It's not broken! I'm baffled, uncle!

[john8662]

Well, I pulled the engine from my '95 K2500 Burb that left me stranded in MT to see what's the matter, why the Harmonic Balancer and crank pulley attached to the Balancer would wabble badly when the engine was running and would intermittanly have the engine making a nasty vibration.

I figured, drop in oil pressure, plus when rotating the engine by hand it had play, that it might have suffered a broken crank.

I dunno.

Well, the slop was likely just the gear drive timing set with play before engaging the valve train, not used to that feel I guess of rocking the engine.

I've got the engine down to nearly a bare block currently, what I'm seeing inside doesn't make me happy anyways.

The crank isn't broken that I can see, although it's still in the block, but with all the main caps removed.

So, why the wabble and the wear on the gear drive timing set crank gear?

Theory, the crank snout has been bent all this time and I never actually WATCHED the thing run, never thought to look, ya know? So, when it started running weird, it coulda been something else at work, and when I saw the balancer, I just jumped to conclusion that something had failed. My fair conclusion considering I had been dogging the heck out of the engine the whole trip.

During the engine build, this crankshaft arrived to me via UPS and when it did the snout of the crank was hanging out of the box. I had my machine shop look it over, but they just polished the journals, cause they didn't like the finish, and said good to go. I was suspicious, but didn't know how or where to have it checked, and it was already balanced to the rest of my rotating assembly.

One thing I tried last night. Took my magnetic dial indicator and rigged it to sit on the front of the block with the dial reading AROUND the diameter of the crank snout, w/o balancer. I zero'ed the dial and rotated the crank to just before and just after the Keyway. I did find .0015 of variance in this area. I dunno if this is it or what...

The bad, seeing not-so-good bearing wear, with 5k on the engine, it shouldn't have a lot of the babbit layer off the bearings. The rod bearings look the worse, but they all don't look good at all. Down to the first Aluminum layer on some uppers. But, this could also be attributed to the small coolant leak on the bottom end on one of the splayed holes. Sealant was on them all, but what sealant actually does what it says it'll do (another beef I have). Something that surfaced during the trip.

Somethings not quite right here.

For the time being tho, I think it's safe to say that this project is just about dead. Got some decisions to make, build another 6.5 or stick with my interest and convert on over to a Duramax. The "Cat" 6.5 that I'm working on could make a future racing platform, but not a reliable engine for my vehicle I dearly miss as a daily driver. At least it ran good for a little while, the 4WD burn-out was kind of interesting.

In the mean time I've got some more investigating to do. This engine will NOT be re-installed in this Suburban. I found a race shop in town that can do splaying and the like. I want to take the block down and have them fully check the align bore in the block, engine never did rotate like it should.

Well, that's it...

This engine has been a complete pain in the butt, it never started good, always had some little issue. I swear it's cursed!!!

:confused:

[Kennedy]

You've made it this far, I'd resign myself to finding the culprit.


I'd suggest taking your parts to a knowledgeable shop and:

Check your align bore on the mains.

Check the crank for true. More than just the front and rear main to snout, all mains as well.


Also check the cam bearings as they can affect the oiling to the bottom end.

I might also suggest just using a new crank from AMG.


Greg at Lube Specialist also had lower end bearing problems with a reman engine done in the South. I don't think he ever found the issue, just replaced the whole deal. Not sure how much of Yours was carried over from the original build.


P.S. Maybe have this shop assemble the recip assy for you. I know it's not that tough, but these kind of guys typically really know their stuff. The crank should spin in the mains like butter using motor oil or motor oil/STP as an assy lube. I think I've seen guys simply use WD-40 in the cylinders, but don't hold me to that.

[john8662]

Thanks JK,

You've given some solid advice on a pretty grim situation.

Thank you!

I will find out what the cause is. I just know it won't be simple at any rate.

A new crank is a definite possibility, probably a scat.

[More Power]

P.S. Maybe have this shop assemble the recip assy for you. I know it's not that tough, but these kind of guys typically really know their stuff.

