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afisher3
09-10-2009, 04:38 PM
I have an Onan 20KW gnerator that has a small leak at the mating of the engine and the generator. Has anyone opened up that part of the unit? Is there a seal or just a gasket? Thanks for any help.

Al
67' CPMY
doc g
09-10-2009, 04:54 PM
could be a rear main seal leak , if so it requires you splitting the gen end off the engine to get to it ..................................Pat
SKYCHENEY
09-10-2009, 06:28 PM
Its the rear main seal. I just replace my 20KW Onan with a new Norpro. The old genny is sitting in my barn. When I get ambitious, it's going on Ebay.

Removing the gen end is not an easy job. You first have to remove the stator and then the rotor and baffles can be removed. Lastly, the flywheel will have to come off. Then to get to the rear main, the casting that is also the rear motor mount has to be removed. I'd figure about 15-20hrs labor to R&R that seal in total.
Trojan
09-11-2009, 07:39 AM
Its the rear main seal. I just replace my 20KW Onan with a new Norpro. The old genny is sitting in my barn. When I get ambitious, it's going on Ebay.

Removing the gen end is not an easy job. You first have to remove the stator and then the rotor and baffles can be removed. Lastly, the flywheel will have to come off. Then to get to the rear main, the casting that is also the rear motor mount has to be removed. I'd figure about 15-20hrs labor to R&R that seal in total.


I don't know about the 20KW Onan but most generators drive off the opposite end from the flywheel. It's a lot cheaper and easier to couple to the front end of the motor then the flywheel. But if Sky has had his apart he would surly know. Bill
SKYCHENEY
09-11-2009, 09:03 AM
Mine was as MDL4 engine. Others may be different.

http://i134.photobucket.com/albums/q81/skycheney/memday09004.jpg
Nonchalant1
09-12-2009, 06:41 PM
Its the rear main seal. I just replace my 20KW Onan with a new Norpro. The old genny is sitting in my barn. When I get ambitious, it's going on Ebay.

Removing the gen end is not an easy job. You first have to remove the stator and then the rotor and baffles can be removed. Lastly, the flywheel will have to come off. Then to get to the rear main, the casting that is also the rear motor mount has to be removed. I'd figure about 15-20hrs labor to R&R that seal in total.

Wow! Quite a job if it's just leaking a little as stated, I guess I'd just put diapers under it. I know some of you will think that's too easy.

Doug
Jaxfishgyd
09-12-2009, 08:24 PM
I bought 200 diapers online for .34 cents each and that included ups delivering them to my boat......Last time I checked, West Marine wanted $1.99 each, plus tax !!!!
eze2bme
09-12-2009, 08:56 PM
Charlie ... Who did you order the diapers online from for $.34 apiece? Thxs.
Jaxfishgyd
09-12-2009, 09:39 PM
I see the prices have gone up since I bought mine in 2007....

http://www.absorbentsonline.com/economy_oil_spill_cleanup_absorbent_pads_and_rolls .htm
Newhattyowner
09-15-2009, 12:59 AM
Has anyone tried an oil additive like LUCAS stop leak or like kind product to stop a leak at the rear main seal on a genny?
yachtsmanbill
09-15-2009, 06:39 AM
Has anyone tried an oil additive like LUCAS stop leak or like kind product to stop a leak at the rear main seal on a genny?


Over the years Ive used "mechanic in a can" with fair success. Its esentially like adding 1-2 oz of brake fluid to the oil. It'll soften up a hard seal and even get a worn one to swell up a bit.
It wont last forever... it may evaporate from the heat (?) ws