k181 ring end gaps

[Martin 2,133]

just pulled the k181 from kents 875 apart and have a question on ring end gaps.

this engine was an oil burner as anyone that seen kent riding around on it at charlotte last year would testify. i expected the bore to be really worn and there to be ring problems as well.

the bore has absolutely no ridge and although glazed and has a few scuffs looks very nice. i dont have any real accurate measuring tools other than the digital calipers ive had for a while, they are ok, but not what i would call a 'professional' measurement tool.. they do measure fairly accurately with anything ive compared them to and are good enough to tell whether i have a std bore or oversize. one day if i do a real engine rebuild, i should purchase proper equipment.....

i can say its still std bore. the piston thrust face is still above the minimum spec as well, it hardly looks worn at all. in fact the whole engine looks really nice inside.....

im planning on purchasing a set of std rings and giving it a gentle hone much the same as i did on my k241 build that lives on the 1057 now. i couldnt be happier with the way that one turned out and i feel i have exactly the same bore condition with the 875 as i did with the k241.

anyway, like the 241 the 181 has larger than max spec end gaps, the 241 had a large top ring gap and the 2nd and oil werent too bad. that one gave a puff of blue on throttling up but never while running. it didnt burn a noticable amount in the short time i used it before pulling it down..

back to the 181....

the ring gaps as found on this one tonight were.....

top .032

middle .046

oil .062 + ( i didnt bother getting an exact on this one, a .030 and a .032 together were still loose)

from my short memory and because im too lazy right now to go check the max used gap in the manual, i think the top ring was right at max. this engine wasnt a real fire breather, but it did hang on well when it was used as a mower and worker. so i dont think we have any bad compression loss issues ( more than normal for a tired engine, anyway)

the middle and oil ring gaps are excessive and the biggest ive seen out of all the kohlers ive messed around with, which this one is the sixth i think.

so to my question for all of you, or anyone that can be bothered to join in this thread here, is do you think the gaps (the oil one mainly) are a major contributor to this thing using oil?

the last new ring set i did had gaps around .015- .017 when done for the top and middle and the oil was a three piece which made it sort of pointless to measure. i realize the top ring faces more heat than the others and i would expect that to be the largest or at least in the ball park with the rest of them, but it seems that maybe we had some mismatched rings from the factory in this one?

am i on the right track here or totally off course?

[bowtiebutler956 650]

I suppose anything is possible Martin, but so long as the bore has no ridge, and no notable wear, I don't think I would worry about it. So long as the new rings end gaps are within tolerance, you should be good. My Kohler manual is at the shop, and I can't remember what the max spec was for the ring end gap, although .046 does sound way to big. Good luck, and !

Matt :flags-texas:

[sorekiwi 761]

from my short memory and because im too lazy right now to go check the max used gap in the manual,

Lazy damn Aussie..

Sounds like your oil ring is a one piece ring? If so I would suspect that .060"+ gap is not helping things, although there is no number specced for it in the manual. (Yes I did look it up!! ) I've never seen a 1 piece oil ring in a replacement ring set, all the ones I've seen are 3 piece, and they seem to work well at controlling oil (although they do provide a horrible amount of friction).

Actually you had better take a glance at the manual - there are a couple of interesting points - max ring gap for a K181 is quoted as .032 in the front of the manual, but on the ring page it states .027" for styles of piston A and B. Also there is a short paragraph on only a couple of oversizes of oil rings being available, resulting in bigger than normal oil ring gaps (Page 11.10). Not sure if this will apply to you or not, are you going with genuine Kohler rings or aftermarket?

On 3 piece rings I dont usually worry too much about end gap. To be honest I dont think I've ever measured it - I usually just eyeball it to see what it looks like.

Another major cause of oil burning is ring side clearance in the groove. The manual quotes .006" max. Too much side clearance allows the rings to pump oil past them, and it seems to be something that people often forget to check. In the old days we used to machine the grooves wider and then put a thin spacer ring above the actual piston ring to get the gap back down to spec, but on one of these it would be cheaper to get a new piston (or possibly a thicker ring).

[Martin 2,133]

mike, i have the manual beside me while i work on them, i just wasnt going back out there to look it up for this post....

just went and grabbed it and the manual quotes .027 for my style of piston. the ring side clearance is one thing i will check tomorrow, but the rings feel nice in the piston grooves. in fact except for the gaps theres nothing that really seems out of place. the oil ring is a one piece and like you, im pointing at that big gap being most of the problem with oil control. when you look at the design of a one piece compared to a 3 its a wonder they can control oil at all, especially in this case with such a big gap.

i was impressed with the stens ring set i used in the k241 in the 1057 just recently, i may just go that way again. i was thinking about an oem set, but we will see..

the side clearance on the stens set was good with the reused piston in the k241.

[MarkPalmer 81]

JMHO, if those are the end gaps you have with new rings they are quite a bit out of spec. If you are not going to bore this one oversize and just deglaze it definitely use the three piece oil ring, and get a set with the two piece 2nd scraper ring also. These rings have a lot better flex running through well used cylinder bores. Single piece rings with huge end gaps won't do you a bit of good for oil control regardless of the ring groove clearance in the piston, and none of the rings will be able to break in because there is not enough pressure behind them due to the easy means for blowby. I have found that .025-.027 is pushing the barrier for ring end gaps on K181's, even with using multi-piece rings. Now on the other hand if this engine isn't on a tractor you are working for hours on end and is one you just want to putter around on, a little throttle up smoke and some oil consumption might not be too big a deal rather than dealing with the expense of reboring it.

-Mark-

[Martin 2,133]

the ring end gaps i mentioned for the k181 were as found on old rings....

the engine was a runner that as far as i know has never been apart until tonight.

i havent bought new rings as yet.

[MarkPalmer 81]

I have pulled old rings from these engines that had end gaps big enough to drive a Terex Titan through, thus I never really worry about what used ring end gaps measure to. If you test fit new rings and the gaps are within the .027 max spec, you are good to go with just a deglaze yet I would still use the three piece oil ring. They are so much more joyful especially during break-in as you see virtually no oil smoke at all, and maybe only a little oil in the combustion chamber for the first few hours of running.

-Mark-

[smoreau 658]

just stay away from chrome moly rings Martin! you seen my issue with them at the show.