's not visible to the naked eye, but opens up under a compression test, or leakdown test? I don't get it. Unless someone talks me into filling the thing up with water, and driving it a few, and see if some oil gets back up on the walls to seal, then I guess I'll be pulling the head back off.
I "really" want to keep this truck, (even tho at this point it's a total rust bucket), and people are telling me to junk it, and count my losses, but I hate giving up on something that does fine for me, just because of a little...er..."hic-up"? I know it's old, but I'm not far off either, so we make a good pair.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/leakdown%20test%20001_zpsg8blerya.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/leakdown%20test%20001_zpsg8blerya.jpg.html)
john8662
06-09-2015, 13:44
New gasket and sitting now lower compression on 3 holes and one still dead? Naw, should still make the correct psi with correct cranking speed as it did before dis-assembly.
Doesn't sound like your gasket sealed, 25, 50 ft lbs then 90 degrees? I didn't see any lines on your bolts, maybe you used a torque angle wrench?
Too much Dowel protrusion causing head to not pull down onto block?
Fel Pro or Victor gaskets? Victor at standard thickness is thicker torqued down than a Fel-Pro at standard thickness.
I'd think that if you had ring damage due to debris, that you'd have signs on the cylinder wall. But, a possibility none the less.
I don't think it's your valve train, you're seeing the valves open and close rolling the engine over? No collapsed lifter right?
Keep plugging!
John
Hi John,
I used the 6.5 fel-pro gasket, and the TTY bolts were new the last time I did a head gasket change many years ago. So they do have a couple torques on them. And the method of torque is the new "up-dated" version this site recommended years back. As you said, 20-55, then 90*. I don't see the new gasket installation being a problem, (and yes, the dowels were contacted properly). And once again, the sound of bleeding air is prevalent through the oil filler hole (crank-case) only. If the head gasket was leaking wouldn't it bleed out externally, or between cylinders? Also, the lifters don't appear to be collapsed. I watched the intake open and close, but didn't go around to the exhaust. But if a lifter was collapsed, I wouldn't think it would be relevant to a leakdown test. If the lifter was stuck in the "up" position, then a valve would be hung open, which would cause a failed test, but both valves I've proven to be shut, during the Leakdown test. I even backed off the rocker shaft for those 2 cylinders, so they wouldn't be effecting the test. Same results. "Huge" leak on the leakdown test, with both valves shut.
It seems to be a "no-brainer". valves are closed and sealing, piston doesn't have any hole in it, doesn't "appear" to have any crack in the head, (combustion chamber), piston, or cylinder wall, and there's air blowing into the crank-case. It would seem the only thing left is the rings. I'm wondering if I could pull the one piston, with the engine sitting on its mounts. Don't know if I could get the pan off.
john8662
06-09-2015, 17:12
If the gasket didn't seal, you could get combustion chamber gasses in the crankcase. A leak into the area where the pushrods are or the passage for oil drain back to the block.
You should not re-use the TTY bolts, they have already been stretched when used once.
Not sure about getting the pan off with the engine sitting in it's mounts in a C30. I can't speak from experience as the units I have removed pans on in chassis were both C10's. These both required jacking up the engine to have the clearance to get the pan off.
Starting to seem like cracked piston. That ding about 10 o clock may have a crack that runs down the side of the crown, or a ring land.
John
I understand the reasoning of the TTY bolts, John, and I'm sure a new set would be the "preferred" method, but can you honestly tell me, that by re-using them will cause a blown gasket right off the bat, and cause "zero" compression in the same cylinder that was defective before, and not cause the other 3 to miss? I'm not trying to sound sarcastic, I'm honestly asking. And you're right about the area open to the crankcase. The possibility does exist. I believe my next course of action, is to remove the head, (again), and make a plate to cover the top of the cylinder, and do a leakdown test to it. If I use some thick clear plexi-glass, and the gasket, maybe I'll check it as is, then squirt some oil into it, and re-test it, and see where the oil leaks. Just a thought, before I go yanking the piston. Thanx for your thoughts, John
http://i1206.photobucket.com/albums/bb453/tajoe/tumbleweed_zpse67943d5.jpg (http://s1206.photobucket.com/user/tajoe/media/tumbleweed_zpse67943d5.jpg.html)
trbankii
06-12-2015, 06:11
The whole point of a TTY bolt is that it is for a single use.
