18.5 hp OHV Intek burning oil

[bob22cn]

My ~17-year old Craftsman lawn tractor (917.275760) with a 18.5 hp OHV Intek engine (engine model 31p777-0299e1 040910ze) is now burning about 1 oz per hour when grass cutting. You can notice very light blue smoke going up hill (presume under load) and smell it all the time.
This seems to have started fairly recently; within the last month or so.
It gets used about 45 minutes/week grass cutting at my home. Since April of this year, it has about 10 hours of use. Our cutting season is roughly April/May-Oct/Nov (I'm near Philly) so that is ~ 24 cuttings @ 45 mins = 18 hours/year. I change oil and filter each year so I don't think a maintenance issue is the cause.

I don't see any leakage on the block or drips beneath on the floor after it being parked.
I'm assuming it is a ring issue and they need to be changed.
Any other suggestions/thoughts on what to check before I order parts and take the engine apart?

I've done a rebuild on a 1960 BS 8 hp. I assume this one not too much different in difficulty?

Thanks!

 

[mechanic mark]

Results

www.briggsandstratton.com

 

[ILENGINE]

With that engine I would say there is a very good chance that you are dealing with a blown head gasket.

 

[Rivets]

I agree with IL. Best thing to do is to find someone with a leak down tester and preform a leak down test on the engine. This will give you a better idea of where your problem lies.

 

[bob22cn]

How does that increase oil burning?

 

[Rivets]

Oil would be sucked into the cylinder from the valve guide chamber, which is the most common place for the gasket to blow.

 

[Fish]

Crank the engine with the valve cover off.

 

[bob22cn]

Thanks! I'll give that a shot. Head gasket is a better repair than rings!

I assume I'll see oil squirting into the chamber on cranking?

 

[pilotbuddy]

Pull the air filter and make sure there is no dirt residue in the carburetor intake. If there is, the air filter was not seating properly and you might need new rings. Otherwise check the head gasket.

 

[Rivets]

Never use any added sealant when replacing head gaskets.