B&S that started smoking

[White 03]

Engine in question is a B&S 15.5 HP vertical crankshaft single cylinder OHV on a Sears riding mower. Probably 5 to 10 years old but not used that much, mainly in the summer once a week for an hour or so. It recently started blowing blue smoke. I never noticed much if any smoke then one day I notice considerable amount of blue smoke especially when under a load or accelerating up to full RPM.

This year I tried some 10-30 that I had so the first thing I thought maybe it didn't like the multi-grade oil; changed it back to 30 weight and it still smokes. I drained gas to be sure I didn't use the 2 cycle gas by mistake. I put 2 oz of Lube Control in oil, ran that for an hour and changed the oil to see if a stuck ring would free itself but so far not much change. It is not any worse but it is not much better.

Today I cleaned the little square PCV but really couldn't tell if it had a little or a lot of oil in there. A little oil was in the rubber tube but not any showing on the intake manifold or carb. Spark plug is very oily but it seems to run strong I have never changed it though. I looked under the valve cover and it is very clean; I don't know if was always that way or if the Lube Control and oil change made it that way.

Engine still runs good and makes good power as far as I can tell.

So I am now thinking maybe a broken ring or bad valve guide or seal. Short of a teardown or a leak down test is there anyway to tell if it is either of these?

Any other things to check or reasons why it started this?

Thanks

 

[Steve S]

The engine may be wearing a bit or how is the oil level is it over filled? or try a 15w/40 or a straight 40 I would try to do the easy stuff first then run it till it drops. Air cleaner been checked?

 

[MolaKule]

I have found that the PCV/reed valve is usually the culprit. Replace it if you can.

 

[Jelly]

...I've never seen a B&S smoke a lot unless it was really, really old and had some several mechanical problems.

With that said, I'm running Pennz. Long-Life 15w-40 in a 20hp vertical-crank, L-Head, V-Twin engine. Had generic 30 weight in their before, and had consumption issues (probably burning off too!) after a few months of running.

Try some good 15w-40 (Pennz. Long-Life, Delo, Delvac) and see what happens.

 

[White 03]

Thank for the replys.

Steve S
I have the oil level down below the upper mark so I don't think it is that and I cleaned the air cleaner foam and the paper looked good. I hope it is not wore out yet but I guess I will see.

MolaKule

I tried to find a new PCV but couldn't find any shops with one in stock. That was my thought also. So I just cleaned it out the best I could with carb cleaner. I think I will try somemore places and see if I can find a new one and then I can be sure.

Jelly and Steve S

Before I give up I will try the 40 weight just to see if that will cover the problem.

Anyone ever have a problem with the oil getting past the valves on these engines?

If it mainly does it when the engine is under a load would that be an indication of rings.

I think I will try a new PCV first for under $5.

Thanks