Torque to Yield Bolts (http://www.freeasestudyguides.com/a1_4.html)
Last line - "At this point the bolt has changed its form, and if loosened or removed, it must be replaced with a new torque to yield bolt."
Once they’ve been deformed, they’re not going to give you the proper torque - they’re in plastic deformation and will just continue to stretch.
OK TR, so are you saying to cure my dead #2 cylinder, all I have to do is buy a new set of head bolts, and my compression will be restored? For that matter, because the others cylinders are good, then realistically I only need to replace the 5 around the #2 cylinder.
trbankii
06-12-2015, 14:30
I’m not saying that using TTY bolts are going to solve all your problems.
I am saying that using used TTY bolts will not provide proper clamping pressure and likely cause you problems.
Point taken TR. I'll keep posting once I get time to continue on this dilemma.
trbankii
06-13-2015, 07:57
I’m not trying to be a smarta** - just that I know how frustrating it can be to diagnose some of these random issues and adding known problems into the mix just makes it that much more complicated.
I hear ya, and I'm not trying to be ungrateful for your opinions. If I were Donald Trump and could afford to do everything by the book, I'ld take it to a garage and let them do it. So if there are times I can cut corners to save a dime, (which won't cause undue grief), then I'm all for it. The problem I need to determine, is which ones are important, and which ones aren't.
Just a quick up-date. I was showing my attempts to a buddy, and figured out on my leakdown test, I was reading the test incorrectly. It's been quite some time since I've used it, and was mentioning the test was showing 95% leakage. When in fact, as you can see in the tester picture above, when I pumped in 50lbs on the inlet gauge, and the other gauge was reading 45lbs, that actually correlates to 5-10% leakage, and "not" 95%. It doesn't make sense to me, but in fact is true. When I plug my finger on the end of the hose to the cylinder, the right gauge goes to 50lbs, same as the left gauge which is regulated. When I uncover the hose end, the right gauge goes to "0", as all the air is rushing out. And the sound of rushing air into the crankcase? The sound is the same when I put the leakdown tester on the #4 cylinder, which testes fine on the static test.
But I'm still stumped in that if the leakdown test is now showing 5-10% leakage, why is the static compression still showing less than 50lbs in that #2 cylinder, and the other cylinders are reading fine.
Just a new thought thrown into this baffling dilemma.
trbankii
06-14-2015, 09:44
Are you sure that the leakdown tester is sealing fully? Wouldn’t be the first time that the tester is the problem.
Yes sir, the leakdown tester "and" the compression gauge are snug in their connections. Remember my correction. The leakdown test I was reading backwards, and is "not" leaking 95%, but only about 10%. It's the compression test that's coming up less than 50LBs, when the cylinder next to it reads fine. And once, when the engine was running, it was definitely missing, on the #2 cylinder. I watched the compression gauge read normal for a few seconds of running, then dropped 1/2 way, started to climb again, then fell off to almost nothing. All in about 20 seconds of running. And I agree with the potential of a faulty gauge. At 1st I thought it was the gauge, so I tried a different one, and it also read low on the #2 cylinder, but not on the #4.
john8662
06-16-2015, 13:24
Maybe roll the engine over while doing the leak down test. If you have a broken ring it can seal and then leak.
J
There's an easy idea. I'll give it a try, and let you know John.
By the way, when I do the leakdown test, supposedly the motor cold spin over,(under pressure) if the piston is slightly on the downstroke. But this has never occurred on this engine. I'm assuming because the other cylinders having good compression are holding the piddly 50lbs back.
