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Discussion Starter · #1 ·
Built a 18 hp onan in my 446 after a long talk with Boomer and following his recommendations used a John deer block with an oil filter. Everything went smoothly and it runs well. But it’s developed a strange issue. When running at speed mowing it will gain some RPM then drop back to normal. I’ve checked everything short of pulling the timing gear cover and checking the Governor ball/ cam asy. Any thoughts? Or do I tear into it?
 

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Have you checked the linkage between the governor arm and throttle lever for play? Briggs and others have a spring on the linkage rod hooked to both levers to take out any play due to slop between the holes and rod. A quick test is to put a rubber band on the levers to hold them tight.

Cheers,
Gordy
 

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Keep this in mind if nothing else solves your problem. I've found numerous times when Onans had symptoms such as yours that the spider on the cam gear which separates the governor balls is loose on the hub. Early ones were a metallic part and I only saw a few failures, easy to spot the problem because they were cracked where they were pressed onto the gear. Later production went to a plastic or nylon material which was retained with a loctite type material. I've seen quite a few of these that are no longer bonded to the hub and slip causing a difference in speed between the cam gear and the governor assembly. Just something to consider if you do not find any other problem.

Bob
 

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Onan Master, new and used parts.
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bob & club
the plastic flyball spacers were NEVER glued on.
they relied on a press / interference fit.
LOTS of them failed,
the extended tab spacer solved the problem.

onan knew about this problem, that is why they started putting
the notch in the gear.
BUT, they started the plastic in dec.1985, and the notch in about may
of 1986.
in jan 1992 they they started installing the extended tab spacer.

i have been helping to solve this problem since dec 2012.

thank you. boomer
 

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Discussion Starter · #5 ·
Boomer once we get back above 45 degrees here I’ll be giving you a call to get what ever parts I’ll need. Stay warm.
Ed
 
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