How much piston damage is too much?

[Maximan1]

My pistons look they were probably on the receiving end of a failed turbo. Some were worse than others, but they all had chunks of metal embedded in the faces.

Ring lands and grooves are all good, I got all the chunks out of the face with careful use of a dremel tool, am going to smooth them out tomorrow in preparation for reassembly.

How much damage is too much? I know the piston tops are pretty thick, I have a melted piston where I can see the oil passage, seems to be about 1/2" between the top of the piston and the oil passage. I know these pistons were run with the embedded pieces for quite a few miles, as I didn't even realize they were there until I removed the heavy carbon buildup.

No hot spots, a little skirt scuffing, and pistons are not in the budget right now. How much of a risk is it to run these? Are pistons a weak point for the OM617a?

Thanks
Max

[Clemson88]

I had a 3.8L gas MB engine jump time and piston(s) met valves. I pulled one piston and rod assembly and took it to a machine shop. The machinist looked at the underside of the piston for deformation and told me he'd replace it.

He'd been doing engine machine work for NAPA, wasn't an experienced hand with MB but he was near retirement after 30-40 years there so I took his advise. I really jury rigged the assembly because I'm poor. I bought a piston, tried it in the hole and it moved a bit so I assembled the engine and it ran fine for a while. I didn't frequent this site often and didn't know how to search the archives. I was a 50+ year old rookie.

The 380SE's of the mid 80s weren't nearly the engine as the diesels of that era so it didn't last long anyway but to my knowledge the piston was never the problem. It was fueling system and electronics which caused me to yank the engine and put an om617 in the body.

It seems to me if there are many such questionable pistons in consideration the probability that at least one of them is not worthy for use. I would be reluctant to assemble an engine using questionable components. No, I wouldn't do it so you should probably make sure by a more accurate means than asking someone to make a guess.

It just seems like too much expense and time to risk but I'm sure if you took photos of the tops and undersides of those pistons, posted them here and asked these good gentlemen you one or more of them would advise you with opinions as accurate and useful as you will find anywhere.

You will also need to try and stick to this thread, answer questions, ask for clarifications and make yourself available to those who can help guide you through this process.

[rocky raccoon]

That is a lot of work to install questionable components. I would not do it. As a minimum, you will have hot spots on your pistons that would be vulnerable to further damage. You may want to closely check your cylinder walls also.

Unless you are prepared to disassemble again and reassemble with new pistons in the near future, don't waste your time.

[t walgamuth]

You would be surprised how thin the tops of the pistons are. The tops of the turbo pistons are hollow because of the oil squirters which spray oil up into the hollow top.

I'd round up a set of good used ones here. I have some but an mot sure how many.

[t walgamuth]

I'll get him to look at them today.