Update to my "lack of progress". I made a plexi-glass plate to P/T the cylinder (s), and with all the data I collected, (with many tests), and problems with tooling, I've come to the conclusion I acheived "zilch", Nada, nothing. All data seems to be "inconclusive". All actions and reading were "bad", even on the good cylinders. But what is bad? I don't know of anyone P/Ting a 6.2 with a leakdown tester, and a plexi-glass plate. I have some you-tube videos I can post if anyone cares.
So at this point, I had 2 options. Pull the piston, which is more work than I want to do if not necessary, or install "new" TTY bolts and head gasket to see if that could be an issue. That's what I just accomplished today. Scoured the deck and head surface to brain surgery clean, installed new head gasket, and "meticulously" torqued and degreed in sequence per the manual with brandy new TTY bolts. And the results? Not a bit of difference. Nada. Still no compression on the #2 cylinder. The #4, altho low, still shows some compression at 200. so I know the gauge is reading.
Now, If I can keep myself from stacking TNT in the 8' bed for a fireworks show, I'll be pulling that #2 piston out. (When I feel ambitious enuff to face it).:mad: (Happy 4th of July)
Dvldog8793
07-05-2015, 16:51
I am betting busted ring/s
Maybe not busted, but rather all stuck in the grooves with carbon.
I have yanked 6.2/6.5 apart that the rings took an act of god to get them out of the grooves.
Yank the pan and get the offending beast out for a look.
If the rings are stuck, then it's time to do a ring job.
Thanx for the reply Robyn, but as I mention before, I rebuilt the eng. less than 50K ago. I've always kept up on oil changes. I throw away clean oil. The engine ran fine till the valve busted. That's when the compression went away. On that #2 cylinder only. I'm pretty sure there isn't any carbon that clamped onto the rings when the valve broke. But you're right. it looks like I'll be needing to pull the piston to see what went on in there. Couldn't get off with an easy valve job, could I.
DmaxMaverick
07-06-2015, 15:54
Are the heads still oriented the same? Have they been swapped at any time? Maybe, before pulling the engine, swap the heads (left to right), to confirm the problem is the cylinder. Gaskets and bolts can be reused for compression and leak-down testing.
DmaxMaverick
07-06-2015, 16:01
Also, consider the possibility of buggered glow plug hole threads or seat on that cylinder.
Are the heads still oriented the same? Have they been swapped at any time? Maybe, before pulling the engine, swap the heads (left to right), to confirm the problem is the cylinder. Gaskets and bolts can be reused for compression and leak-down testing.
I do have an extra head I could try for G/Ps. Not a bad thought, Dave. Anything to keep me from pulling a good piston. (I know, I'm just procrastinating the inevitable.)
DmaxMaverick
07-06-2015, 20:22
It's Greg, actually. (no worries)
If you have another head for testing, you don't really need a full install. All you are looking at is compression and cylinder integrity. I wouldn't even install the rockers or pushrods. If you do only the leakdown test, it should tell a tale. Start with the piston TDC and repeat for 4-5 positions down to BDC. I would even go so far as to duct tape (or RTV) the valves, to ensure zero leakage goes that way.
It's Greg, actually. (no worries)
If you have another head for testing, you don't really need a full install. All you are looking at is compression and cylinder integrity. I wouldn't even install the rockers or pushrods. If you do only the leakdown test, it should tell a tale. Start with the piston TDC and repeat for 4-5 positions down to BDC. I would even go so far as to duct tape (or RTV) the valves, to ensure zero leakage goes that way.
