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Discussion Starter #1
Hey guys, i have a 416-8 with the Onan with 649 hrs. It runs like a top. However the welch plug behind the pto and above the crankshaft rear bearing plate is leaking oil and it looks like it vibrating ever so slightly in and out when it running at full throttle. I know the camshaft is on the other side of the plug. I would like to know if I can remove and replace the plug without pulling the cam which would be basically a major teardown of the engine. Will installing a new plug solve the leak and what kind of sealant would be best to use. It has some kind of reddish sealant on it now that is starting to deteriorate so I'm sure its contributing to the leak. Thanks in advance.

Tom
 

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Tom,
I had the exact same problem.
The guy who repaired it said that there's not much you can do.
He put some JB weld on it and said it could last or not.
Not long after that the coil went out and I didn't want to put anymore money in that motor.
It's now repowered with a 24 HP Honda GX-670.
Good Luck.
 

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Discussion Starter #3
Well thats a pretty crappy design. I just got my new plug in the mail today. If that doest work then I was thinking of tapping the block and having my dad machine me a plug that screws in. I really cant believe they would design it so stupid like that.
 

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When you install the new plug make sure the bore it fits in is clean and use a THIN bead of high temp loctite around the plugs outside edge. Very thin! Set in place and smack it dead center with a blunt faced punch or a 3/8 socket extension. You might have to hit it a couple times but don't push the center in so it's concave.

You want it to look dented, not dinged but not smashed in either. Too far and it could rub on the cam. Wipe off any excess loctite and then put a little RTV around the mating joint.
 
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