View Full Version : New to 6.2
I've been a fan of Chevy trucks for many years, owning versions from a tricked out 65 up to my current daily driver which is a '02 DMax 2500HD. I also have an 88 K5 "rock crawler" and general off road expedition vehicle with 350 TBI. My daughter has been driving it until she can afford something better, but the gas is killing her. I've been thinking of converting it to diesel for years, maybe a 4BT if/when I ran across a decent deal. Then 2 weeks ago a friend turned me onto an 85 C10 base model (not even AC - in Phoenix!) with 6.2. When I went to look at it, it appears to be an original low miles unmolested example. It still has all the plastic intake stuff in perfect shape, even the jack, stickers, everything is there and intact almost like it sat on the lot in 85. It's even relatively clean, but with enough grime to indicate it's not been washed down, and I do know enough to understand how rare that is for a 6.2. Trucks also in remarkably good shape all around. And the really odd thing, it's a short bed step side with SM-465. And it's an AZ truck, so no rust.
I may eventually put it in my K5, but my 20 yo daughter loves the full size trucks. She's in college for several more years, and it's unlikely she'll find anything better cost of operation for less money, so I'm now planning on putting it back on the road. It's been setting for about a year, so dead batteries. And I didn't want to crank it till I got the fuel system cleaned out (1/2 tank to dispose of), so I don't know much about it. The story goes that they had just traded for it, and it had starting issues, so they put in glow plugs and a controller. Also looks like a fairly recent fuel pump with tamper marks. Also has new battery cables and other signs of someone taking care of it.
Anyway, they (say they) got it running "good", then shut it down. When they started again it cranked but pumped out "gray smoke". Apparently indicating unburnt fuel. Other things came up, so they never got back to this one, and now it's mine.
Obviously I'll be reading here over the next few day to educate myself a bit. I've never before owned or worked on a 6.2, so lots to learn. My main point in posting was as "introduction", and to see if the tale I was told rings any bells for anyone as to what is wrong. Hopefully by the end of the weekend I'll have the tank emptied, out, and cleaned. And I've got a new fuel filter (even though the one on it looks new). Depending on what I find in the tank, I may even pull the lines to empty/clean as well. That and new batteries from Sam's should get me to a point of trying to get it cranked to see what I've got...
john8662
09-16-2011, 14:55
Is it worth just keeping the truck as-is? Sounds like a rare truck to me.
6.2L Diesel, stick shift, single cab short bed (step side even). Not common at all. Possile someone stuck the step side on it and that it was originally a fleedside. I don't think that GM made a step side in that body style other than 1982 models.
pictures?
Welcome to TDP forums!
We are now considering keeping it together for her to drive. It should get maybe 20 mpg, much better than the 9-10 my K5 gets, and more suitable to daily freeway use than the lifted K5 on 35" tires.
And I have no idea about the bed. All I can say is that if it didn't come on that truck, it came on one about the same age and color. Both cab and bed are white. The bed looks to have a bit more gloss than the cab, but they are weathered about the same, and both show some signs of "spray can touchup", probably covering sun burnt paint (probably never waxed, and Phoenix sun is harsh) as there is no evidence of damage anywhere. Just based on the details, if they didn't come together originally, I would say they've spent at least the last 10-15 years together.
Tonight we drained the roughly 8 gallons that was in the tank for the last year or more. Came out clean and clear, though almost devoid of "diesel aroma". So I decided not to drop the tank for cleaning, or run the lines clean. Added 5 gal of fresh fuel and moved on.
Next, Dropped in a fresh pair of 750 cca batteries and lit 'er off. Took a bit, with a few reheats of the glow plugs, stuttered a few times, then finally caught. Smoked and chugged a moment, then settled down and ran pretty nicely. I was frankly stunned, my luck is never that good. And of course, it's not that good this time either. Moments after my brief period of elation, the idle dropped at least 100 rpm, it stared lopping (not really missing, but not running smooth), and belching out the gray smoke the previous owner described.
Oh well, at least I'm back to the point they abandoned it way back when. Man that sucker rattles, spoiled by my DMax. Hopefully it will be much better when it gets up to full temp.
Any of you with more experience got any idea what might do what I described. My first thought is injector pump, and that's about the time it would (I think) have dropped off high idle? Second thought is injectors, but why the erratic change? I'll be reading tonight and tomorrow morning to try to learn which way to go, but any help would be much appreciated. Thanks...