This is why TDP hasn't produced extensive engine rebuild information. There are a couple here who could do this, but the equipment and expertise required takes this out of the realm of the typical 6.5 owner. I had the engine shop build the shortblocks for the past two engines I've had done. I installed the cyl heads, timing covers and tin.

I'm glad it wasn't a broken crank....

Jim

[Kennedy]

When I had mine done I recalled discussing a hidden plug (just like the small block) with my builders. This plug absolutely needs to be removed during the cleaning process. I believe that they drilled and tapped it to pipe plug it. This plug diverts all oil out to the filter and cooler. If not in place, oil will miss the cooler and filter (there may still be some flow) and go direct into the engine unfiltered.

Also, coolant in the oil will tear up the bearings VERY fast. For this very reason, I highly recommend using straight water on initial break in when weather permits. I had this issue with my head studs and ended up using GM seal tabs.

[Kennedy]

Thanks JK,

You've given some solid advice on a pretty grim situation.

Thank you!

I will find out what the cause is. I just know it won't be simple at any rate.

A new crank is a definite possibility, probably a scat.


Probably China build. most Scat stuff is not very impressive...

[Robyn]

John

I have built 5 of these engines from bare blocks up in the last few years.
The last one was my own (94 Burb)

This is just not an issue that should be that tough to rectify.

It would ne great if you can find someone in your area with a mandrel that will lay in the main saddles to allow you to check the main line.

But as has been mentioned if things are good the crank should rotate smooth as a babies butt with oil or any good lube in the mains.

I would do this. Start with just the two end mains bolted just snug and the rest off the block.
Indicate the center main journal and see what you get for runout.
Should be very minimal as in less than .001".

The other thing Im thinking about is the converter.
If this rig has had a converter replaced I am suspect.

Yank the converter off and "Gently" grab the pump pilot hub in the lathe.
(GOOD acurate chuck needed) and indicate the crank pilot nub on the front of the converter.
If the pilot is wabbling around like a button on an outhouse door you have an issue.

I have seen two 6.5's with 4L80's that had rebuilt converters that were absolute crap.

The last one I saw that was bad was off .130" Yes thats right over 1/8th inch.
The engine shook like a box of pudding.

This can tear one of these little engine to pieces in short order.

When everything is tight and new it might now show so much but after a hard run up to Mt from Tx it would have had plenty of time to rattle stuff loose.

The bearings should not show any wear hardly at all in 5K miles.

With the crank out have a look at the oil feed from the cam to the mains . The cam bearings can have the oil holes almost anywhere as there is a groove behind the cam bearings to direct the oil from the galleries down to the mains.

Now yours is a spray block, did you use the high volume late model oil pump???

An early pump will work but after a good hard run and things wear a little an early pump will not provide the needed volume to lube this engine with all the loss through the spray holes.

What was the oil pressure at running and idle while you were running it up yonder???


This whole thing does not make sense at all.
Also take the crank out and stand it up and go along and smack it at various places along its length. You may still have crank issues but it may be just cracked and not totally broken yet as you noticed issues and shut it off.

That crank should have a nice sweet ring to it all along its length.
You certainly could have an issue there thats not visible just yet.

So many folks just drive the poor little creature until the scenery stops going by or pieces fall out on the road.

Later let us know

Robyn

[john8662]

Well, block went to the machine shop to see if they could shed some light on the bottom end situation.

I wanted to verify the align bore on the bottom.

Well, I get a call this morning (they jumped right on it, dropped off mon @ noon.) that the bore was too tight and they ran the mandrel down the center to correct with the caps bolted down to the torque specifications I provided them with. They already had case size diameter specs on hand. I would figure that since the case/bore size was too tight that perhaps that would have shown up on the build in the form of bearing clearance, which was checked.

So, this can start to explain some of the oiling issue, mystery still not solved, but moving in the right direction.

The other oil issue is likely the camshaft journal size being on the low side of the scale, it will not be re-used this time.

