# Onan Governor noise???



## Trailhead4x4 (Nov 22, 2010)

The Gravelys are just dropping like flies recently! My 8163 with Onan B43M engine has started making a strange tapping noise which sounds to me like it is comeing from the governor area. It also started surging yesterday at light throttle which makes me want to think the new noise is a governor issue. Is this something I should look into, or a is a little bit of noise from that area normal? It almost sounds like ball bearings inside a hard plastic container if that makes any sense. Thanks again for any advice.


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## Mickey (Aug 14, 2010)

If you've not worked on the Gov of an onan flat twin I can tell ya it's not a simple job. Don't recall any plastic covers on my onan. The design does use ball bearings as the weights for the gov. The gov is built on to the end of the cam and is part of the timing gear. To replace the gov you have to pull the cam and press the gear off the end. Don't recall exactly how the cam and timing gear are indexed but there is no pins or keys. I ended up taking the cam down to the local JD dealer and have them make the swap. Their small tractor mechanic sad it was the first time for him to have an onan that far disassembled. Pretty easy to damage a cam bearing so be REAL careful. I ended up having to replace one of the cam bearings. Spent ~$125-$150 on parts including the one cam bearing. Nothing more than an aluminum ring with precision ID/OD @ $25. Parts included new timing gear with gov, new head gaskets and several more gaskets. Seemed to recall having to pull the engine from the frame to help make the job go easier. Twas a several day job.

Engine running like new again when finished but its not a job I'd like to entertain again. Good luck. OH, that was 8-10 yrs ago.

In the attached pic that is of a single cyl engine but the gov design is the same for the twins.


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## jhgky448 (May 4, 2013)

easy way is remove engine drain oil turn pto end of engine down remove timing cover check all bearings and other parts of govoner whish i could up load pictures from shop man. bearings have to be asembled in correct way dont disamble engine any fauther than necassary if you can find local shope read manual would be best bet valve to lose "might" be the soundyou are hearing hope this helps good day


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## Richard-tx (Jan 30, 2011)

What you are hearing could be normal....or not. Until the engine is running smoothly, you won't know.

Surging is usually caused by a too lean condition. Try choking it a little at a time and see if the hunting goes away. If it does then the carb is at fault. If you cannot adjust the idle mixture to get rid of the surging/hunting then remove the idle mix adjusting screw and give it a shot of carb cleaner or some compressed air. If that does not fix it, then take the top off the carb, mop up the excess gasoline out of the bowl and blow it out. Note the color of the gasoline. If the gas is yellow, dump the contents of the tank, flush the lines are install a new fuel filter.

Also look closely at the brass orifice and make sure it is clean. Below you can see a dirty orifice










The B48 is one of the most foolproof engines Onan made. I have yet to hear of a governor failure on any Onan.. If the governor is at fault, Bob the Used Onan Parts guy has camshafts and more at very reasonable prices.

http://boomersonanparts.com/

Give him a call. He is a nice guy.

Richard - who has Onan engines on all five of his 4 wheel Gravelys.


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## Mickey (Aug 14, 2010)

It's rare but it can and does happen that the gov will fail. After my gov failure I couldn't keep a constant engine speed but I'd not describe it a engine surge.

Will have to hear back from trailhead to bring us up to date on what he has found.


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## Trailhead4x4 (Nov 22, 2010)

I never got as far as getting into the governor. After getting the covers off, I was running the engine to listen more closely to the noise, and it just stopped doing it and smoothed out. I use this tractor almost every day, it doesn't sit, and always has fresh fuel in it. I guess I'll just continue to monitor it and see what happens. I mowed about 2 aces of grass with it this weekend, and have to convert back to the broom to sweep a parking lot today. Thanks for the tips and advice everyone, it is very much appreciated!


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## Trailhead4x4 (Nov 22, 2010)

Noise is still gone, but some performance problems still exist. Occasional over speed if I throttle up too fast, and surging at less than full throttle. Also doesn't seem to throttle up fully.


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## Richard-tx (Jan 30, 2011)

#1 problem topday is the e10 gas and water. I think you have water laying in the bottom of the carb bowl. Take a sample of gas and look at the color. If it is yellow, dump all the fuel, flush the lines, clean the carb and give it a fresh tank of gas. The problems is so severe here that I am running av-100 gas. That resolved all of my water, bad gas issues.


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## Trailhead4x4 (Nov 22, 2010)

I drained all of the fuel and refilled with 93 from a local Marathon (the only place I know of around here that sells gasoline without ethanol) and the issues still exist. The tendency to "run away" occasionally when throttling up or if it is started with the throttle open a bit worries me, it has never done this before. Also still doesn't seem to settle in to the same throttle position each time when fully open. The power loss isn't a big deal with the sweeper, but when I'm mowing bigger areas with 2nd gear it is noticeable, and if it doesn't get resolved, the wet heavy snow we get here will be a pain with the blower this winter.


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## Trailhead4x4 (Nov 22, 2010)

I also use Star Tron Enzyme fuel treatment in all of my small power equipment such as chainsaws and weed wackers, it is supposed to negate the negative effects of ethanol. Since I've started using it, all of my small engine equipment seems to start more easily, and run through the warm up much better. I've never run it in the Gravely though, it has always seemed to be pretty content with it's fuel.


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## Trailhead4x4 (Nov 22, 2010)

Still having performance problems with the onan. Moving snow is such an arduous task anymore. At full throttle, even the smallest amount seems to bog it down. I am now almost certain it is a governor problem now, I was able to run it under load with the air cleaner off for a few minutes, and the throttle plate does not open when the RPMs drop under load. I'm not sure if this is an adjustment that can be made or if there are bigger problems. Should I be able to fully open the throttle when the engine is not running? I can on my 12 hp Kohler tractors, but not one this onan. Frustration is setting in with this one.


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## jhngardner367 (Apr 5, 2011)

It sounds more like a carb problem,although a sticky governor could cause it,also.
One thing you could try,before tearing into it,is some Marvel Mystery oil,in the crankcase,when you change the oil.
Use about a pint,and top it with the normal grade of oil.and run it a few times,to see if the problem still exists.
It could be it has some varnish, on the governor.
Also,check the throttle plate shaft, for wear.Just disconnect it from the linkage,and flip it a couple of times,to check for binding.Then wiggle it side to side to check for wear.


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