Good idea "GREG", (Sorry), and someone at work recommended the same thing today. Maybe it's "karma" or maybe I'm a glutton for punishment, but I really need to extinguish "all" possible or potential components, before ripping into the bottom. i really can't "visually" see any defects in the head or valves, but maybe it's hiding. I don't know. I'll keep you posted. Thanx for the advice, "GREG". :)
So I did remove the reworked head, and dumped the used head on top of the 1 time used gasket that stayed in place, until I tried mounting the used head and knocked it out of place a couple times. But once I was confident I had the head and gasket doweled in, I took my old bolts and ran them down with a 1/2" impact gun, and then grunted them tighter with a 1/2" breaker bar.
My 1st 2 tested consisted of a leakdown test on the "bad" #2 cylinder, and then the #4 (good) one. After those tests, I did a static compression test on both of those cylinders. The results were consistent on all 4. Absolutely nothing. 50lbs in both on the leakdown, and no backpressure on "either cylinder.100% leakage. On the compression test, the needle didn't even pulse for a second, on either cylinder. so I can assume I boned up putting the secondary head, and didn't get it seated? Or during all my testing, I've destroyed the ring seal on the entire engine? The faster I run, the further behind I get.
Finally I can honestly say, the pan will be coming off, and at least "1" piston will be coming out. (Here's a pic of the secondary head.)
Dvldog8793
07-11-2015, 15:37
Howdy
IMHO....I would pull the engine.
If the #2 piston rings look normal when I pull it, the truck will be parted out. I won't be doing anymore work to it. I can honestly say, I got my monies worth out of it these past 23 years. The body is shot, and the only reason I did the frt end last year, and bought body parts to clean it up, was because the motor was still running fine, and didn't have a ton of miles on it. But if I can't locate this compression leak, (and because next year I'll be 60), I'm tired of working this beast, and it will go to a better place. "However", if the rings "are" broke, causing my problem, I'll have a new restored vigor to keep it going. Time will tell.
john8662
07-13-2015, 10:55
Take the head to a machine shop and have them go over them, check height, etc and just make sure there isn't something missing there. Easier than pulling a piston, but does cost some dough.
J
The valves aren't leaking John, and I even tried another head, as mentioned above. The last course of action is to clarify the piston and rings by bench inspecting. (Which I just pulled out a couple hours ago.). It's late, so I'll report back tomorrow with some more photos.
Well, before I report the findings, I want to confirm a question about oil pan removal. In an 83 C-30, the pan will not come out while sitting on its mounts. I had to pull the starter to access and remove the RHS mount bolt, and disconnect the oil cooler lines at the LHS rear of the engine for added clearance. And with a couple 2 bys on my floor jack, I raised the eng. up enuff to stuff some wood under the mount brackets, and then set it down. This gave "just enuff" clearance to slide the pan out rearward.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20010_zpsxqu8csci.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20010_zpsxqu8csci.jpg.html)
Now for the piston removal. The #2 rod throw is directly above the crossmember, and made the rod nuts extremely difficult to ratchet in those tight confines, especially considering how much torque is on them. But once I got them and the piston out, this is what I found.http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20003_zpsqvdmd8ia.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20003_zpsqvdmd8ia.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20001_zpse9n0qmi6.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20001_zpse9n0qmi6.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20002_zps8n92wacz.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20002_zps8n92wacz.jpg.html)
I believe Robyn called it right, (as usual), and mentioned stuck rings due to carbon. I'm not sure it was carbon, or the trauma the piston experienced due to the busted valve smashing against the piston assy, or a combination of them both, but the 2nd ring is stuck in its land. The top and oil ring are fine, and the 2nd isn't broke, just jammed. So is this enuff to cause a cylinder that usually has 400lbs static compression, to have next to nothing? Wouldn't the top ring hold "something"? Does the 2nd ring back up the top ring this much? I'm elated to find something, but would've been more excited to see "both" rings stuck.