Robyn,

The Block is a 1994 '599 block, no piston oil spray cooling. The HO oil pump was still used on this engine for it's improved volume, to help with the rather large oil cooler up front.

New parts will be acquired as funds allow.

New Crankshaft
New Fluiddampnr in place of Factory HB.
New Camshaft & Lifters.
New Bearings, that will NOT be Clevite 77.

[Robyn]

Hmm I am wondering about your choice not to use clevite77 ???
Always tops on my list of parts to use.

Do check that converter though if it was replaced.
If its not the stock unit it must be considered suspect.

I am still currious, how much loos of oil pressure did you have when things got hinky up North???

I have never seen a cam that was worn that far to cause oiling issues.

Any chance that there is a leak in the front gallery plug/plugs???

Turbo issue such as too much oil going past the bearing??
Cooler bypass failure??

Just some thoughts

Good luck

Robyn

[Kennedy]

Did they check the hidden plug?

I'd also ask the machine shop about the Fluidamper. Not many engine shops have much use for them...

[john8662]

Robyn,

The converter in the rig is original, so I had not suspected it.

The oil pressure loss wasn't dangerious, but all of a sudden less than what it had been running.

The engine had been running a constant 55-60 psi at 2400 RPM down the highway, basically anything above 2k RPM it ran this pressure, always has. When I noticed a difference it was running 40 psi at the above mentioned RPM's, and the standard 25 psi at idle, which didn't change. It continued this lower pressure even cooled back down, and till the day I yanked it's butt out of the chassis. I started and drove it from the street up into the driveway (no more shop) when it got yanked.

Turbo? Not that likely, I'll know soon enough as I'm in the middle of swapping the turbo off my shorty truck for the one that was on the Burb.

You'll also have to realize, I'm a gauge freak, I keep a keen eye on them all. My independent aftermarket gauges also consist of boost (30psi), Pyro, Trans Oil Temp, Dig. Fuel Pressure, Dig AIR Temp, Dig Coolant #8 temp. Yep, 6 extra gauges.

So, when things change, I'm usually aware.

I also realize that many 6.2's and 6.5's don't usually display the pressures mentioned normally. All of mine do, except the '97 piston oil spray block in the '82 pickup. Norm to me, even the ol '83 Gvan 6.2 in the family does the same with 200k on the clock.

Maybe it's the altitude :rolleyes: ?

[john8662]

Did they check the hidden plug?

I'd also ask the machine shop about the Fluidamper. Not many engine shops have much use for them...

I'll ask and see when I go pick it up.

The plug in question was removed and re-installed when this engine was being prepped for assembly the first time. It was removed for vatting.

I never saw it personally, but it's a soft plug I'm thinking.

[More Power]

What was the cause of the wobbling damper?

If you use a Fluidampr, and if you balance the rotating assy, you'll need to balance the assy using the OE damper.


I'd also ask the machine shop about the Fluidamper. Not many engine shops have much use for them...

JK, what reasons do the engine shops cite?

Jim

[john8662]

What was the cause of the wobbling damper?

If you use a Fluidampr, and if you balance the rotating assy, you'll need to balance the assy using the OE damper.



JK, what reasons do the engine shops cite?

Jim

Not known what the culprit of the wabble is yet. That is the question that is still burning on my mind as well. Two suspects: Crank or defective (albeit new) dampner (Gm, not China).

This is primarily why I'm currently opting to just replace them both.

I'm thinking of having the crank balanced for my rotating mass at Scat, have to see whether that can be arranged at a later date or not, but with stock balancer. I hope to not have to buy another stock balancer tho.

I talked to the machine shop doing the case sizing about several things, the owner was there, kinda funny/obnoxious type but very knowledgable.

Anyways, he says (for some monetary funds of course) that he thinks he can check the crank's snout area for true. I offered to bring both the balancer and the crank to him. Whether I can do this or not is in the air.

I also asked about Fluiddampnr, as suggested by JK.

