518-H Bogging down and spilling smoke at angle

[nekovt 0]

Hello, I've got a 518-H / Onan engine that runs just fine, but last year it started to bog down and spew smoke with driven at an angle on the side of a hill. If you drive it back to a level place, it takes a few seconds, but then it starts to run normally again. I tested the cylinder compression last year and it's ok. The only thing I can think of is that it might be the float is sticking open. I just wanted to ask before I dove in to the carburetor.

 

Thanks!

 

[nylyon-(Admin) 7,963]

Is the smoke gas or oil?

[nekovt 0]

I'm not sure. It did have a blue-ish tint to it, but I've seen that before when the float has stuck on other machines.

[nekovt 0]

I went out and found that the air filter is full of oil. It looks like it came up through the breather valve. I checked the oil level and it's fine. I also did "decarbon" this engine 25 hours ago. I also made sure to clean the valve seals while I was in there. 

 

Has anyone seen this before? Thanks!

[Rock farmer 41]

Two things come to mind. You've got something in the carb bowel, water or grit. And/or your crankcase breather is clogged.

Joe

Edited May 13, 2013 by Rock farmer

[nekovt 0]

Hi Joe, Would the carb bowl having grit in it cause oil to come up in to the air filter area? Is the breather the tube that runs up in to the air filter? Thanks!

[Rock farmer 41]

Something in the carb would cause it it run rough when on sloped ground.

Oil coming up into the air cleaner is caused by having positive air pressure in the crank case. That should be vented some place. That vent is not functioning. It could be something else causing your problem. Like a weak fuel pump. Clogged fuel screens or filters. Or too much oil in the crankcase.

Joe

[nekovt 0]

HI Joe, Do you know where the vent might be on this? If it's going up to the air cleaner, I can check it. The fuel pump does leak, it does have a bit of a problem. The oil level has always been good. If there's positive pressure in the crankcase, could it be something other than the vent? The compression tested ok last year and I adjusted the valves, I thought it might be a valve problem but those got cleaned 25 hours ago. Thanks

[Rock farmer 41]

If you follow the hose from the base of the air cleaner, it goes into a square plate on the top of the engine. There should be a spring loaded reed valve in there. That needs to be clean and functioning properly. This info is in the engine manual.

Joel