B&S Intek 23HP blowing smoke

[shpxnvz]

Hi, I have a Husky lawn tractor with a 23HP B&S Intek engine that's about 6 years old. Been running fine until end of last season when it started blowing blue smoke out of the muffler.

I pulled the carburetor and cleaned it, it had oil in the intake manifold (guessing from the breather tube?). I tried starting up again (without breather attached) and it started smoking after about ten or twenty seconds.

I've pulled the heads now and don't see any gasket damage. This is what things looks like. Any ideas on where to look next for the problem?

Thanks!

 

[motoman]

shp, Can you move the piston around in the bore? Try a .001" feeler strip between the piston and bore, then a larger one, then a larger one and judge the withdrawal force as none, some, heavy. Let's say the withdrawal force for .001" should be be heavy. Pic five shows cross hatch hone marks. Don't think they should be there after 6 years. Has someone honed and refitted the same piston/rings? Bores and pistons are very fussy. Does look like some oil is entering chamber. IMO

 

[shpxnvz]

Thanks for the input, I'll try the feeler gauge tomorrow. Definitely no piston work done on in before, I've had it since new. Mower has about 150 hours on it total.

 

[bertsmobile1]

Can't see anything wrong there.
Try a vew gasket and a new valve stem oil seal.
Inlet valve sucks oil down the valve stem.
Plug looks a little lean so give the carb a once over while it is off.

 

[Rivets]

I suspect a blown head gasket, but can't tell from your photos. Do you still have both head gaskets and can you post pics of both sides of each gasket?

 

[ILENGINE]

The second picture of the head with the head gasket. It looks like some discoloration around the center top near the push rod cavity divider. I would like to see the other side of that gasket. Just looks like evidence of blown head gasket in that area.

 

[shpxnvz]

shp, Can you move the piston around in the bore? Try a .001" feeler strip between the piston and bore, then a larger one, then a larger one and judge the withdrawal force as none, some, heavy. Let's say the withdrawal force for .001" should be be heavy. Pic five shows cross hatch hone marks. Don't think they should be there after 6 years. Has someone honed and refitted the same piston/rings? Bores and pistons are very fussy. Does look like some oil is entering chamber. IMO

Turns out my smallest feeler strip is .003" and that one won't slide past the rings at all. Not sure if I can find .001" and .002" gauges locally to buy or borrow, if so I'll try those too.

 

[motoman]

shp, The feeler test is ONLY for piston fit. Do not try to force past rings, Your (relative) low hours, sole ownership, suggest the cross hatch is the factory machining. Don't bother with the .001 " strip. Wait to reassemble and do compression test. The pros are suggesting oil up pushrod galleys and accross gasket into chamber, I guess.

 

[Tinkerer200]

Blown head gasket is almost always between the cylinder bore and push rod gallery, often on the engine block side and may only look like a pencil mark. Sounds like blown gasket to me.

Walt Conner

 

[shpxnvz]

shp, The feeler test is ONLY for piston fit. Do not try to force past rings, Your (relative) low hours, sole ownership, suggest the cross hatch is the factory machining. Don't bother with the .001 " strip. Wait to reassemble and do compression test. The pros are suggesting oil up pushrod galleys and accross gasket into chamber, I guess.

Ah, ok, well the .003" definitely fit between the piston and bore on both cylinders if that indicates anything. I'll be getting some better gasket pics up too in a few.