Tore down my 6.9 to the short block. Going to install head studs, because i will be running a banks sidewinder on it. And look what i found! Oh Lord, what happened. All the pistons look like this, except one looks brand new. One actually looked like it had dirt burned to it? Cylinder walls look like mirrows, no galling or nothing. Heads look ok too, with the exception of one small divet. But nothing like the pistons. Will these be safe to run with a turbo. Or should i just go ahead and do a complete rebuild? This motor is a pretty fresh motorcraft reman. It came out of my 86. It ran great, never gave me no problems, no strange noises or anything. 86 is donating the motor to my 89 with the turbo. Pistons are marked .040 on the one you can still read, so i assume they were installed when remanufactured. I actually bought the 86 just because it had a fresh powerplant in it, for my 89. But now i got a snag. Any help, advise, ideas would be greatly appreciated. Thanks.

 

Looks like the tips of your glow plugs broke off and played around in there to me.

 

Glow tips popped - no doubt.

I wouldn't run it as is.

 

Must have happened to previous owner. Glow plugs look like new? How come it didn't scare up the cylinder walls? Or beat the heck out of the heads? And how in the heck does a glow plug fail like that? Can it be prevented? And were is a good place to buy pistons? Should i go with hyperuretic? or just cast?

 

Since you are tearing it all down, and turboing, I'd go with some heat resistant anodized ones at least. That looks nasty and I can't believe it was running. Never heard of all of them but one being in that bad of shape.

 

Yea, the old 86 made a many a trip to the deerlease and back, to work, around town. Never even coughed! Ran like a top! Cant believe it did with pistons like that either. Were can i get those anodized pistons your talking about? Dave said something about hyperuretics in another thread some where. not tryin to build a hot rod, but want it to be good and strong and last a long time. Thanks for yalls inputs! keep em comin.

 

Couple of possibilities....you said it was rebuilt....whoever rebuilt it before either saved some .040 over pistons, waiting for the next engine who needed a bore that big, and unfortunately, you got 'em....or, they were the original pistons with that engine, whoever rebuilt it just seen the heads were thrashed and replaced them. Most of the time, your heads and pistons take the brunt of loose objects in the cylinder, and leave the bore alone.
If you have the money, get some different .040 over pistons and rings, hone the cylinder bores, and put them in. If not, I guess since it was running, I would re-assemble without a turbo and keep running it until it dies a natural death. Might last for a few thousand miles, or it might last forever.

 

I think the pistons are roughly 0.375" thick at their thinnest point in the center of the crown and bottom of the prechamber. In theory, the pistons can take a helluva beating and still keep on going as long as there aren't any cracks in it, however you are still taking a chance.

If there are no marks at all on the head, then it could mean the pistons were reused after a glow plug "incident". The hyperutectic aluminum alloy in the piston is softer than the cast iron head, but usually there are still some marks left there if you look close enough. Unfortunately, it costs money to do a proper rebuild and most guys don't bother to put much effort into rebuilding an IDI. When I see an ad for an IDI powered truck that claims it was "rebuilt" I shudder.

 

I have two in my motor but they are NOWHERE near that bad the just have a few nicks about .005" deep.

 

Man that's horrible!

 

Hey Guys...off topic here, but what is that pipe looking thing on the side of that block that has the red rag on it?

Pete

 

That's the oil cooler.

 

No wonder I didn't know what that was. My 6.9 doesn't have one. That explains the oil filter mount move hooked up to an aftermarket oil cooler on mine...


Thanks,

Pete

 

Is your aftermarket oil cooler water cooled or air cooled?

 

From the looks of it I believe it is air cooled. The lines go to a big cooling fin in front of the radiator....almost as big as radiator but thinner...it's not the A/C fins...that's behind or right in front of radiator.

Pete