Check out the #2 and #6 pistons. The other 4 pistons looked great, but these 2 look terrible.

QUESTION FOR ENGINE BUILDERS.......I'm going .040" over. How much bigger should I make the cylinder than the piston???? I'm thinking .005" over???

 

I thought the cylinders were replaceable sleeves? Looks like you blew a ring land on the pistons? What scored them up so bad?

 

I'm really not sure. I know the engine has had the head gasket replaced at least once from overheating, and tore one waterpump up. So it could have been from running too hot. The rings were good on the pistons, no odd wear on them. The main bearings and rod bearings showed some wear but not too bad.

 

Yeah, might have had some high EGT's.. I don't know much about diesels.. learning (: subscribed!

 

Is there an engine manual that your using for the rebuild?

After doing a little research, I know they sell rebuild kits for up to and including 40 over, so I assume you would punch it out at 40 over and install the right kit.

Dont know for sure

 

Yep, got a complete kit with .040" over Mahle Marine Pistons. No engine manual, the most important tq specs are listed here in the FAQ section.

 

Our motors are known as some of the "throw away" diesels. Heavy duty truck motors can be sleeved, ours can't.

 

I would go with more that 5 tho on the piston to wall. That is basically the stock clearance. Like was said awhile back, top ring gap is important too, when you get them extra hot. I am sure they know, but they need to fit the bores to the pistons.

You can put repair sleeves in the block, if needed.

 

It's pretty simple. Look up the original bore spec and go .040 over. That is why they send you .040 over pistons. The proper clearance is automatic. Your shop will know what to do when you tell them bore it .040 over.

 

I'm almost certain they can be sleeved.

 

Hold it

If I read this right, he thinks you cut .045

The best thing is to get the pistons first and match them to the bore. The pistons already are slightly smaller than the bore. That's how it's done

Yes it can be sleeved, but that could be allot of money. If that's the case, you are better off buying a used motor and use that block

 

What you need to do is look at the tolerances in the FSM and try to hit the middle of the range. You should not guess on this stuff. The Non-IC engines are not sleeved from the factory, but any engine can be sleeved. I am not sure when they started sleeving the engines from the factory. This is where a good machinist really earns his money. There are tolerances for rings, pistons, ring gaps, out of round, you get the picture. I would take it to a good machinist and he can tell you what it needs. Bore it out the MINIMUM that will bring it into tolerance...Mark

 

no!!!

That's a good way to need custom pistons or new block.

 

One other thimg, I ALWAYS check the work of the machine shop with feeler gauges, for ring gaps, ect., and plastigauge, for bearings and such. I had a really good machinist get mad at me for asking for plastigauge when I picked up my parts from him, until I reminded him that sometimes parts are miss boxed or mis-marked. During reassembly, it is important to make sure everything still turns after installing or tightenning something, so that you know what caused the problem. I took 2 years of advanced engine rebuilding in school. I learned 2 things, How to build an engine right and that I wanted to be a firefighter...Mark

 

X2 that is tantamount to guessing...Mark