Cub 1994 18hp V Twin with exhaust leak noise

[rforster]

I have a 1994 cub cadet with a 18 hp kohler v twin When shutting it down it sounds like you can hear the compression in the motor two or three strokes. Sounds like exhaust compression. It is not a backfire. You can also hear this during it running. Seems to be on the right side of engine when sitting on the mower. To better describe it it sounds like air being released. Any suggestions what to look at. 702 hrs on engine. Heard nothing while mowing, but I had a time when it seemed like it was running out of gas, going downhill, shut it down and checked but it was 3/4 full. Started it again and it ran fine. The engine sounds fine ohter wise and runs smooth.

Thanks

Ray

 

[CajunCub]

Check that side head gasket, maybe it is starting to leak.

 

[rforster]

I need to know if I can do a compression test on this engine and be accurate? According to the manual it may have the ACR on it. However I did do a compression test and the right was 125 and left was 175. If this is accurate the I know what I need to do. The question is does the ACR release both heads at 700 rpm starting or just one side, if this motor is equipped with it. This is a 1994 Kohler ch18s.

Thanks
Ray

 

[CajunCub]

Just to be clear....You should have BOTH plugs removed at the same time when checking the compression. With that large of a difference between the cylinders, I'd say you do indeed have a blown head gasket or a burnt valve "as in the seating portion of the valve face is unseatable". Probably the intake valve....You need to check the valve adjustments on both intake & exhaust first. As far as the compression release, that is not the problem, and there is 1 for each side.

 

[rforster]

From what I understand there is no adjustment on those valves they are hydraulic lifters, would you not see smoke or oil on head on a blown gasket.

Thanks for the explanation on the ACR in both cylinders. I have not yet removed the head to take a look at the valves, until I was sure that it just wasn't the exhaust gasket which is half worn out. I forgot to list that on the last post. I did have the plugs out on both sides.

Thanks for responding cajuncub

 

[gator6x4]

For some reason Kohler engines like to blow the head gasket on the right side (Setting on seat) The hardest part about the repair is removing the sheet metal to allow for the removal of the head. I would repair as soon as possible damage to the engine could occur. Exhaust gas is hot and could melt parts exposed to the exhaust gas. Kohlers Web site has a PDF manual that is downloadable. I would suggest visiting the site and reviewing the manual. The compression reading you are receiving indicates a problem with the cylinder. To confirm it is a head gasket fabricate a pressure injector out of an old spark plug and a air chuck or rent one from Auto - Zone, or O'Rileys. Injecting compressed air into the cyldinder with the valves closed will allow you to run your hand around the edge of the cylinder head and feel for the air leak. Or if you want to get fancy inject smoke and look/see where the leak is at.

 

[rforster]

The exhaust and head gasket were bad. Replaced and the sound is gone. New problem is the mower wants to quit running after cutting for a while, acts like it is running out of gas. Stops then and starts right back up, and then in a little while does the same thing again. Filter seems to have gas in it when it stops. I noticed that there is a small leak occuring around the oil seal on the block behind the PTO, could this be causing the pto to get hung up and bog down the engine acting like it's running out of gas. I do not seem to have this problem when just running the mower with out the deck engaged. One other thing would be is it normal to have air blowing or sucking on the valve cover that has the oil fill cap when you take it off. Any help here.

Thanks

Ray

 

[CajunCub]

Ray, sounds like you may have done all that work on the gaskets for nothing....yes they indeed needed it but, if you have oil pushing out the shaft seal "now" AND pressure building under the valve covers (Not normal alone)....while loosing power & shutting down. I really think that you've got a broken compression ring on that cylinder too. Because broken rings do all of the above. They will allow the engine to run breifly, but under a load the crankcase builds pressure and forces out oil and lose of power.
What I've seen in my experences is...when a engine back fires on shut down, there are times that it blows an exhaust gasket, then times both the exhaust & head gasket, and then there are times when it is so servere that it can do that & crack or even break the rings. The best way to tell is to run another comression test again. If there is a drop in pressure on that side of more that 10-15 psi, you have got a ring problem. I really can't see anything else that acts that way. Sorry.....:frown:

 

[rforster]

I will do another compression test. The engine never backfired. According to the kohler manual the problem could be in the crankcase breather and reed, this can do the same thing forcing pressure to the seals and oil dip stick and I believe that this will also cause the pulse gas pump not to work properly. Keep in touch we will get to the problem sooner or later.