My options, and your opinions.

FrozenMerc said:

My $0.02, and it probably isn't worth that.

Build the engine you want now, build it right the first time, and be done with it. I understand the funds may not be there, or other complications may arise. However, find a way to make it happen. The older I get, the more of a rip the band-aid off now type of person I have become. You just don't know what monkey wrenches are going to be thrown into your best laid plans next week, month, year. Plus, unless the Fed throws us into a deflationary spiral, ala Japan in the 90's, it will only cost more and more to build the motor you want now, later on down the line.

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I'd love to Merc, one day I will. And you and me will sport the prettiest trucks in the world. But right now I need crank up, run, go, and stop.

Tear apart the cavitated 7.3 and see what you actually have. If the rotating assembly in that is actually good, then swap it into your IDIT block. Check that block deck for flatness, choose the best 2 heads out of the 4 7.3 heads you have, and put it together. You'd then have a running 7.3 for no more then a set of rings/bearings/gaskets.

Finding 2 .030 pistons for a 6.9 isn't impossible, but I wouldn't count on doing that if I was in a time crunch. Put that motor under the work bench and keep an eye out for what you need. You might stumble upon it someday and then have a good motor, but like I said, sourcing those pistons is something I wouldn't count on doing if I was in a time crunch.

I'm like the others in that I prefer to do things right the first time. But if this needs to be running, you really don't have the time for that, so do the best you can with what you have. Get one of them running first, then you can spend the time doing a build.

Is this it but a little cheaper?

franklin2 said:

Is this it but a little cheaper?

International .030 Piston Asb | 141651

.030 Piston Asb (7/64 Oil Ring) (1)(2) International 6.9L V-8 Diesel Engines

www.jensales.com

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If the top of the piston looks like that, I don't think it's correct. Someone else will chime in and we'll get a concensus.

Austin86250 said:

Can you just bore a 6.9 into a 7.3 or is there complications in that process?

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Head bolts are the issue there.

What type of head gaskets are on factory engines?

Jesus Freak said:

If the top of the piston looks like that, I don't think it's correct.

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No. IDI pistons don't look like that on the tops. Those look like a 7.3 PSD piston.

IDIBRONCO said:

No. IDI pistons don't look like that on the tops. Those look like a 7.3 PSD piston.

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They look like tractor pistons to me. But maybe that's the generic piston picture, I might call them.

Since the picture is labeled "Farmall and International", that could be. It also may be that this company has no idea what it's trying to sell since I didn't see a disclaimer about it being only a stock photo.

Maybe I'm not thinking about this correctly. But - Assess why the pistons melted?

Swap over the other 7.3 pistons from the cavitated engine, turn down the fuel and be done with it? Did EGT show an issue? I only covet my neighbors IDIT, and only have experience with my 6.9.

PossumTruck said:

But - Assess why the pistons melted?

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Depending on how they look, it's probably perfectly normal. I've seen it a lot on engines with turbos on them. They pistons will start to burn/melt around the outside of the tops. My guess, and Wes from Classic Diesel Designs agrees, is that it's from running too high of EGTs and no pyrometer. I think that it's from people who think "I have a turbo, I can pull the world" and keep their right foot close to, if not on, the floor and don't let up until they have to.

IDIBRONCO said:

Depending on how they look, it's probably perfectly normal. I've seen it a lot on engines with turbos on them. They pistons will start to burn/melt around the outside of the tops. My guess, and Wes from Classic Diesel Designs agrees, is that it's from running too high of EGTs and no pyrometer. I think that it's from people who think "I have a turbo, I can pull the world" and keep their right foot close to, if not on, the floor and don't let up until they have to.

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No EGT gauge. I don't lay on it like a nut, once a month when I pull my hay trailer I do have a couple big hills I have to confront (nothing like @Cant Write and ole dog pass, valley of the shadow mountain, and can't climb this mountain hill that he drives on) pulling a hay trailer, and since I run waste oil I use it as a chance to "burn out" the combustion chamber but I don't get nuts with it. Other than that it's just my daily driver. My guess is that there was a deal of wear previously and the fuel turned up and a turbo and it was my time to "pay the piper", such is life. Nothing last forever except God and the souls of men.

Is it possible that the previous owner did the majority of the damage? I'm assuming here that you bought the engine/turbo combination and just put it in your truck without puling the heads to check for damage. Just for the record, I wasn't accusing you of damaging the pistons.

IDIBRONCO said:

Is it possible that the previous owner did the majority of the damage? I'm assuming here that you bought the engine/turbo combination and just put it in your truck without puling the heads to check for damage. Just for the record, I wasn't accusing you of damaging the pistons.

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You're fine. But yeah, I just threw it in there. I'll post pictures sometimes, but my assessment is the damage was starting before I got there I just hammered the nails tightly into the coffin.

To me, it sounds like there was nothing that you could have done to damage the pistons. It's just that someone did in the past.