A list of questions while I'm into it this far

[TNBrett]

Well, I knew it was at least a possibility that I would see something I didn't like when I pulled the heads. There was some scoring in the cylinder walls, and like @frankewrench suggested it did seem worse in 1, 2, 7, & 8. So, I'm going to go ahead with 6.9 cooling mod when I put this back together. Any way, this is the really scary part.

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All together it looks like 6 of the pistons have similar cracking. This really knocked the wind out of my sails. It really shocks me to see all this now with how well this truck was running when I pulled it into my shop. On one hand I know where I have to go from here, but on the other, I'm not sure I want to.

 

[IDIBRONCO]

Maybe you can get lucky and find an affordable, running engine to put in your truck while you rebuild this one? Maybe you're not interested in that approach?

 

[Big Bart]

Well for being 30 years old, turbo charged, and been around the block a few thousand times the head gasket leak is not a big surprise. Just a reminder to all of us to use distilled water and change your coolant every 5 years. It helps prevent corrosion and leaks over time.

Now 6 cracked pistons is scary, at least you did not throw half a piston through the block. I don’t recall others on this site reporting multiple cracked pistons. What’s your thought on the cause?

Do you run your egt’s up high? Pull lots of grades? Pull big loads frequently?

 

[The_Josh_Bear]

That's wild, 6 cracked pistons all in the same spot. Dang. Like @Big Bart said, good thing the block is all in one piece still! Boo on the damage.

 

[IDIBRONCO]

The 6 cracked pistons makes me lean toward someone putting gasoline in it by mistake one time. I may be wrong. I'm also certainly not accusing TNBrett of doing this. I have seen it done before. The truck came back for warranty work on the engine. The owner swore up and down that that didn't happen, but it sure was gasoline that was coming out of the hard line between the filter and the IP when I was taking the engine back out of the truck.

 

[TNBrett]

So, this week was busier than I had hoped for, but I still managed to find time to look into things a bit, and ponder what I want to do with this. Based on apparent parts availability, I have 4 different options the way I see it. I should add that I have spent time this week convinced that each one of these options was definitely the way I should go. From what I can tell, the only pistons and rings that are available are standard size, and .030" over. Bear in mind with these options that I haven't taken the oil pan off yet, but I did plasti-gage several crank and rod bearings 15k miles ago, and everything looked good and was on the tight end of the specs.

My first option is to have the block sleeved and run standard pistons. I would install the reman heads and studs I have already, along with new crank and rod bearings. I would consider cam bearings if needed, and if available (that doesn't look promising). At that point, it would seem like sacrilege to run this engine w/ the pump and injectors that I currently have, so add those to the bill too. And, let's not forget about an intercooler also. The number I got from the machine shop was $2000 to bore, press in sleeves, re-bore and hone, and deck the block. Add that to all the other parts, and it's an expensive undertaking. For me, I cannot justify this option for this truck. This is counter to the mission of this truck for me. My goal with this truck has been to be an affordable truck that I can rack up miles on commuting back and forth to work, while still being reliable, capable, and comfortable. It's a tool for me. If I go this route, I will end up with another truck that I feel like is too nice to put 40-50k miles a year on. I've already got one of those. The other thing is that I like this truck, but I'm not sure I like it that much. If it were a crew cab 4x4 SRW, it might be a different story, though I still wouldn't want to use it up commuting.

The next option is simply to cut my losses and throw in the towel. I could sell everything off as a basket case project, or piece by piece, and probably not take that big of a bath on it. There are a few problems with this. I don't like to admit defeat. I do still like the truck. And, I still feel like the truck can be made to do what I'm asking of it.

The third option is to clean up the deck surface, slap the reman heads on it, and drive it. This kind of goes against everything that I know, but I drove this truck into my shop. I'm not sure what caused the cracked pistons, but I know that since I've had it, it's never been fed gas, and I've never seen EGT's over 1100*. I wouldn't be surprised if those pistons have been like that for some time. The heads that were on this motor were in pretty sad shape, and I would have to think that a fresh set of heads would have this engine running at least decent. The issue is, for how long? FWIW, I rotated the engine on the stand until the driver's side bank of cylinders was level and filled the dish of a couple pistons with diesel fuel.

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They held fuel like that for over an hour. That was interesting to me, and makes me feel like the cracks are not all the way through the pistons.