And because this is a "low budget" repair, I decided to clean things up a bit, and ponder the results. 1st I carefully removed the rings, (which all came out easily, including the stuck one)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20006_zpsdfbwlhds.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20006_zpsdfbwlhds.jpg.html)
Then I scraped out the crap in the lands with a groove cleaner
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20007_zpsq0fvzxzb.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20007_zpsq0fvzxzb.jpg.html)
And finally soaked the piston in the dishwasher
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20008_zpsuhwvoncm.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20008_zpsuhwvoncm.jpg.html)
After some final polishing, I put the rings back on, and all looks normal
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20011_zpsjfmi043g.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20011_zpsjfmi043g.jpg.html)
I know these 2 pics of the bore won't show too much, but I figured I'ld toss them out there, in case someone wants to see. My next step will be to run a honing stone down it, and break the glaze.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20004_zpsitvbyadw.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20004_zpsitvbyadw.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20005_zpsdpljl6kh.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20005_zpsdpljl6kh.jpg.html)
And the bearing halves look fine also, so they'll get put back into place. I can't see buying new, to replace serviceable components, for only "one" cylinder.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20piston%20009_zps1cjkkfvn.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20piston%20009_zps1cjkkfvn.jpg.html)
So there it is. Can we assume that when the exhaust valve broke, it pounded the piston to stick the "2nd ring only", making all the compression go away? And once the exhaust valve was remedied, it had "no influence" what so ever in the compression test, due to the ring being stuck in its groove? Or was the top ring also stuck, until I removed it, and magically "popped out" when I removed it? Can all the glazing on the cylinder walls being run dry through the testing process also be influencing the test results? So many baffling questions, and the only critical find in my eye was the broken valve head. Unfortunately, it wasn't the only problem. I think I've covered all bases, and will end up sticking it back together, to see if the leakdown test, or compression will improve. Or if the masters chime in, and have any alternatives, short of dumping the whole mill, and starting over with a clean slate, (which I can't afford at this time).
DmaxMaverick
07-17-2015, 08:24
I'm not buying it, fully. One functional ring, even only the oil ring, surely wouldn't allow zero resistance. How do the rings fit in the bore (w/o the piston)? What are the compression ring gaps?
This far in, I definitely wouldn't reuse the rings, and likely not the piston, either. I think you have more wrong than just one stuck ring. If the valve interference, somehow, caused the ring to stick, the piston is damaged or broken, for sure. Even if you don't see it.
Dvldog8793
07-17-2015, 11:12
On a different note....I notice the Muscle Car parking and also the GTO sign in the back ground....do you have a Goat?
I'm not buying it, fully. One functional ring, even only the oil ring, surely wouldn't allow zero resistance. How do the rings fit in the bore (w/o the piston)? What are the compression ring gaps?
This far in, I definitely wouldn't reuse the rings, and likely not the piston, either. I think you have more wrong than just one stuck ring. If the valve interference, somehow, caused the ring to stick, the piston is damaged or broken, for sure. Even if you don't see it.
I can appreciate your opinion Gregg, and I don't see how a second ring could do this either. But the thing is in my hand. It worked perfectly till the valve broke. All I see visibly is dings on the crown, caused by the failure. So it wouldn't be a typical "worn skirt" or excessive ring gap, to cause the lack of compression. I would expect something like rings coming out in pieces, or cracks or broken pieces of piston skirting, or even the piston crown separating from the piston sides. And I really won't buy just 1 set of rings or 1 piston, if I can't find any evidence of them being defective.
Next I'll measure all the ring and piston clearances, and maybe spray some dye penetrant on the piston, to check for a crack, and if all looks "normal", then I'm gunna hone off the glazed wall, stuff the piston down the hole, (W/O installing it to the crank) and put my plexi-glass plate over the top, to do another leakdown test. It won't require oil pan installation, or a head install, just to see if I can improve on that reading.
I know it all seems like an "excessive waste of time", and this isn't the way to run a business, but my main objective is to get this thing running W/O an unnecessary amount of cash spent. And seeing I've been in the overhaul business for about 40 years, I know things don't need to be "new" to be serviceable. I hope you guys don't take my methods personal, cause I do value everyones opinion, even if I don't act on them the way some of you would want. But if nothing else, you got to admit, it's "entertaining".:rolleyes:
On a different note....I notice the Muscle Car parking and also the GTO sign in the back ground....do you have a Goat?
