Huge Blue Smoke Cloud from my Kohler CV22S

remedy26September 18, 2009

I have a '98 Craftsman 46" tractor mower that has always run great until last week. The engine is a CV22S, type 67544, family SKH624U1G2RB. I've always done service on it annually. Last week as I was mowing my place the engine started laying a blue smoke cloud that would have made the 1st Calvary proud. I mean this thing was as big as my house by the time I got the mower turned off. Probably in error I decided to restart it. I had to choke the heck out of it, but it finally started again and was still smoking as before so I shut it down again. Later, I held my hand over the exhaust as I turned the engine over using the starter and there not enough compression lift my hand at all. I'm hoping its just the head gasket that blew-out, but I haven't had a chance to tear it down yet for a close look-see. Any ideas on what else I may be looking for?

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You probably nailed it by the blue smoke. Putting your hand over the exhaust outlet of the muffler while cranking will not really prove anything for a number of reasons. Go to the Kohler engines website and download your free copy of the service/technical manual for your engine, save a copy to your computer.

    Bookmark   September 18, 2009 at 1:27PM
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Thanks mownie...I'll go to Kohler and get that manual.

    Bookmark   September 18, 2009 at 2:16PM
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I've got the I'm waiting for the head gaskets to arrive and some dry weather here in central Oklahoma. My reasoning for the hand/muffler test was to check for compression...or lack of it. I guess the correct way to do that would be to get a compression gauge...Once I get a chance to remove the head(s) and hopefully find a bad gasket I'll repost to let you know my findings. Wish me "GOOD" luck!
Thanks, Jim

    Bookmark   September 23, 2009 at 10:37AM
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***"I guess the correct way to do that would be to get a compression gauge"***
Actually, even that is really not an accurate assessment of compression (or leakage of compression) on these engines. Some of these engines feature an Automatic Compression Release (ACR) which lowers the compression during cranking for esae of starting. The ACR renders a cranking compression test inconclusive at best. Kohler prefers a cylinder leakdown test to determine how well a cylinder is making and holding compression/combustion.
Here is my standard poorboy leakdown test.
A "cylinder leak down" test (or reasonable facsimile) using compressed air can be done to identify the route by which the compression is escaping. To do a "bona fide" leak down test requires a "percent of leakage gauge". A close approximation of the test can still be done if you have (1)Compressed air available, and (2) a threaded adapter fitting that will screw into the spark plug hole and also plug in to an air hose, (3) a means of securely locking the crankshaft/flywheel in the "TDC of compression stroke" for the cylinder to be tested. Locking or holding the engine from turning when compressed air is applied to the cylinder is very important, both for personal safety, and, for accurate test results!! Actual testing is simple and amounts to "listening" to determine where the air is escaping when compressed air is applied to the cylinder through the spark plug hole adapter fitting. As follows: Turn the crankshaft/flywheel to position the piston of the testable cylinder to TDC of the compression stroke. Here's a hint, the valve train for both valves of that cylinder will place the valves in the closed position. You determine this by watching the tappets through the open valve compartment (if applicable) or by watching the valves with the valve cover removed. When both TAPPETS or lifters, are retracted toward the camshaft, and you can detect clearance between the end of valve and the tappet.....lock the flywheel in place so the crankshaft can't turn when air pressure is applied to the cylinder. Failure to securely lock the flywheel against moving could result in personal injury if the crankshaft rotates in reaction to the compressed air applied to the cylinder. In addition to the locking of flywheel, keep your hands away from the flywheel and crankshaft until air pressure is disconnected from cylinder. With the flywheel locked securely, thread the adapter fitting into the spark plug hole (be sure to have one of the spark plugs with you when you buy the adapter fitting) and tighten it so it can't leak air. Connect the air hose from a source of compressed air (60psi to 90 psi recommended). IF, there is a loss of compression, you will hear air leaking from somewhere. Carefully determine where the air is escaping by using a 2 foot length of hose or tubing. Place one end of the hose or tube close to an ear (but not inside your ear) and then move the other end of hose to the exit portal of the exhaust system. If air is heard loudly escaping here, the defect is in the exhaust valve or seat. Check the intake valve condition by moving the end of the hose to the throat of the carb (throttle must be held wide open, choke butterfly open, and any crankcase breather hose must be disconnected from the carb, (if carb is mounted to the intake manifold). If carb has been removed, place the hose into the intake manifold. If air is heard loudly here, the defect is in the intake valve or seat. If you do not detect air escaping from either of those places, check to see if you can hear air escaping from the crankcase breather hose (or pulse hose if impulse fuel pump is present). If you hear air escaping from the crankcase breather hose, or pulse hose, the defect is in the piston or cylinder wall. Always remove the compressed air supply from the cylinder before unlocking the flywheel. A leaking head gasket serious enough to cause loss of compression would be obvious without any test equipment, and you know it right away when the engine is running.

    Bookmark   September 23, 2009 at 1:12PM
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I'm doing one of these (CV 730S, 25HP) for similar reasons. It's in a 2003 GT5000 which I just picked up on cl. According to the previous owner mice had gotten under the blower housing and built a condo, and he replaced the head gaskets. Over the Summer he complained that the engine was losing power. He completely dissassembled the engine looking for the cause which he initially thought was pistons and rings, as well as the cylinder bores. I asked if he had freshened up the cylinder heads with new valve springs and he had not done so. If a CV overheats for any particular reason, the valve springs are compromised and you will loose compression, and power.

On this particular engine the pistons are perfect, the rings are sharp, and the cylinder bores still have cross-hatching from the factory. My rebuild will include new valve springs and valve job, head gasket and bolt kits, and carb rebuild.

    Bookmark   September 26, 2009 at 8:25PM
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WELL...I've got the air and I've got the know-how...but I don't think I want to go out and start buying special tools at this stage of my life. As good as this mower was running when...and how it acted when this whole thing started...I think I'm going to roll the dice and just replace the headgaskets. I've got 2 kits coming and of course I'll give everything a visual while it torn down and if anything looks suspect I'll check it out then. This is going to be a winter project anyway. Thanks so much for your great input and I'll be back in touch to let you know how it turns-out.

    Bookmark   September 29, 2009 at 1:32PM
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I have a GT5000 with a 25 HP Kohler. It started to smoke real bad so I changed the oil & oil filter then I let it run for 15 minutes to burn the oil out of the muffler. It runs like a new one now. The mower is 7 years old and has 200 Hrs on it. The oil filter has to filter right or it will cause the engine to smoke.The engine has never used oil.

    Bookmark   June 30, 2010 at 5:00PM
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