DmaxMaverick
09-16-2011, 23:05
Sounds like retarded pump timing. Once the HPCA (internal advance when cold) shuts off, the timing retarded. Try advancing the pump about 1/16" on the timing mark at a time. Note: The pump turns opposite the crank. Many people mistakenly time the pump while the engine is cold. This makes for hard starts, then smooth running, then crappy/smoky running once it warms up. This time of year, the HPCA should be engaged for only a few minutes before it shuts off. In winter, it can stay on for 5-10 minutes. Similar to an automatic choke.
I agree with Maverick on the timing issue.
My gut feeling says that the injection pump is probably in poor shape and that the injectors are likely a tad sour too.
When the injector POP pressure falls off too far, the fuel slobbers into the precups and burns with a lot of smoke.
Bumping the timing up some may help for the short term,, but it sounds like things need a refresh
Getting that IP freshened up along with the injectors and that little critter will likely run like a top and get great mileage.
I had a 3/4 ton Burb 4x4 back in the late 80's that would do 23-24 Hwy
This was a stock 2500 4x4 with stock sized 16" tires 4.10 gears
Hard to believe that a tank like that could get that sort of mileage.
The smoke is definately unburned fuel and the whole scenario is common with a failing IP.
Doing the injectors and the IP will get the job done.
Be sure that the fuel filter is in good order too.
This is not a tough job to do.
If you have this IP rebuilt then just reinstall it and align the marks on the IP and the cover.
If you are in need of a complete rundown on the R&R procedure just hollar and we can do a start to finish step by step.
Pretty simple really, just time consuming is all.
john8662
09-17-2011, 09:36
awesome truck man.
Ditto on the timing, sounds like it need to be advanced.
J
Well, I adjusted the timing. When I started, the pump marks were almost lined up, with the pump mark just a little off toward the driver's fender. I read somewhere that to advance, you rotate the pump top toward the passenger fender. Aha! It's setup retarded! So I set about to adjust it for ~1/16" advanced. Boy, it really didn't want to move. Looks like there is maybe a special spanner meant to do this with?
Anyway, I managed to get the pump mark a bit less than 1/16" left of the mount mark (pump mark closer to passenger fender) without too much drama. But it sure didn't want to crank. And when it did, it ran worse with MORE smoke. "Hmm, I wonder if that was backward?" So I try 1/16 right (pump mark closer to drivers finder) and that seems to run better with less smoke. So is that right? Is the pump advanced by turning toward drivers fender? Or is something not adding up here?
Got to take the wife out tonight, so fooling with it will resume later tonight. Thanks for any help you can offer.
Side Note:
I noticed that (at least) one injector line is leaking slightly on the pump. But a quick careful check (no metric line wrenches) indicates it is fairly tight.
Just went back out there after letting it fully cool. Cycled the glow plugs, cranked it off without too much fuss, and it settled down fairly smooth with only (relatively) minor smoke. Let it idle a bit and warm up some. Hard to tell with the lighting, but smoked seemed to mostly clear up. Not sure if it needs more adjustment, or just maybe some time to run and come up to full operating temp.
Also noted that the intake track appears pretty oily. Does this indicate an issue, something that just needs cleaning, or something to be expected and ignored?
And finally, I read about doing a "diesel purge" to really clean up the system. Seems like it might be a good idea. Then again such things are often more snake oil than helpful, sometimes even damaging. Is this something that might help?
DmaxMaverick
09-18-2011, 00:17
The "Diesel purge" is hogwash. Forget it.
The crud in the intake is normal. If it bugs you, remove the intake and clean it. It's the accumulation of EGR gasses and CDR oil vapor. Non EGR engines will have a little less of the stuff. As bad as it looks, it doesn't really hurt anything.
You may need to adjust the timing more, but if it starts well and settles into a nice purr, it's close enough to get down the road. Advancing the timing to optimal will add a little power and economy. Ideally, there should be no smoke on startup, or during moderate throttle when up to temp. Heavy throttle should show a bit of black smoke, but not like a locomotive. You can time it with a timer, but I've never had it set according to spec. like I can do it by ear and feel. Too advanced will result in too much rattle and too high EGT (like a lean gasser). Get your leaks cleaned up before getting too adventurous.
Thanks much for all the advice!
Yeah, I hate leaks. So what's the fitting, and how best sealed? Just looking, maybe an AN type? Or is there an o-ring or something on the spider(?correct name?)? Also looks like the intake has to come off to access those fittings, so maybe a good time to clean.
Speaking of cleaning, I hate working on dirty engines, and while this is probably the cleanest non-cleaned 6.2 I've ever seen, I'll likely pressure wash it now that I know it runs (and can determine if pressure wash had a detrimental effect). Other than the obvious (air filter, oil filler, etc), anything to beware, cover, seal, or otherwise be concerned with pressure washing on the 6.2?
