Wrist Pin = New Block????

[EscaladeDiesel]

Continuing from my "Rapping" noise problem....My mechanic says the heads and valve train are good. He believes a "wrist pin" is bad. He is going to go into the engine tomorrow. He says that most likely, I will need at the very least, a new short block. My question is to everyone is: Once the initial "rapping" noise occurred I only drove the vehicle 10 miles to get it home. It's been started a few times to do diagnostics. It wasn't until it was at the mechanic that it started to make the louder and more consistent "rapping" noise. Is it more than likely that the broken wrist pin (if found to be broken) has caused enough damage to ruin the block under these circumstances? Odd the turbo and lifters survived the loss of oil but the wrist pin didn't? :confused:

[ 02-18-2004, 09:04 AM: Message edited by: EscaladeDiesel ]

[Jim P]

If your engine has a rap and was run without oil, I would bet that it is a bad rod bearing. The wrist pin bushing could go way longer without oil than the rod bearing because the bushing only moves back and forth a little bit with each revolution of the engine. The rod bearing turns all the way around.

I the wrist pin did break(which I doubt), the only real damage it would cause would be to the piston and rod unless the piston came competely disconnected from the rod. And if it did, you would know it. It would be more than a little rap.

[ 02-18-2004, 12:47 PM: Message edited by: Jim P ]

[EscaladeDiesel]

Thanks for the info Jim I appreciate your input, it was sorta what I was thinking, found it hard to believe that since the engine runs well, except for the rapping that the block was ruined. I am going to pass along your knowledge.

[Kennedy]

The wrist pin is splash lubed and do not require large amounts of oil (although it wouldn't hurt) to operate. The bushings will typically be black and blue, but if the problem is up top, I'd lean more towards a piston issue. The pin will not break, but a clip could let it walk out to the wall...

[EscaladeDiesel]

Hi John, if the clip did let the piston walk out to the wall is the block ruined and not repairable?

[grape]

Why didn't this guy pull the pan off before he did anything else considering there was a catastrophic oil loss? Since it blew all the oil out of it, I would be more inclined to look at the bearings than anything in the top of the engine. I hate to sound mean but i think this guy is looking everywhere but where the problem is to get as much money out of you as possible by diagnosing everything but the root of the problem before he says....."umm you need a new motor".

[EscaladeDiesel]

Yes, I am concerned to say the least, hence my asking for advice here. He seems to be an honest and genuine guy, but it appears the first problem is that he is putting all his "fleet" diesel work before doing thorough and quick diagnosis on my Suburban. Unfortunately here in Denton, TX he is the only diesel mechanic I could find. I had dealt with the dealer here, and they were completely incompetent.

[diesel1995]

I had a drag car at one point that had full floating wrist pins that were snap-ringed into the pistons, and floated on the rods.

Good for less friction, and ease of installing pistons, but i had a clip come loose one time.

Without further intro, i would agree with John, it is more likely to be a piston or rod issue than a wrist-pin issue.

That said, if the clip was to come off and let the pin walk in the cylinder, not only could it possibly ruin the block by putting a groove in the cylinder wall (could be fixed with a sleeve), it would ruin it for sure over a long period of time.

[EscaladeDiesel]

My mechanic didn't think the 6.5 could be sleeved because there wasn't enough tolerance / clearance. If that can be done, does the engine have to be removed from my suburban?

[Quack_Addict]

#1 if the engine was run low on oil, the problem is almost certainly in the rotating assembly. If this is the case... new crank and rod/main bearings. The one 6.2L I ever had that was run low on oil spat pieces of bearings out like teeth. To remove the engine, I had to take off the oil pan and loosen all the bearing caps to get at all the torque converter bolts. There was not very much piston / cylinder damage; I guess the lubricity of the fuel helped save that aspect of the engine.

#2 I don't see why a Diesel engine couldn't be sleeved if a wrist pin did let loose in some manner. All a sleeving operation involves is boring the cylinder over stock dimension and tapping the sleeve back into the bore to bring the diameter back to or near stock dimension. I've never heard of it being done on a 6.2 or 6.5, but it is STANDARD practice on pretty much any gasser.

[ueckebes]

escalade diesel , howdy fellow texan cant tell what might be wrong with your 6.5 after being oil starved but i would guess rod bearing not wrist pin . anyway your mech may be a good guy just not very familiar with gm diesels . these engines can and are frequently bored ,and sleeved.if youre having trouble finding a decent diesel mech go to a local truck stop or even many convient stores and get yourself a truck trader magazine , they usually have several listings [ads] for shops and salvage yards in them. anyway let us know what you find ,good luck jim