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pstraub

CCKB Rear Main Seal

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pstraub
It is looking a lot like the rear main seal on the Onan CCKB engine in my AC 720 is leaking... a lot. Oil is being blown out the front while running, especially on the right side, but also on the left. The entire engine is soaked in oil, and it is pooling on the top of the engine. Lifting the hydraulic cooler, the bottom of the engine is soaked, presumably where the oil is leaking out. My question... Should I just pull the engine to fix this? If so, is there anything else I should be doing while I have the engine out? Peter Straub AC 720

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Guest
Gunk it and check the filter bolts before pulling the engine.

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pstraub
Gunked it last night before mowing for 1.5 hours to see if I could track down the leak, but the oil is getting blown all over, and not very obvious where it is coming from. I just checked the filter housig bolts per your suggestion, but they are nice and tight. Also checked the pressure sender, and it seems fine. ..Shroud, rear PTO, wires and three bolts, and this engine is out. I may as well yank it. My problem... I can't find an engine manual for download anywhere. I just put a bid on one on ebay. Can anyone send me some pertient pages from the a CCKB engine manual to change any/all of the main seals on this engine? Peter Straub AC 720

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UCD
Onan no longer permits the free distribution of their parts catalogs on the Web. To purchase an Onan Parts Catalog, please contact us at: Don Hillman Inc. 1714 West SR 84 Ft. Lauderdale, FL, 33315 954-467-6755 phone [url]http://www.donhillmaninc.com/[/url]

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Guest
Find the all leak before you pull the enging or run it on the bench.

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pstraub
Pulled the engine. The rear main seems fine. But there are a lot of other gaskets in the area that look like they could be trouble... the oil filter housing, rear cover, even the oil pan. I am betting now on the filter housing gasket. Now that it's out, though, I'll replace them all. I took the rear cover off and the gasket just shredded into pieces. May as well do rear main, oil filter housing, rear cover, pan, and the two valve cover gaskets. Give it a good degrease and pressure wash, and bench run it to make sure it's sealed up all proper like. Peter Straub

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Guest
Make sure the copper washers are on the bolts that hold the filter housing on.

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pstraub
Update: 10-4 on the copper washers. Upon disassembly , it is clear that this engine has been apart before, and re-assembled with lots of gasket maker and blue RTV.... the source of the oil haemorrhage are obvious. Replaced pan, rear cover, valve covers, oil filter housing, intake/exhaust, and rear main seals. Also made a cover for the now defunct fuel pump hole. Did some mowing, and the oil leak is licked. While I had the engine out, the neighbour two doors down stopped by. He has an AC-720, and his son who lives across the back way has a 620 with a honda transplant, and a resulting spare CCKB that he was wondering if I needed any parts for since he now had a spare. We chatted tractors, lamented how we should have jumped on the AC in the local paper for $900 that came with tiller, mowing deck and snow blower. Looks like I''m going to fit in with the neighbours just fine. At least Peter Straub

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D-17_Dave
Way to go Pete. And if you have a chance to get ahold of the spare CCKB you'd better do it. BTW, did you get your neighbors signed up on Simpletractors yet? lol We always are looking for more die hard tractor nuts.

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