Crankcase Oil Leaks

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RBW
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Crankcase Oil Leaks

Post by RBW » Sat Apr 30, 2022 8:19 pm

My engine seems to be trying to push oil out of every available opening. It had not run for probably 30 years. Cylinder bores did not look too bad, really not that much corrosion. Been running it quite a bit lately and noticed that the magneto is weeping oil out of the vent cap on the lower side. Previously it had been leaking oil out around the timing adjustment bolt slot due to a broken piece of the magneto housing, which I filled and had stopped leaking. The governor seems to be leaking a bit of oil. I also notice oil in the carburetor inlet tube, J tube, and a little at the bottom of the air cleaner housing. The spark plugs are a little wet, but not bad.

So, is this a dirty crankcase breather reed valve, blow-by due to worn rings, or something else? I keep 2.5 qt of oil in the crankcase, at the top of the operating range. Put about a pint of Marvel Mystery Oil in last time. Engine runs great, starts easy, seems to make lots of power for what it is. Thanks for any recommendations.


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Re: Crankcase Oil Leaks

Post by Chuck W. » Sun May 01, 2022 1:08 pm

Chasing oil leaks is another one of the joys of owning a mule. Good rule of thumb; if it is not leaking, it's probably out of oil!

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Re: Crankcase Oil Leaks

Post by RBW » Sun May 01, 2022 3:09 pm

I was starting to assume as much. One seems to spring up as soon as another is corrected. It does seem, however, that my engine is trying to eject its oil at a higher rate than normal. Maybe I'll try cleaning the breather.

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Re: Crankcase Oil Leaks

Post by markrdje » Sun May 01, 2022 3:39 pm

Wheels are another good oil leak source.
change user name to mark

Chuck W.
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Re: Crankcase Oil Leaks

Post by Chuck W. » Mon May 02, 2022 7:22 am

I also notice oil in the carburetor inlet tube, J tube, and a little at the bottom of the air cleaner housing. The spark plugs are a little wet, but not bad.
You may have a cam bearing trying to turn in the block, might want to read Charles's article on this problem: viewtopic.php?f=148&t=265091
Wheels are another good oil leak source.
One problem is incorrect wheel seals. Many people use the National 473455 seal, but it's a single-lip seal. John Emery has the correct original style double-lip seal. Also new O-rings on the lifting rings.

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Re: Crankcase Oil Leaks

Post by RBW » Mon May 02, 2022 8:00 pm

So, does a failed cam bearing "clatter" in a way that sounds like really bad valve train noise, and get worse when the oil warms up and thins out? I'm starting to think that's exactly what I have.

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Re: Crankcase Oil Leaks

Post by Chuck W. » Tue May 03, 2022 9:36 am

I have never had an issue with the cam/cam bearing, but I would assume the oil pressure would drop as the engine warmed up due to the excessive clearance. I remember talking to Charles several years ago and he indicated that, in his experience, the cam bearing problem was pretty common. I guess I need to purchase a new cam and cam bearing to put in my "someday" stash!

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Re: Crankcase Oil Leaks

Post by RBW » Tue May 03, 2022 7:37 pm

I wonder if I can see anything related to the cam bearing from the bottom of the case where the oil pan mounts. I need to replace the oil pan gasket and remove a broken oil pan bolt. Perhaps I can figure out something that way.

Chuck, are you and I the only ones wrenching on Mules these days? The forum seems awfully quiet.

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Re: Crankcase Oil Leaks

Post by ltsimp » Wed May 04, 2022 5:55 am

I only wrench on my Mule when it needs it or for the usual Maintenance. It seems this forum runs hot and cold. A period of less activity then it gets quite busy. Perhaps the periods of greater activity are spurred on by a topic of common interest. Who knows. I do find these Mule forums to be invaluable.

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Re: Crankcase Oil Leaks

Post by Chuck W. » Wed May 04, 2022 9:36 am

I don't think you will be able to see the cam bearing from the bottom, although you might find some aluminum shavings in the oil pan.
Chuck, are you and I the only ones wrenching on Mules these days? The forum seems awfully quiet.
Does seem kind of slow here. There is a Facebook page that seems to be active, I read it but don't post there. I'm not going to get started posting on another forum, and frankly, from some of the questions posted there, I don't think I could help much :roll:

My mule has not been moved in a long time, it's on wheel dollies in the corner of the shop! I do crank it every few weeks, but it has really become a "work bench"!
Since my wife has started her chemotherapy, I have had to suspend any customer work in the shop to take care of her. I have a couple of jobs pending, but will be next year before I can think about them.

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Re: Crankcase Oil Leaks

Post by tbied2 » Wed May 04, 2022 3:59 pm

..... i had the cam bearing problem in one of my mules. puked oil out in a lot of places. i even had oil in the bottom of the air filter canister. and into carb. it was a fairly easy fix,, just kinda time consuming. the hardest part was getting the camshaft back into that little slot in the back ...... good luck,,,,,...,,,,,,,,,................... a quick photo of how the bearing retainer allowed the bearing to spin around,... new bearing on cam,........

Image79CD7F45-C08C-4F67-9995-EF54576DBF2F

'''''''''''''

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Re: Crankcase Oil Leaks

Post by Mike_W » Sat May 07, 2022 2:33 pm

I had this happen to me one time. Oil leaking out of every seal imaginable. It was my own fault. I had closed the crankcase breather valves while doing some work on the engine and forgot to reopen them. The crankcase created so much pressure inside it pushed oil out everywhere. If it has been parked that long, maybe the valves were closed for storage. Don't know but it's a simple thing to check.
Mike White
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Re: Crankcase Oil Leaks

Post by RBW » Sat May 07, 2022 5:09 pm

That is a good thought. I did check all the breather valves, and had rebuilt them when I had the machine apart. I got a new cam bearing and will plan to remove the timing cover and cam to see what is going on in there. There is a lot of what I would normally think was lifter noise, but I think it may be originating from something related to the cam bearing, but we'll see.

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Re: Crankcase Oil Leaks

Post by RBW » Sat May 14, 2022 7:36 am

Well, the cam bearing is definitely bad. It and the retainer look like the picture above. The bearing bore in the block is actually scored as well - two rings that correspond to the two sections of the bearing on each side of the oil groove. The location of the grooves on the passenger side makes sense based on the radial force from the crank gear in that direction as it rotates the cam gear. I notice that, as shown in the pictures above, the new bearing does not have the additional small groove near the flange that the retainer holds. I wonder if this is to provide extra material to secure the bearing in the block - either a design improvement or to compensate for a scored bearing bore. Could also just be a manufacturing change. I should have it back together today and will see if the oil ejection issue gets any better. Breather was dirty, but shouldn't have been clogged. Fair amounts of oil in the intake horn, J-tube, and even a little at the bottom of the air cleaner. Spark plugs were more oily last time I pulled them, so that doesn't seem quite as bad. I am also interested to see if this resolves the rattle that the valve gear seemed to be making - like a very bad valve tick that got worse when the oil was warm. I picked up on a bit of a "ping" from the cam and/or gearing as I rotated it manually, and this matches with the nature and location of the noise. There was visible slop in the cam bearing, though not as much as I would have expected.

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Re: Crankcase Oil Leaks

Post by Chuck W. » Sat May 14, 2022 4:27 pm

Interesting, please let us know how it works out. Are you going to Loc-Tite the bearing or pin it?


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