1989 Bolens ST120 w/ 12HP B&S I/C burning oil BADLY!!!!!

[sean'sengines]

So, we bought a new Toro Z4200 zero turn mower because of this. We were tired of this old machine. I'd like to fix it if possible, and then sell it. I'm thinking that it needs piston rings, which I REALLY don't want to do.

What happens is that as soon as you put the engine under any stress, (turn the PTO on, start moving the tractor with the hydro) it bogs down and BLOWS blue smoke like crazy, then won't start cause of all the oil getting into the carb. When this happens, if you have the air filter off, you can see oil come into the carb. What can I do about this to fix it?!

HELP!!!!!

 

[sean'sengines]

no one has any idea?! c'mon!!!

 

[jeff]

Sounds like bad rings to me. Does it have any compression?

 

[sean'sengines]

Yeah, the compression is ok. I'm kinda figuring that it needs rings. not something I really want to do. Basically involves rebuilding the whole engine right?! I also thought it may be the oil sending valve unit? If I'm calling it by the right name anyway....

oil sending valve kinda under and to the left of the carb?!:

 

[KennyV]

oil sending valve kinda under and to the left of the carb?!:

I think you are looking at the crank case vent... can't tell your picture is way too small...
I'm with jeff ... it is most likely bad oil rings, giving you lots of oil pulled onto the cylinder & burning....

If everything else is OK... replacing the rings is not going to be that bad of a deal... :smile:KennyV

 

[sean'sengines]

Ok then, so, to replace the rings, I basically need to take the whole case off, and take the crankshaft and the piston out, put in a new set of $15 rings and then put it all back together. Wow.

 

[KennyV]

Ok then, so, to replace the rings, I basically need to take the whole case off, and take the crankshaft and the piston out, put in a new set of $15 rings and then put it all back together. Wow.

Not so bad... I one time had to take the track AND final drive off my (over 20,000 lb) Cat ... just to replace a $100 seal... you should have no trouble with that small engine...
Plus when your done it should work a LOT better than it is now. :smile:KennyV

 

[sean'sengines]

I just need to learn how to do the rings exactly. I'll do it some day when I'm outta school in a couple weeks.