The last option, and the one I'm leaning towards, is to do a more budget minded rebuild. I don't really think it needs .030" to clean up the bores, but if that's the only thing available, I guess that's what she would get. The machine shop quoted me $400 to clean, bore, and hone the block. I would Clean up the deck surface by hand and check for flatness. I'd also replace the crank and rod bearings. I would keep running the pump and injectors I have for now, but at least pop test the injectors to know what I've got. My concerns with this plan are the potential for cavitation to appear when it's bored, and whether .030" over would be detrimental to the strength of the cylinder walls. I will probably try to piece together some sort of intercooler setup sooner rather than later if I go this route.

So that's where I'm at right now. What are your thoughts?

 

[Shadetreemechanic]

I have some good pistons (6 or 7) from a 7.3 I tore down and am not likely to put back together any time soon. I believe they are standard but would need to pull them off the shelf to verify.

 

[hacked89]

. 030 is max OK by international spec. My. 040 over cracked a wall after probably 10k miles so I wouldn't do that. I looked for it in the thread but why can't you drill hone yourself and throw used pistons in with new rings?

 

[TNBrett]

I have some good pistons (6 or 7) from a 7.3 I tore down and am not likely to put back together any time soon. I believe they are standard but would need to pull them off the shelf to verify.

I appreciate your thinking of that, but mine is a IDIT so the pistons are different than an N/A. They have a larger wrist pin and a keystone shaped top ring. There is also deep enough scoring in a few cylinders that is too much to clean up with a ball hone. Therefore in my case new pistons equals bore or sleeve.

 

[TNBrett]

. 030 is max OK by international spec. My. 040 over cracked a wall after probably 10k miles so I wouldn't do that. I looked for it in the thread but why can't you drill hone yourself and throw used pistons in with new rings?

I think the scoring is to deep.

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I can feel it with my finger tips. I don’t have to use a nail. I’ve done the ball hone thing before on other engines, I think this is too bad for that.

 

[Big Bart]

TNBrett

You suggest you want a cheap truck to commute with and guessing toss toss when it’s had it. VS taking the depreciation hit on a new truck.

So I would not suggest you get too deep into your IDI. As you said it’s a tool not the truck of your dreams.

Suggest -

1) Put the heads on and run it. If you make it 12 months, perhaps parts are available then, so pull and rebuild. Perhaps you find an engine in the meantime. Your current one dies you swap or rebuild then. Perhaps before the 12 months you loose the tranny or rear end and decide it’s time for a new used IDI truck anyhow. If it goes 6 months it was worth the say $1,500.

2) Keep the heads. Sell it, part it out, or keep it as a parts truck if you plan to buy another IDI. You are not throwing in the towel you are cutting your losses, which are two very different things.

The challenge -

1) Parts will likely hold up your project and you end up with 10-15k miles on your good truck.
2) You will be another 5-10k into this truck. So now you will feel you have to keep going deeper if something else goes wrong
3) If anything goes wrong with the rebuild you now have a tougher decision to make.

Two years ago you would have better options, but COVID has screwed up the world as we knew it.

 

[TNBrett]

I’m pretty well settled on the idea of doing a .030 over rebuild on it at this point. I guess I’m putting this out here to see if I hear a resounding chorus of “don’t do it, it’s a terrible idea because of X, Y, or Z”. If all the parts in the world were readily available and I did it at .020 over, is that really that much better?

 

[hacked89]

It's no different it's within machinist spec for the engine. The only reason I wouldn't do it is because my machinist isn't cheap and it's more cost effective to swap the engine in for a promar. If it makes you feel assured i'll take a pic from the international book when I'm in the garage later.

 

[IDIBRONCO]

Since you're talking about using this mostly as a daily driver, I don't see any reason why you couldn't find a running N/A engine and put in your truck to use for now until you can get this engine rebuilt. A N/A engine will easily handle the boost that the Factory set up puts out as long as you haven't modified it to get more boost out of it.

 

[Shadetreemechanic]

Come get the block I have with the pistons. My memory is it was a hone and go, but its been a year or so since I looked at it.
It threw a rod on #8 but the block is ok. Crank is yard art and I already have a spare motor so its just taking up space now and I have a mercedes 240 motor that needs to go on the engine stand.
I will make you a great deal on all of it.