Onan 5500 valve lash

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garyb1st

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How important is the valve lash adjustment and is it a diy type maintenance? We have 1025 hours on the clock and as far as I know it's never been adjusted. In the 5 years we've owned the Pace, we've put about 750 hours on the Onan. Other than shutting down once or twice while driving in extreme heat, it's has performed very well. It gets a lot of workout since we often run with both AC's on. I'm also careful to exercise it monthly when we're not on the road.
 

Chuck c

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Personally if it's running good I wouldn't worry about it. Haven't done it on a generator but on a few lawn tractors and some old farm tractors not bad to do but may have hard time getting to things on a generator.
 

Rene T

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How important is the valve lash adjustment and is it a diy type maintenance? We have 1025 hours on the clock and as far as I know it's never been adjusted. In the 5 years we've owned the Pace, we've put about 750 hours on the Onan. Other than shutting down once or twice while driving in extreme heat, it's has performed very well. It gets a lot of workout since we often run with both AC's on. I'm also careful to exercise it monthly when we're not on the road.
I don’t have a rv genny so this is new to me and may sound stupid but what is valve lash? Are you talking about the thrust clearance on the main shaft?
 

Pedro Dog

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Valve lash adjustment is messy, and easy to screw up, but after so many operating hours, it's worth checking. Normally, if the gap is too big, the engine is noticeably louder. If the engine is quiet, I'd be tempted to skip it.
 

Rene T

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Valve lash is the clearance between the valve tip and rocker arm. I'd check it. It isn't difficult to do and requires only a feeler gauge, open end wrench and your hand (turn fan to TDC fore each cylinder/s.
Oh the intake and exhaust valves. DUH!! I never thought of them.
 

RRR

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It isn't particularly hard to do and doesn't take that long. Feeler gauge and a sparkplug socket. The one cylinder is hard to get the plug out. In my case I have a 3/8 drive socket that has a hex end on it, get the socket on it then turned it with a wrench as I didn't have room to get a flex bar with the socket on the plug.
 

DonTom

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If the engine is quiet, I'd be tempted to skip it.
Some say it's the opposite. Too loose only means noise-but no damage. Too quiet can mean the valves are open longer and overheating.

At least with my 1971 BMW motorcycle where I check the valve clearance every couple of years or so.

-Don- Auburn, CA
 

Pedro Dog

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One has to be careful that the piston is absolutely TDC. I usually stick a dowel into the spark plug hole and go back and forth on the crank till I feel the piston TDC. Engine has to be completely cold, let it sit overnight. The feeler gauge needs to slide in and out but slightly rub then tighten. Too small gap and the valves will not sit in the head properly and valve seats will overheat and burn. Too small gap will have no play when running at operating temp but will not clatter. Clatter will damage the rocker arm and pushrod as well as the cam. I've rebuilt many engines where the cams and tappets where distorted.
 

Heli_av8tor

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The clearance on mine was excessive with less than 1/3 of the hours on your engine. You’ve put it off long enough.
It’s not that difficult. But if after watching the videos you are not comfortable then hire it done.
 

Old_Crow

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Some say it's the opposite. Too loose only means noise-but no damage. Too quiet can mean the valves are open longer and overheating.

At least with my 1971 BMW motorcycle where I check the valve clearance every couple of years or so.

-Don- Auburn, CA
I've been reading up on my new-to-me Honda. The older models, with set screw and lock nut adjustment get loose when they go out of adjustment and make noise. The newer ones, with shim-and-bucket adjustment get tight when they go out of adjustment and can burn valves by not closing completely.
 

DonTom

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with shim-and-bucket adjustment get tight when they go out of adjustment and can burn valves by not closing completely.
Many of my motorcycles are shim & bucket. They rarely go out of adjustment and even when they do, it probably isn't enough to make any difference.

But I prefer the Harley M8 method. Hydraulic valves-nothing to adjust. HD does a few things the right way.

-Don- Auburn, CA
 

garyb1st

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The clearance on mine was excessive with less than 1/3 of the hours on your engine. You’ve put it off long enough.
It’s not that difficult. But if after watching the videos you are not comfortable then hire it done.
Did you look at your because of hours or were there performance issues or it just sounded loud?
 

Heli_av8tor

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I thought there was more tappet noise then there should be. It ran quieter after adjustment.
I didn’t notice any difference in performance.
 

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