And another somewhat off the wall question. Since I'm now seriously on the track of building this for an econo daily driver, no concern for towing or hauling beyond maybe a TV or washing machine in the bed, what works out as the best gear for a light truck like this with the SM-465. It'll kill the off-line, but I'm thinking maybe one the the 2.73 or 3.08 axles would be just the ticket, maybe with some ~30" row rolling resistance truck tires. When combined with the low rpm grunt of the 6.2 and light body that should work well, and keep the motor in it's 2000-2400 peak range at 65-75 on the freeway (once it gets up there). If we need to do some real work, I've always got my chipped DMax/Alli to fall back on.
Oh, and at the risk of over stepping my welcome with too many questions (sorry, clueless 6.2 newbie), would the 6.2 "Volume 1" on this site be of use to me? I've got a factory service manual for 87 Light Duty Trucks, but are there better references for someone slightly OCD on this stuff and who wants to know all the ins and outs?
Not to worry
We have never banished anyone for asking questions, thats what this wonderful place is for, fo sure.
The fittings on the IP/lines are a special ball and seat sort of arrangement that is used on these things.
Now you can remove the intake and actually run the engine with it off, JUST BE SURE TO CLEAN THE AREA REALLY WELL AND KEEP AN LOOSE RAGS AND SUCH CLEAR OF THE INTAKE PORTS.
Wipe the leakers off and then loosen them slightly and retighten them a few times to "reseat" them.
Usually unless someone has really gotten rough with the fittings, this will get them sealed again..
A crow foot will help with some of the fittings to allow easier access.
Now once you get the engine warmed to operating temps and run it on the road to clear out all the unburned fuel and crap that is likely lurking in the exhaust, let the engine idle for a bit and observe the exhaust, it should be clear with no discernable smoke.
If you are still getting smokey wisps either the timing is still a tad slow or the injectors are bad.
Poor injectors will cause smokey idle.
Its an easy task to yank a couple injectors and get them tested. If the Pop and spray pattern are way out in the weeds you would be best to get them rebuilt.
Another check to make, is to jumper the Cold advance solenoid to see how it responds.
With the engine warm and the advance on the engines normal little chuckle should get far more rattly, if not it means that the Cold advance is not working right.
This can be due to a bad advance solenod or a worn out IP
The cold advance works by changing the case pressure in the IP which causes the advance piston to move to the advanced position.
Another thing to look for is the tag on the IP, Look to see if there is a colored tag attachd to the top cover bolts of the IP.
This tag may have a rebuilders date and such stamped on it.
I am suspect that there is a reason that the IP was retarded. This could be due to someone fooling around trying to solve an issue or ????
The best reliability, power and mileage with these little beasts will be achieved with a fresh IP and injectors.
Wrn out injectors and IP just makes any real progress a losing battle.
Sounds like you are getting on top of it though.
These trucks came with 3.42 gears as a popular ratio.
I have not had one with a stick shift, but the ones with the 700R4 mostly came with 3.42 gears and would get 24 MPG Hwy easily.
The little 6.2 will happily run down the highway all day long at 2100 RPM and give you some great MPG
Dropping the RPM way down tends to hurt more than help.
Keeping these little critters in the "Sweet Spot" is the goal.
1800-2100 at cruising. Dropping the RPM off into the 1500 range will kill the MPG's
Here is a link to a really good thread on Fuel economy http://www.thedieselpageforums.com/tdpforum/showthread.php?t=6954&highlight=RPM+mileage
Keep us posted
Missy
DmaxMaverick
09-18-2011, 09:39
There's really not enough info to determine why the timing was out of whack. Could be for any number of reasons. Often, folks mess with their engines acting on bad advice, or poorly applied good advice.
Depending on how many miles are on the engine and various maintenance items, it could have been due for a timing adjustment, and it was done incorrectly. As you found out, the timing adjustment is counterintuitive. The pump is driven by a gear on the cam, so the pump turns opposite the crank. To advance the timing, we turn the pump in the same direction as the crank rotation. Could be someone didn't realize this, and set it way out. This happens a LOT. At about 100-150K miles, the timing usually needs adjustment to compensate for timing chain wear. More than about 150K and the chain probably needs to be replaced, and the timing reset back to original.
As Robyn said, the fuel injector line couplings are a metal seat type. Usually, loosening and tightening will seal them. I suggest you don't do this, just yet. Get your timing ideal, then loosen all 8 of the lines at both ends (about 1 turn), then retorque them. This will relieve the stress on the lines from torquing the pump during timing adjustment, and help prevent line/seat cracking, and make line-injector alignment ideal.