You're very observant, aren't you 'Dog? I've had a few Goats in the past, but unfortunately am not able to acquire even a condition 5 car at this point. They've been my favorite for all my years, but only have memories now. I do have a couple T/As, (73 and 84), and both are project cars. Will probably end up selling the rougher one (73) much as don't want to. But the 84 needs less bodywork, and would be easier to accomplish and is on my bucket list. Don't think I'll be able to do both, with what time I've probably got left. Especially seeing I've been spending most of it trying to keep my DD and this truck running. But I'm sure you can relate.
And the quest continues. Today I broke the glaze off the cylinder wall, and stuffed the piston back in, (temporarily?). There is some slight wear at the top of the bore, but it looks worse than it is.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20004_zps639jefai.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20004_zps639jefai.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20005_zpsou8ret3f.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20005_zpsou8ret3f.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20006_zpslgj311cm.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20006_zpslgj311cm.jpg.html)
By installing the piston as is, what it'll prove to me, is if a stuck 2nd ring will cause these low readings. (I don't believe it, but it don't hurt to check). I think my plexi-glass fixture will only have one more test left in it. Because it's 2, 1/4" plates stuck together, every time I have to remove it, the RTV causes it to break a little more. But there is enuff material around the bore to hopefully seal. I'm letting it set over night, to make sure the RTV hardens completely.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20007_zpsahfcc9e9.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20007_zpsahfcc9e9.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20008_zpszlgtbv5e.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20008_zpszlgtbv5e.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20009_zpsvosocmfg.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20009_zpsvosocmfg.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20Piston%20install%20010_zpsb1aybxum.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20Piston%20install%20010_zpsb1aybxum.jpg.html)
DmaxMaverick
07-18-2015, 18:58
Good luck, be careful, and remember.... That plexiglass shouldn't hold the pressure the cylinder should. I'm sure you know that, but if the repair was successful, it could have a different, bad ending. Looking forward to a positive report.
Thanx Gregg, (I think). If the rings hold, are you saying the sealant will blow out at 50lbs? I'ld like to think the little bit of air at that pressure, both will hold. If I see about 20% or less leakage, Ill be ecstatic. If it still shows almost nothing on the gauge, (and I'm confident the fixture isn't blowing out), then I'll try new rings. But I'll still question why they held pressure until the valve broke. I'm sure the other cylinder rings are in the same condition.
This morning I bring some good news, and some not so good.(Naturally).
The good news is the test was very accurate, and I'm confident of the results. The bad news is it was what we expected. The fixture did well, in that it didn't leak oil. But it did push the oil past the rings. At 1st I did it at the top of the cylinder, where there is some minor wear. I was able to pour a minimal amount of oil on top of the piston, and it did push out the bottom. once I got the pressure to 50lbs, I could stick my hand into the bottom of the piston bore, and feel the air leaking past.
Then I rotated the crank a few degrees to get the rings off the shiny spots, poured in more oil, (to the top of the bore), and retested. I put a rag on the crossmember to see the oil, and it was all there.
