Onan 16 h.p. engine running rough

LeoinMI · Nov 2, 2016

I have an Ingersoll 3016 with power steering. The engine is an Onan 16 h.p. The tractor has power steering. It has been running fine until the last time I used it a couple of weeks ago. The engine lost power and back fired. I nursed the tractor back to the garage. I let it set for about ten minutes and restarted it. It ran fine for about ten minutes and then ran rough again. I am guessing it may be an electrical problem verses a carb adjustment. Any thoughts out there ?

Billy Shafer · Nov 2, 2016

Make sure it is running on both cylinders. Also I would clean and check the points. If it has them. Need to know what you have. Model and serial number.

LeoinMI · Nov 2, 2016

Thanks Billy. I'll get the engine numbers. Just seems weird that the engine runs fine until it gets warmed up or hot. I thought it may be a bad coil.

da.bees · Nov 3, 2016

I think Billy's suggestion might tell you alot.

Billy Shafer · Nov 3, 2016

I looked up that mower. It has the P216 according to the spec sheet. Electronic ignition system.I would check for a bad plug or plug wire.Coil could be going out. Also check the valves. Make sure oil is up to proper level. I will check but I believe that model did have a two section intake manifold. Some got out of the factory with a bad seal. Got hot and would open a small crack. I have the information on the engine if you need anything. Carb could be dirty. But I need to know what the Spec letter is. Because with spec G Onan went with a California carb. Not to be repaired so Onan didn't sell gasket kits. But if you are careful with the gaskets you can clean them.

Should be something like this
P216G-1/10464 A A is the spec letter.

LeoinMI · Nov 3, 2016

Thanks Billy. I believe the gaskets were replaced by the previous owner,so there could be a leak there. I'll get the Spec letter today and re-post. I'll also check the plug wires and spark plugs to see if all is good in that area. I may just order a new coil just so I have I have an extra on hand. Again ,thanks for all the info.

gab · Nov 3, 2016

Could be as simple as bad spark plug dropping out when it heats up, isn't going to be a cheaper fix and that's where I'd start.

Ken Combs · Nov 3, 2016

The Performer series have an occasional problem with the valve seats coming loose. Yours may be in the early stages of that. when cool the seat fits the block recess well, but when the aluminum heats up the seat becomes loose.

a leakdown test should confirm , or not. Or just pull the heads and do a decarbon as it's recommended at 500 hour intervals anyway.

That way you can inspect the valves and seats and be sure.

Billy Shafer · Nov 3, 2016

Ken brings up a good point.Something to check. I worked on a BFA. Where the owner had changed the intake gaskets. Ran for a half hour just fine. Then would go nuts. Surging, backfire and running real bad.Found he had put the gaskets on wrong.

LeoinMI · Nov 3, 2016

O.K. Guys, I pulled the spark plugs and cleaned them and checked the gap.I got good spark and the wires are in good shape. The Coil seems to be fine. The battery is some what weak,..so a new battery is in order before next spring. I sprayed carb. cleaner down the carb. I checked the engine oil,..(It was a little low so I added some). Blew all the dirt and grass off the engine with my air compressor and blew out the air cleaner. The hydraulic oil was low so added to that and checked for leaks,..did not see any. Removed the screen and cleaned off the hydraulic cooler with my air hose. Ran the tractor after I did all this and it seem to run fine. I plan to replace the spark plugs,air cleaner,change the engine oil with a filter and tighten up any hydraulic hose clamps that seem to be loose. I am letting the tractor set over night and check for leaks in the morning. I put a piece of clean cardboard under the tractor so as to spot any leaks.I'll post back after I get all this routine maintenance done next week. It seems the tractor needed a good cleaning up from the summer mowing season.

LeoinMI · Nov 3, 2016

The spec. Letter is C. on the engine. I cleaned the engine up today but am going to replace the spark plugs, air filter,and give it an oil chenge next week. Seems to run fine for now. I'll keep you posted if it acts up again.

kevinstuff · Nov 11, 2016

Valve seats could be the problem, I also
Have 16 onan same same kinda problem
U describe, upon tear down , there was grass
Clippings plugging up cooling fins , which I
Think the motor overheated and most likely
Loosened up valve seats, you may be running
To lean under load , check valves and seats
Adjust valves. And carb

Onan 16 h.p. engine running rough

LeoinMI

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Billy Shafer

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LeoinMI

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da.bees

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Billy Shafer

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LeoinMI

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gab

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Ken Combs

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Billy Shafer

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LeoinMI

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LeoinMI

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kevinstuff

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