The shop service manuals are great for most things, but will still leave you short on answers to the important/common questions. Having any of the TDP books on hand is a step in the right direction, especially during difficult problems. The service manual diagnostic steps will usually require tools you don't have or can't get, making it useless. The TDP troubleshooting and diagnostics were written for the DIY'er, in simple language.
Before I go very far into this, I wanted to make sure things were not going to go completely sideways. I've got the pump about 1/16" to the driver's side, and it helped a lot, though it still puts out gray smoke. I think it can go further, but the lines are really fighting and won't go further without some sort of persuasion. Is it ok to apply a modest bit of leverage? If so, where? If not, is it necessary to loosen the lines to go further, requiring the intake to come off. Or, is this as far as I should attempt to go with the advance? I saw some pics that showed pumps advanced at least 3 times the offset I've got now, but not sure if that's a good idea.
Also, with the need to advance this far just to get rid of gray smoke, seems that would likely indicate a badly worn timing set. Is this correct? The pump itself sure doesn't look too old, and has the orange tamper proof warranty markings, so I'm guessing at some point they put a new pump on without doing the timing set.
If I can't bring the timing a bit more advanced to eliminate the gray smoke, I doubt I'll be able to get it through emissions and tagged. So I've got to make more progress. Eventually it will likely get the injectors tested and probably replaced, but would rather not do it right now unless I'm sure that's an issue with getting it through emissions.
There is a pump turning tool, but I have not seen one in years.
Normally with the 3 nuts slightly loose, you can move the pump readily.
Lets check the timing chain slop.
With the engine warm and shut off, grab the crank pulley and see how far back and forth you can rock it easily.
The crank will usually move easily until the cam starts to turn.
If the slop is excessive (crank moves more than 1/2 inch or so at the pulley rim) then its time for a timing chain.
The timing sprockets in these last well and usually just a new chain will suffice.
The red/orange paint is a seal thats put on all the pumps when they are assembled at the factory.
Having to go through emissions is gonna mean that the tail pipe must show clean. The smokey trail is not gonna cut it for sure.
If I were you I would try to get a tad more on the advance, and then if the smoke continues, yank some injectors and have them checked.
Worn out injectors will cause lots of smoke that no real amount of advance is gonna fix.
Keep us posted
Missy
john8662
09-19-2011, 09:30
The Nuts on the injection pump lines are 5/8 (I know you mentioned above you thought they were metric).
Check the EGR stuff too. Ensure that the vacuum line isn't connected directly to vacuum, that it does go through the solenoid.
Just wondering myself if an open EGR valve would cause the smoke condition noted at idle. I know for sure it'll make one smoke like a tar kettle when WFO.
J
An open EGT can cause a very sour running engine due to the exhaust gas fouling up the combustion.
My guess is that the injectors are low on POP and slobbering a lot.
Missy
Well, didn't make much progress today. Work and family interfering again. :o Oh well, tomorrow is another day.
Thanks VERY much for all the help. From what I recall the EGR line goes to what appears to be a solenoid control on the driver's side, but I'll confirm tomorrow.
I did make a lever tool to help encourage it a bit more advanced. I stuck 2 tight fitting dowel pins (3/8" I think) in the spanner holes, and used a small pry bar between them to help fight what I assume is the line bind. It moves easily near the original line, but as you advance, it resists. Anyway, that worked well and it went where I wanted with little effort on the bar. It's now a bit less than 1/8" (maybe 0.100 to 0.110 or so) past the original timing mark. Not sure just how far I can safely push it, but the amount of smoke dropped again, and it still starts easily hot or cold. It is rather noisy, but then I'm probably spoiled by my DMax. I'm not familiar with the 6.2 normal sounds (been MANY years) so don't really have a point of reference for "normal". It now produces no visible smoke running down the road, and what I believe is acceptable and expected(?) for an NA IDI diesel when under load. I've got a friend with more experience on these things, and he thinks it will pass emissions now, so I may give it a try, probably Thursday.
In spite of it's mostly pristine condition, the odo reads 16k, so I'm assuming this truck has 116k miles. Combine that with the required advance and I think I need a timing set. I didn't get a chance to try the crank slop test tonight, I'll try that tomorrow.
I'll also get the injectors checked (immediately if I fail the first emissions test) soon. At the moment, I'm thinking my pump is fine, but we'll see.
I'll also be pulling the intake to try to stop the leakers soon. From what I'm reading, I may see about replacing my intake with an open "J" intake, depending on how thorough emissions inspection is when I go.