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20PT%20001_zpsuhm3nzjf.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20PT%20001_zpsuhm3nzjf.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20PT%20002_zpsav6tpmpl.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20PT%20002_zpsav6tpmpl.jpg.html)
http://i1206.photobucket.com/albums/bb453/tajoe/83%20duelly/6.2%20PT%20003_zps08gkx7wm.jpg (http://s1206.photobucket.com/user/tajoe/media/83%20duelly/6.2%20PT%20003_zps08gkx7wm.jpg.html)
So I'll be taking the piston back out, and give it another groove inspection. These rings have a strange shape, in that they're not "square" or rectangular, but beveled both top and bottom sides. I wonder if the leakage isn't going past the diameter, or the end gap, but rather the inside of the ring and groove. Because the top and bottom surfaces aren't "loaded" in the groove, (on a P/T) maybe this is why the air is leaking out? On a static compression test the ring is shoved against the top of the ring land on the down stroke, and pushed up against the bottom on the upstroke. On this test, the ring is sitting stagnant.But I've done plenty of gas motor leakdown tests, and they work. I've never done one on a 6.2, or one with a beveled top ring. Not sure if it'll hold. I don't remember if I tried a leakdown test on the other side of the block, that I didn't remove the head from, and had 400lbs static compression, before I pulled the RHS head. I should give it a try for GPs.
If I don't see anything unusual in the ring groove once I take off the ring again, I'll probably end up doing as Gregg recommended, and buy another ring set. I see Robyn posted a link to a site that'll sell a set for 1 piston, so I'll probably be giving them a call. I can't believe the mark-up on rings now-a-days. Even our Napa can't supply "rings only", you have to buy a complete overhaul set. It's a conspiracy I tell ya.
I've spent an hour trying to find a single set of rings, but a .020 oversize seems to be as rare as an honest politician. And some of these websites have limited info, and they don't make contacting them easy.
I was fortunate enuff to find out Hastings carries these rings in +.020, in a single set, so I ordered them. No great bargain, but beats buying a whole set.
We'll see how they perform when they arrive in a few days. Got my fingers crossed, cause I'm running out of ideas.
'86 Dooly
08-01-2015, 19:05
Bought a Beautiful 86 Duelly with 30,000 on a 2005 rebuild.Got a 400 turbomatic transmission and it loves 70-75 Mph. Don't know the mileage but seems ok.
Now that is some serious truck you got there Dooley. Talk about your "KingCab".
That is one sweeeeeeeeeet ride
I love that body style.
OK people, sorry to be away, but I had some computer technical difficulties, and have fallen "way" behind in my up-dating. To do a quick recap, an exhaust valve broke damaging the #2 cylinder, and refreshing the heads didn't fix the problem.
So next I wanted to prove the rings defective with a leakdown test, but testing was sketchy to say the least. But I had enuff info to warrant pulling the piston, which I did, and you saw the stuck 2nd ring. I did get a single set of .020 rings from Hastings, and put them in. Here's a quick video of the results. It was actually the 3rd test, and my blooper was, the compressor valve was shut off at the time of filming, and the seal blew on the plate because of the amount of testing, but you can still see the results.
http://www.youtube.com/watch?v=3FIFATByon0
http://i1206.photobucket.com/albums/bb453/tajoe/tumbleweed_zpse67943d5.jpg (http://s1206.photobucket.com/user/tajoe/media/tumbleweed_zpse67943d5.jpg.html)
Well, seeing this thread is a dead end, and doesn't seem to draw any interest, I'll end it saying that when the exhaust valve broke on the #2 cylinder, it somehow upset the ability of the rings to seal, no matter how many attempts at cleaning and lapping them into the ring grooves. Even tho they weren't broke, there wasn't any static or leakdown test that would show them to seal even the smallest amount. Once I changed the rings to a new set, all was well.
So my goal was to prove what was broke, "really" was broke, and change "only" what was broke, and I did accomplish this with minimal cash expenditures, and for less than a couple hundred bucks, I got it back and running. I wish it didn't take so long, but I didn't spend all my waking, hours on it either. As mentioned B4, the truck is old and beat, but the motor has less than 50K on the rebuild, so I thought it was worth what little I did to it. I now have my "dump" truck back in service, and it was very inconvenient with it down. Now maybe I can move fwd on the cosmetics.
http://www.youtube.com/watch?v=s_sIrweVir8
trbankii
08-07-2015, 15:01
The lack of response is likely due to nobody else having any similar experiences. But it is good to hear that you’ve found a solution and will have your truck back up and running!
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