Mower engine smoked and leaking oil?

[311Hemi]

Buddy mentioned his walk behind mower started smoking this past weekend and shut down.....he said it was leaking oil somewhere around the engine after this happened, and out of the exhaust from his description.

Not sure if it still turns over or not.

I have not had a chance to look at it yet.....but could it be a head gasket or something like that? Just trying to get idea on what may have happened and or if it's worth looking at.

There was oil in the machine when it happened.

[Macgyver55]

I'm assuming it was a 4 stroke mower, Briggs or Tehcumseh....Was he using it on a hill where it was tipped to one side? Was the oil level correct? If the engine oil gets up close enough to the crankcase breather for some reason, it then gets sucked into the carb and it will blow out lots of smoke and potenially kill the motor. He can check the oil level, drain if its too high or add if its low. Clean the plug, and try restarting it. If it simply sucked oil through the breather, it should clean up and run ok on level ground. The head gasket is not the problem.

[311Hemi]

Yes, it is a 4 stroke, most likely of one of those brands. I believe the oil level was correct and his yard is flat so it was not tipped to one side.

[Macgyver55]

Assuming that all of that is ok then my first suggestion is to do a compression test. That will determine the next step to take. If it is low, the condition of the rest of the mowor will dictate if it is worth repairing or not.

[311Hemi]

Good idea...not sure why I didn't think of that! Now where did my compression tester go......hmmmm

[Surface Tension]

Have him check the oil level.

A leaking inlet valve(needle and seat) in the carb will let gas run into the crank. That brings the oil level up. The engine will run rough, smoke and push oil out the exhaust.

[311Hemi]

Thanks for the suggestions guys!!!

I gave him some things to check out last night and it sounds like the air filter was clogged with grass and once he cleaned it it seemed to stop losing oil and stopped the excessive smoking. I think the breather tube may be routed to the air filter and that was causing the issue with the air filter being clogged.

[Macgyver55]

Thats a thought.... I suppose, technically the carb is going to draw in air from the path of least resistance. The air cleaner must have become so plugged that it was as easy to pull crankase air as fresh air, so it used both. Must have been running really crappy before it quit..... Glad he got it going!

[311Hemi]

No idea.....it's was just a thought. It was not running very crappy from the sounds of it, so maybe it's something entirely different...I guess time will tell!!!