Now how did I do this? Cracked Pistons.

[wayne pick]

Andrew, I found it by searching- GM 6.2L diesel .75 oversize pistons. Location is Westminster CO. Posted as a complete set of slightly used Federal mogul .75 over 6.2L pistons. Post dated 2012-01-28. Check out lower left side photo u will see a slight blemish on top of the piston where it looks to have smacked something. They don't look that great to me, burning on the skirts on two of them- blow by? If u can't find this, e mail me and i'll send it to u. WCP.

 

[AndrewH]

I was able to locate pistons new from a guy in southern MI. Middle of next week I should see them....... Thanks Wayne, I'll take a look.

 

[wayne pick]

Exelent, new is the way to go, and local. No killer shipping charges. Post updates-pics on your repair. Good luck. WCP.

 

[rickf]

Andrew, I found it by searching- GM 6.2L diesel .75 oversize pistons. Location is Westminster CO. Posted as a complete set of slightly used Federal mogul .75 over 6.2L pistons. Post dated 2012-01-28. Check out lower left side photo u will see a slight blemish on top of the piston where it looks to have smacked something. They don't look that great to me, burning on the skirts on two of them- blow by? If u can't find this, e mail me and i'll send it to u. WCP.

That would have to be a typo, .75 is 3/4 of an inch! That is one BIG overbore! Standard overbores are .020, .030, .060. Make sure of what you have in there before ordering, some engines came from the factory with oversize pistons or bearings. It was perfectly acceptable.

Rick

 

[Ken_86gt]

No typo- he mentioned earlier .75 mm, not inches.

 

[rickf]

Sorry Ken, I just went back through all of the posts and I don't see that. Never see American engine parts listed in mm. At least not in my 40 years as a mechanic. Working with foreign engines I dealt with it all the time. No matter, just make sure what is in the engine is the same as what is being ordered.

Rick

 

[epartsman]

I've had to do it sometimes with CUCVs and HMMWVs I've just *had* to get running for emergency reasons, but always, always, always disable the glow plug systems first, and when you hit the spray button on the can it's *barely* a half second. On a CUCV you can pull the card under the dashboard.

I was wondering if the damage was ether start too. Put too much ether in and it detonates halfway up the compression stroke and breaks stuff (con rods, pistons...ow ow ow.)

A sticker on my air cleaner states under no circumstances use either to start this vehicle.

 

[Wile E. Coyote]

A sticker on my air cleaner states under no circumstances use either to start this vehicle.

Right. But it says that because in the factory state of the vehicle the glow plug system is operating when you try to cold start the vehicle, and when the ether comes into contact with the hot ends of your glow plugs it detonates and swells them. I've pulled many, many, many swollen glow plugs out of CUCVs and HMMWVs because people didn't disable the glow plug system before attempting an ether start, and I would like to round up all those people and drag them through town behind a stagecoach. Alot.

 

[wayne pick]

rickf, That .75mm/0.30 was in the craigslist posting, I neglected to put mm after the .75 in my reply. I don't have a conversion table in front of me so I assumed that is what it works out to. Thanks for making a point of pointing that out.

 

[AndrewH]

As far as being an "American" engine, there are a lot of metric fasteners on the 6.2s. The oversized pistons are stamped ".5" on them. I have another set which are stamped "1.000M".

 

[rickf]

As far as being an "American" engine, there are a lot of metric fasteners on the 6.2s. The oversized pistons are stamped ".5" on them. I have another set which are stamped "1.000M".

HMMMM, I will have to look at my parts pile. I have a complete engine in parts minus the block, crank, timing cover. Customer told me he had his wife crank it while he shot "Just a little" ether into it. BANG! Broke the crank right behind #2 rod like usual and broke the front main saddle and turned the timing cover into scrap metal. Bent # one and two rods. Probably cost both of them a pair of underwear!

 

[Tanner]

Check your IP & have it set to factory specs. Turning up the IP on a weakened/wounded engine just exacerbates the problems & helps find the weak link in the chain faster...

 

[AndrewH]

Pistons are on their way here, pump is correctly timed per the -34, pieces and parts cleaned. new gaskets here......

I have found that .5mm over, .75 mm over 1.. over roughly equal 20, 30, 40 thousanths over. Maby it just depends on the mfg of the piston.

 

[wayne pick]

Yea Andrew, Funny u say that, I looked up the conversion and found .75mm = 0.0295275591 IN. close enough for me. .77mm= 0.303149606 in. may be a bit too tight. Are u gonna put a crank girdle on it? No proof they work, but it can't hurt. Don't forget the pic's when u start building. Later, WCP

 

[AndrewH]

No girdle for this one. Thats for the turbo motor..... Pics yes.

 

[AndrewH]

Ok people, I know you have been waiting for an update. I hope th popcorn has held out. I have the engine back together and have been driving it to woek for the last week. All is well. No blowby, no bad smoke. no weird noises. All cylinders have right around 415 psi compression. Having the pump timed to its correct setting make starting take a little longer but no big deal. Mileage has gone up a 3 mpg as well. Looks like we are good for now. I'll get some pics up. My assistant might have maby gotten oil and diesel and carb cleaner in my camera so the pics are foggy. Who makes an oil resistant phone?

 

[wayne pick]

Exelent! Good to see someone actually repair a 6.2 and not just give up and swing another motor in.