The guy didn't like them. But, this is solely based on Gasser race engines only. This was because of two main reasons:

1). The pure heavy mass/weight of the new balancer, too much for many engines, says that some of the engines he's done work with have actually suffered broken crankshaft snouts solely due to the weight (his story).

2). The cold temperature story... That he feels that the engine would be out of balance during colder temperatures before the fluid viscus could move properly. He then showed me a taken apart balancer, to show me the free floating ring inside. He said that the ring wouldn't be able to properly reach center if the fluid was too cold.

He did offer to say that perhaps being that what we're playing with turns "such low RPM's" that it would be our saving grace...

Then said, "make yer own mind up."

On a positive note about products, said he liked the scat cast cranks well, then listed off things to look out for in an aftermarket crank during assembly in the fit and finish.

Where were these guys a couple of years ago!!!

J

[Fluidampr]

John,

Just to add some info on the Fluidampr to clear up some of the myths / rumors we see every day over the past 20+ years. Reason #2 that your engine builder claims is false. The reason we use the specific silicone fluid we do is because of its ability to not change with temperature. It's very impressive to see how this fluid does not change characteristics from extremely cold temperatures to higher temperatures you would only reach if your engine was on fire. It goes back to when we built some dampers for aircrafts, we all know the extreme temps they see during flight.

Reason #1 has been claimed by many people however we have never seen any direct physical evidence that leads to crankshaft failure due to the Fluidampr. I have also known people to claim that their rubber damper broke their crank. All I do know for sure is that we have test data that proves our Fluidampr reduces torsional vibration compared to the stock rubber damper, especially on diesel engines. The fact that our Fluidampr is sometimes heavier than stock dampers is because we need a certain amount of inertia to out perform the stock damper. More inertia usually means more weight.

I have seen many times that the reason a stock damper is wobbling while the engine is running is usually due to the rubber ring being worn out. Let's face it these older 6.2L / 6.5L engines don't usually have their dampers replaced when needed. Just like an old tire the rubber can dry rot & crack, once that happens the outer ring is free to start moving around which will eventually lead to the outer ring to fly apart causing more damage. Which I do have experience with. For more info with pics & test results you can go to our website at www.fluidampr.com.

If anyone has any questions please let me know.
Thanks,
Dan

[Kennedy]

Reason #3: There is no way to test the actual balance, the unit, or know if the product is functioning properly.

[john8662]

Dan,

Thanks for the additional information concerning the information/opinions I was given.

I had pretty much made my mind up before asking anyways, that I wanted to use one.

In the case of the wabble I was seeing, it wasn't just the balancer that was observed wabbling, it was both the balancer and the crank pulley, which bolts to the center of the balancer that is not isolated by rubber. Not likely to be just the outer damper ring.

J

[More Power]

Here's the new article on the FD! :)

http://www.thedieselpage.com/features/fluidampr.htm

Jim

[twaddle]

JK,
Fluid dampers can be checked to ensure that they are working as they should.
It requires a special piece of equipment, looks like an electronic set of scales. The damper unit is sat face down on the tester, a switch is pressed which activates the tester which puts a vibration at a set frequency into the damper, the test unit then tells you if the damper is operating by the way the damper has controlled the vibration.

We used to have fluid dampers tested this way when rebuilding engines fitted with fluid dampers to ensure we didn't get any comebacks (broken crankshafts) due to faulty dampers.
The only dampers that tested faulty generally had external damage (dings and dents) which usually restricted the free movement of the internal damper ring.

Jim

[Fluidampr]

Dan,

Thanks for the additional information concerning the information/opinions I was given.

I had pretty much made my mind up before asking anyways, that I wanted to use one.

In the case of the wabble I was seeing, it wasn't just the balancer that was observed wabbling, it was both the balancer and the crank pulley, which bolts to the center of the balancer that is not isolated by rubber. Not likely to be just the outer damper ring.

J

John,

The crank pulley does also act as a damper since there is a rubber ring in that as well. So if the rubber is worn out in the pulley you will also see it wobbling.

Let me know if you have any other questions.
Thanks,
Dan