Oil Consumption Issue
 

I have a cub 2518 that has a CH18 in it. It has approx. 750 hours on it. I had an issue with some minor oil consumption but not major. Then I had a push rod issue happen so I ended up replacing the heads, valves, and seals. All is new. Then a major oil consumption issue appeared. After mowing the yard, approx 2 hours the oil barely registers on the dipstick. So I replaced all the components associated with the oil breather system. Still no change in the oil consumption. It smokes pretty badly. The compression on both cylinders is in the 150 psi range. I have checked compression on a cold engine, and a warm engine. There is no change. After mowing for 30 minutes, or mowing for 2 hours I check the oil, and it barely registers on the dipstick. What could the issue be? Could it be rings? I don't where to turn with this.

Sounds like a blown head gasket forcing oil into the cylinder. I don't care the compression shows good, because a lot of times it does when the gaskets blow in that particular spot. I don't know if you planed the heads or not, or what brand of gasket you used..... but do it again, and use Kohler gaskets and plane the heads. 750 hours isn't enough time to wear the rings out unless the engine has been abused, or ran with no air filter. :beerchug:

I did not plane the heads when I replaced them. I used Kohler heads, and head gaskets when I replaced everything. It has been a well maintained, and and properly filtered engine.

So should I pull the heads off and start over with new gaskets?

Sounds like you need to pull them and have a look. If you didn't plane them that's likely the issue
You said you used Kohler heads... New ones ?

yes, all parts were new Kohler parts, including the head gasket.

Jon or someone else here would know better if new kohler heads require any work. I think I would check them regardless before installing. How long did you run it before the issue? And how were they torqued ? Re torqued?

It was right after I installed them that the heavy oil consumption started. I torqued them to spec, but have not retorqued them.

Ok, I pulled the heads back off. I planed the heads, and block with a file to insure that they were both perfectly flat. I replaced the head gaskets with new Kohler gaskets. Still no change. It still smokes, and used most of the oil again after mowing. Any other ideas, or avenues to pursue? I am at a loss.

Did you take pictures of them when you took apart? Did you see signs of a blown gasket? With the engine at idle. If you pull the dipstick is oil shooting out?

How did you plane the heads to ensure flatness? On a piece of glass? Same question for the block?

Have you checked that the vent line is clear and not pinched?

I did not use a piece of glass, just the file going across the head in all directions. I did notice the head gasket appeared to be oil soaked though. No oil is shooting out the dipstick. The vent line was replaced when i did the oil breather. It does smoke when running. I seem to get more smoke when i throttle up, or down. I also get smoke when i engage the PTO for the blades.