Kohler Piston Rings

greg r · #1 07-10-2020, 03:46 PM

I have Cub Cadet 1650 with a Kohler K341 AQS. I'm in the process of rebuilding, or rather refreshing it. I acquired a re-ring kit from Pat's which includes a Kohler sourced set of standard size rings, plus all the gaskets, shims, etc.

I'm finally at the point of assembling the piston and discovered the rings are too thick. What I mean is the piston ring grooves are .063"-.064" wide but the rings are .093" thick, that is they are too thick to fit the ring grooves.

So far all the specs I can find are bore size related.

The tractor came with the original owner's manual, and on the back the previous owner/s recorded a service history. In the 1990 the engine was rebuilt. In 1995 a new short block was installed.

Perhaps I have an aftermarket piston? It's Mahle with numbers 95L74 G or 6 8021. Are there year to year production or legacy differences?

Thank you

dvogtvpe · #2 07-19-2020, 08:14 PM

I ran into the same problem with a Pats ring set. I had bought a OS piston and rings, second ring was to thick, called them back and explained the problem and after a short discussion he eventually said he would send a new ring set which I did get, I did have to return the other set

greg r · #3 07-19-2020, 09:21 PM

Yep, this is a rebuild of discovery. I'm finding internal differences in the K series. One is that there were 3 piston styles. My IH Service Manual does not mention it, but the Kohler factory sourced one that covers the whole K line does. Why is there such a variation in new piston prices?

cooperino · #4 07-21-2020, 08:09 AM

Have never purchased rings from "pats" so not sure if there is an actual issue with them.

Did you run a groove cleaner through the ring grooves? Just a thought... It should be done no matter what but I agree .030 should not be a cleaning issue.

dvogtvpe · #5 07-21-2020, 07:14 PM

technology is the simple answer.

greg r · #6 07-21-2020, 09:23 PM

Problem solved. After lengthy emails, the current engine is a short block with a spec number no one recognizes. According to the book, I have a "D" style piston, made by Mahle. Without a recognizable spec number, no one could say which rings to use. One p/n that seemed to go with my piston was Kohler 45 108 10-S but it was listed for a 3.780" bore, more confusion as mine was still at standard 3.750

Onna Hail Mary I ordered the 45 108 10-S. They fit perfectly, in the groove and with book value ring gap.

After a 4WD vacation, it's on to assembly finally.

dodge trucker · #7 08-30-2020, 10:14 PM

yup. Ive bought lots of parts from pat's never an issue. but on the K series there are at least 2 types of pistons/rods and as I remember a "before/after" associated with them. You can use either piston and rod AS A SET in either a "before" or an "after" engine. but no mixing of a "before rod with an "after" piston or vise versa. As I remember the Kohler manual I have illustrates and describes the differences between them so you can ID them when you dismantle a given engine,
but that's not to say someone else hasn't been inside that engine before you and put the "other" parts in them.... I've put the "before" parts in an "after K181/M8 before with no ill effects. Cuz that was what I had here. Still running.