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Damp patch on top of crankcase 912uls

  • shay.king
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5 months 3 days ago #21590 by shay.king
Damp patch on top of crankcase 912uls was created by shay.king
Hi everyone,
Recently I noticed a damp patch on top of the crankcase on my 912uls [s/n 4428028 Spring 2002].

With SB-912-029 in mind I went looking for cracks but didn't find any.

After a 25 min ground run today I tried to see the source of the leak, initially there was nothing and then, after about 5 mins, I saw a droplet very slowly appear from the crankcase join on top centre. It was just enough to wet the top of my finger when I wiped it away. Then another droplet appeared appeared and I wiped it away again and so it went on.

During the ground run I could only get max RPM to 5050. Previously I had prop pitch adjusted to get 5300 RPM at full throttle stationary on the ground.

I checked prop pull through force with the engine cold and got a figure of 32 ft/lbs.
I checked it again immediately after shutdown and it was only slightly higher at 37 ft/lbs.
This was without removing any spark plugs.

The engine starts easily and runs smoothly.

Any opinion or advice on the above would be greatly appreciated.
Shay.

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2 months 1 week ago #22575 by shay.king
Replied by shay.king on topic Damp patch on top of crankcase 912uls
Just for information on the leak that I had.
After mulling over possible options to fix this problem I took the engine out and brought it to a Rotax repair centre.
When the crankcase was split there was evidence of fretting near where the leak was, see attached photos.
New crankcase fitted, engine re-installed and ground runs look good.
Can’t say the same for my bank account though.

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The following user(s) said Thank You: Gyrochook.

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2 months 1 week ago #22577 by Roger Lee
Replied by Roger Lee on topic Damp patch on top of crankcase 912uls
Was this a 2006 or 2007 engine?

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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2 months 1 week ago #22579 by shay.king
Replied by shay.king on topic Damp patch on top of crankcase 912uls
Roger, the engine is a 912uls manufactured Spring 2002 s/n 4428028.

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3 weeks 1 day ago #23003 by Coggers
Replied by Coggers on topic Damp patch on top of crankcase 912uls
Seems there are quite a few of us having to cash out a lot of money for this fault. I've just had the same painful experience...
www.rotax-owner.com/en/rotax-forum/4-gen...-my-experience#22977

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