Chowder

I've got a 98 4.0 Sport. When going to replace the rear main seal, I saw a bunch of metal in shavings in my pan along with a valve spring retainer. I was pretty sure this was a bad thing, therefore I began a complete disassembly. Oddly enough, all of my spring retainers were intact and the only place I saw any sign of metal wear was in the oil pump...

Since I've got the whole damn thing apart, I've gone ahead and just started a rebuild. Where I am stuck now is with my piston rings. The new rings are too large... I bought the standard size but none of the rings will fit. Any ideas why?

aj2494

Too large to fit on the pistons (ID is oversized), too large to fit in the cylinder (OD is oversized), or too thick to fit on the piston? Someone has clearly been in that motor before, so I don't know if you could trust that it still has the original pistons without checking the part number. I would start there.

Chowder

That is my suspicion. I noticed the block had some white paint marks on it once I cleaned it. The standard rings I just bought are too thick, should have clarified that earlier.

Jeep Driver

4.0 rings/pistons come in inch and metric ring sizes.

Yours are metric and you bought inch rings.

I suspect.

Chowder

Alright, I'm trying to see what pistons I have in this thing. Looking at the inside of the piston it says 53020 507 by Chrysler symbol. On the opposite side it reads 52 S 84 12. WTF does all that mean. I'm assuming that some of those are casting numbers, but the rest is greek...

Chowder

This just reaffirms my desire to create the "Punch an Engineer" holiday...

Radi

53020507 is the OEM part number for the metric piston: (If your pistons were PN 4798329, you'd use the 5/64" and 3/16" rings)

cruiser54

Agreed.

And the white letters painted on the block are factory.

XJwonders

Good to know the info mentioned above for when I need to replace the rings on my engine. Thanks!

Radi

Yep. They indicate the piston size for each cylinder. "C" is standard, A-B are undersize, D-E-F-G-H are oversize. Consequences of a worn-out block boring machine.
The differences are very minor, the difference between the smallest A and largest H is only 0.003"
I thought that practice stopped in 1997 when they replaced the Kenosha engine line though. This is a later engine than that?

Chowder

Yep, according to the casting number on the block, it was cast in 98. It is freakin impossible to find these damn rings. I'm about to go and purchase a new set of pistons...

Thanks for all the help!!!

Radi

Here's a few options. RockAuto.com carries these three + some others. NAPA, Autozone, O'reilly, Jegs should have the Sealed Power set.
SEALED POWER E925K
ENGINETECH M38816
DNJ ENGINE COMPONENTS PR1123

Chowder

I finally got the E925Ks. I was really hoping to get the $50 ish kind, but all I could find was the premium. I guess that is not the most terrible choice though.

I'd recommend to anyone rebuilding an engine to go to perfectengine.com and go ahead and get one of there rebuild kits. I thought I could do this a little cheaper, but I could have gotten new pistons, rods, and rings (along with all the gaskets, etc.) for slightly less than what I am up to now...

Well, it's been a huge learning experience. Most of my questions and directions have been answered by the combined experience on this forum. Thanks everyone!!!

Fred/N0AZZ

When rebuilding an engine, any engine trying to go the cheapest route will bite you in the AZZ every time. Did you not have any machine work done on that engine before you rebuilt it?

Chowder

A buddy of mine is a machinist and engineer, he took a look at it and was shocked. He said it just needed a good cleaning. We did notice piston #1 had been replaced at some point, which might explain the good condition of a 190k motor.

Yep, trying to go cheap always costs more in the end.