I hope I didn't forget anything. Thanks again!
Good to hear.
The Rattle on these engines is far and away more (Normally) than a Dmax
The 6.2/6.5 gets all the fuel for any given throttle setting in one shot, where the Dmax has a controlled injection that spreads the injection out in several little squirts.
The "pilot" injection allows the engine to run very quiet.
If you get an electronic injected 6.5 and the timing is set to the top end of the spec and the injector pop pressures are right up to the line too, they will rattle real good, maybe even make a powerstroke blush a bit, especially when cold.
Missy
Well, I suppose it's over due for an update. Sorry to disappear, the week got hectic (and then some).
I guess I didn't do too bad. I finally got a chance to take it to emissions today. It blew 2.3 out of allowed 20% on the opacity test. And it still cranks easily enough cold or hot. So I guess that's not too shabby. When it cools off a bit more (still 108 today), and I get some free time, I'll pull the injectors and have them tested, but with that good on emissions, it's not too high on my priority list. The final timing was about 0.110 advanced from being aligned (no idea how many degrees that represents), so it's a safe bet the timing chain is stretched, so it'll likely get a new Cloyes timing set this fall too.
Next up, finding an OD manual trans I can afford (probably a long wait) and 2.73 geared axle. Right now the sweet spot feels like it's right about 50 mph. 65 on the freeway it's starting to scream like a banshee. The latter is by far the most practical cost and work wise, so far more likely for short term.
But the best past that now, after at least 3 years setting, its a driver!
Now that I'm over the emissions concerns, I'm on to next steps, and have a few more questions.
1) Should I be concerned with the almost 1/8" advanced of the pump? I read about folks damaging their motors when they go "too far", but is mine too far? According to the test, I was way to concerned about reducing smoke, so maybe I should go back a bit? Also, the goal of this truck is mileage, so will extra advance hurt or help mileage?
2) I'm pretty sure I'll have to pull the intake to stop my leakers. With monkeying about on the timing, I now have several leaking, enough to drip off the back of the motor. A friend has a J code intake, is it really worth swapping? The emissions guys didn't open the filter to look for EGR, but they did verbally note that it was a "light duty emissions" (as shown on their screen), and everything looked good. So it might bite me if I were to remove any of the visible components. I'm not looking for maximum power, but (nearly) "free power" without costing (much) mileage is always good. So, is the J intake likely to be worth swapping on while I've got the intake off?
DmaxMaverick
09-24-2011, 11:28
Now that I'm over the emissions concerns, I'm on to next steps, and have a few more questions.
1) Should I be concerned with the almost 1/8" advanced of the pump? I read about folks damaging their motors when they go "too far", but is mine too far? According to the test, I was way to concerned about reducing smoke, so maybe I should go back a bit? Also, the goal of this truck is mileage, so will extra advance hurt or help mileage?
If it doesn't sound like marbles in a washing machine at idle or acceleration, it isn't too far. A high mileage engine can be even further. This is a good indicator of a worn timing set and/or tired injectors. A new chain or gear set and fresh injectors will set things back right. Advancing will only help mileage. You'll get noticeably too far long before the mileage decreases. It helps if you have a pyrometer to actually "see" how far is too far. More advance is better than smoke.
2) I'm pretty sure I'll have to pull the intake to stop my leakers. With monkeying about on the timing, I now have several leaking, enough to drip off the back of the motor. A friend has a J code intake, is it really worth swapping? The emissions guys didn't open the filter to look for EGR, but they did verbally note that it was a "light duty emissions" (as shown on their screen), and everything looked good. So it might bite me if I were to remove any of the visible components. I'm not looking for maximum power, but (nearly) "free power" without costing (much) mileage is always good. So, is the J intake likely to be worth swapping on while I've got the intake off?
The J code intake is worth it if emissions isn't a problem. The next guy may pop to top. You can plug the EGR vacuum line and leave it in place (plugging the hole in the air cleaner housing). At least it'll "look" like it's doing something. Keep your original intake for the inspections, if it becomes necessary. This recommendation is for "off highway use only".
Thanks again!
It now has a full idiot light cluster, but will eventually have all basic gages and possibly/probably a pyro. Just not there yet. But no where near "marbles in a washing machine", so I'll leave the timing where it is.
Seems like swapping intakes on these isn't too terrible (easier than SBC), so I may take the gamble to swap and leave the visible portions intact for visual inspection. In this respect, too bad it wasn't a 3/4 ton, but that would make the axle gearing goals more problematic.
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