Could the O-ring that holds the cap on be bad/dried out/worn and not holding the cap on tightly? That was the condition with the used engine I put in my 317.

 

As Vinnie said the first thing I would do is replace the cap with a new one. Roger

 

Thanks Vinnie and Roger. I called Kohler and they came up with one number for the cap -- which changed a half dozen times back to the original part number -- with a new description of dip stick. I ordered a new filler cap (Dipstick they call it). Figured it was a Kohler item, but just out of curiosity I looked it up on the Deere parts web-site and came up with a Deere number. the number changed a couple times and came back to being serviced with two parts, a cap and a tube. Now I am wondering if maybe Deere came up with a different idea for the filler cap then Kohler. I guess we will wait, install and see what happens. if it does not seal up I might have to try the Deere two piece replacement. Kind of makes me wonder if i would have been better off going right to Deere on this one. Has anyone replaced theirs with one or the other by chance? Thanks again!

 

Bob,
These oil-fill plug caps will eventually pop, even for an engine with proper crankcase vacuum--a very frustrating experience for an otherwise clean engine. The early versions of the cap with a lower metal "splash guard" were more reliable. Whenever I work over a KT17 or M18 engine, even if the oil-fill plug seems good and tight, a small diameter, long spring is added to be sure the plug does not pop in a couple of years. Alternately, a 3/4" pipe nipple with threaded cap is used to replace the plug (to clear the air filter housing, the nipple is cut at about a 7 degree angle and re-welded to give an angle offset). Of course there is a chance that the engine has positive crankcase pressure and a check using the manometer described in the Kohler service manual could put everyone at ease.
Harold

 

Here's a photo of the two types Harold mentioned.
I replaced it several (10?) years ago and no problem since. The newer valve cover was added a few years after that. I'm pretty sure the new one without the baffle was around $20 at the time. It appeared to be a cutoff dip stick from a later K241 that was $6! It still had burrs from the sawcut when purchased.
Anyway, the old Series I in mine no doubt has excess crankcase pressure, but the filler cap holds OK.

tommyhawk

 

Thanks guys! I got the new one this morning from Kohler. Looks like the one on the left in Tom's picture. Do you think we should grind the washer-baffle off the old and weld it onto the new plug-stick or try it as Kohler provided? Harold, where do you attach the spring for your idea?

Thanks again! Bob

 

Bob,
I just beat the rain and finished mowing with this JD 317. The springs I have used are conveniently attached just below the oil fill plug to the little carb support bracket, or to a wire hook placed behind the nut. I happened to have 3-4 of these springs on hand, but it appears that Ace hardware stores have very similar springs. These are 3/8" diameter with a 3" body and with looped, non-closed ends. Other sized springs could be made to work. I personally would not bother to weld the baffle on the new plug, as the spring will hold things in place when the rubber hardens or shrinks some year, or the engine decides to do an odd belch. Just for the benefit of other folks who may look at this, I would not recommend using the spring to hold a very loose oil fill plug in place, as the rubber may be so bad as to allow an air leak into the crankcase.
Harold

 

I like that Harold.

 

Kohler has threaded(both ends)filler pipes for other engine apps. I know these won't blow out.

 

Update...Thank you all very much!! It is cured!! After the new plug, mowed the whole 2 acres without a hint of oil anywhere. You guys are amazing. I never dreamed it could be something this small. We are going to look for a spring as Harold suggests...just to play it extra safe. my friend is absolutely beside himself. Great job on the advice guys. Thanks again!
Bob