Kohler CV23S, smoke, won't start, comp. OK – what’s wrong

[Thanks_a_million]

what color is the smoke? Black/ dark or blue-grey-whitish color?

If it is black smoke, its getting too much gas, and the float needle or carburetor may be the issue - if it is blue-grey (some call it white) it's burning oil and you may have a bad breather or more likely, a blown head gasket.

I'd call it "blue-grey". I am familiar with the smoke from a rich mixture - doesn't seem to be that. What's more, it's a huge cloud compared to what I would expect from a rich mixture.

If the compression is around 115 and 113, would that be the case with a blown head gasket? How do I check for a blown gasket?

Also, how do I check the breather to see if it's ok?

Thanks, Mark

[bgsengine]

Blown head gasket will be a break between cylinder bore and the valve lifter galley which leaks compression into the crankcase,over-pressurizing the crankcase and pushing oil through breather tube and into the air intake where it gets sucked in and burned off. Compression test will NOT detect a slightly blown head gasket - a leakdown test will, if done right, you can spot air blowing heavily out the dipstick tube , breather, etc. (There WILL be some leakage past the rings in the way of blow-by so just air blowing out the dipstick means nothing without a flow meter attached to the leakdown tester to determine the rate of leak down.) - The same may be said if you did a leakdown test and heard air seeming to come out the muffler area, it could be a blown head gasket behind the muffler.

Only 2 ways to verify a blown head gasket - leakdown tester (with flow meter) or pull the head and visually inspect it. (You may need to, if both valves closed and air leaking out the exhaust, you could still have a dropped valve seat)

No way to test breather to see if it is OK, and since a blown head gasket will invalidate any other tests anyhow, first you need to make sure it is NOT a blown head gasket or excessive blow-by , and then simply replace the breather. (But, if the return drain hole in breather is plugged, it may just need to be cleaned out)

[Thanks_a_million]

Blown head gasket will be a break between cylinder bore and the valve lifter galley which leaks compression into the crankcase,over-pressurizing the crankcase and pushing oil through breather tube and into the air intake where it gets sucked in and burned off. Compression test will NOT detect a slightly blown head gasket - a leakdown test will ...

Thanks for the info, very helpful.
Can you point me in the direction of info at how to conduct a leakdown test. That would be helpful.

Thanks, Mark

[Thanks_a_million]

No way to test breather to see if it is OK, and since a blown head gasket will invalidate any other tests anyhow, first you need to make sure it is NOT a blown head gasket or excessive blow-by , and then simply replace the breather. (But, if the return drain hole in breather is plugged, it may just need to be cleaned out)

On inspection I see that the breather tube actually appears to be cracked through and may be leaking air. I'll need to check it some more.

[Thanks_a_million]

Need the engine's spec number too. Several of versions of CV23 that went on the Cubs.

Thanks, Spec number is 75604.

[KE4AVB]

This might help on the leakdown test info requested.

Leak tester instruction Video
http://www.youtube.com/watch?v=jc3j4ShE-tk

[bgsengine]

This might on the leakdown test info requested.

Leak tester instruction Video
http://www.youtube.com/watch?v=jc3j4ShE-tk

Or, the one I like better - Bruce's article on PERR (the place that originally brought us all together!) - http://www.perr.com/tip15.html

[Thanks_a_million]

Thanks for the leakdown test info. Wondering if it is worth the cost/effort or if I should take the head off on the side with the lower compression.

[bgsengine]

Thanks for the leakdown test info. Wondering if it is worth the cost/effort or if I should take the head off on the side with the lower compression.

thats the easy way out , but if everything else seems OK it may be the way to go - an experienced pro can make it a judgement call, just by a process of elimination. I would be willing to bet on 3 to 1 odds that if you did, you'd find a blown head gasket - but - word of advice - make sure you have everything you need to put it back together right (Torque wrenches, service manual, feeler gauges, know the cost of gasket set / head set, or better yet have them on hand first, since if you pull the head you WILL need new gaskets anyway)

[KE4AVB]

Something got me wondering here. It was the crackling noise. Have you pull the blower housing (engine cover) to see if there is a mouse bed in it which would have caused the engine to overheat? They are bad to do this during the winter months.