Oil seal installation advice?

My CH18S Kohler engine walked the crankshaft oil seal out at 600 hours. Luckily, I noticed it and shut it down before it lost all of the oil. The original seal is rubber covered - the seal # is NOK AE7782E. I haven't been able to find an alternative to this seal that will fit the need. What troubles me - the old seal looked real good, but the OD is 2.375", and the block recess that it fits in measures 2.390". I can slip it in and out with my fingers. The new seal O.D. measures 2.378". I haven't tried installing the new one yet, for obvious reasons. Internet videos recommend using red Loctite around the outer mating surfaces, but the Loctite products say "Not for use on plastics", so I'm wondering about using it on this coated seal. The local dealer/mechanic says DON'T use any sealer around the outer mating surfaces. He implied that this seal failure is expected at around 600 hour intervals. I don't like that.

There's lots of good thinkers on this board - do any of you guys have any advice?

Here's a description of the seal and engine recess, as measured;

Seal number NOK AE7782E
1.50" crankshaft measured diameter
2.390" engine recess measured diameter
0.310" measured seal thickness
Double lip seal
Garter spring
Rubber/plastic? coated

As mentioned above - the old seal O.D. measures 2.375"
the new seal O.D. measures 2.378"

Thank you for any advice,
Paul

Is the crankcase ventilation system working correctly?

Bob - I wondered that, and I'm not sure how to check it.

Something sounds fishy. How could a 2.375 diameter seal stay in a 2.390 hole for 600 hours ?

Is there some other method to retain the seal in the bore ?

Was it leaking like a sieve ?

May be able to call Kohler and talk to a tech person for a more suitable seal size.

It does sound fishy Eric. I measured everything with a dial caliper, so you'd think that if the measurements were off on the center of the hole, it would show small rather than large.

No other method to retain the sleeve.

I had been watching the seal area, because it had a slight oily look, but usually added only a small amount of oil every 6 hours or so.

Yes - when it slipped out of the recess, it was leaking like a sieve. Oil got on the PTO belts - thankfully lots of smoke real quick.

I suspect the calipers may be lying to you when you measure the bore.

A way to check would be to cut the old seal, remove the portion of the seal that touches the crankshaft. Then see how it fits in the hole. If there is some resistance going in, you will know the caliper is in error.

Then if you did feel some resistance, your new seal is probably correct as you measured it at 2.378 which would make a tighter fit.

Thanks for the idea Eric. I'm gonna go out and try that right now.

PJH, the National catalog lists an AE7782FO as 470380. 2.378 OD X .312 wide. .003 is the normal interference for a bore in that range. I think you may have mis-measured the bore.

Many thanks to all of you! I tried Eric's idea of cutting the wiping lips off of the old seal. It slips in flush with finger pressure, then tightens up. The bore must be cut with a slight taper. Also - I re-checked the bore diameter, and got a new measurement of 2.380" as far in as I could reach. I must have fat fingered something on my original measurement.

Mike - I wrote your cross reference number down in my manual. Thanks!!

Bob - I'll check the CC ventilation system as soon as it's running again. I'm not smart enough to check it on a non-running engine.

Thank you for all of the good advice!!

Paul

Instructions for checking "crankcase vacuum" are on Page 25 of the service manual.


I hope I linked the correct one!

Something I noticed that surprised me was that they say to lube (if I read it correctly) the OUTSIDE of the seal with engine oil before installation.

Also, it is to be driven in squarely to a specified depth, also covered in the manual.
Official factory service manual

Have you measured the diameter of the old seal? It's not impossible that
an "orphan" seal was originally installed to save a defective engine
block. If in fact the bore is over size, can you find a seal that is 1.500
by 2.253 and make a sleeve for it? This sounds the way to go to me. BTDT

HTH

Thanks for the link Bob! That's a different manual than I have, but for the same engine. After reading about the CC ventilation test and possible causes of problems, one of the possibilities is an improperly installed air filter. I had just put in a brand new air filter about a half hour before the seal popped out. I might have screwed up what should be a simple task. I'll check it out tomorrow.

I got it all back together, but it's too late for the oil on the outside circumference of the seal. I drove it in a little deeper, leaving room for the oil to drain.

Thanks for your help Bob - I click on your posts no matter the subject. You're a wealth of good information!