Cub Cadet Model 100- 12 H.P. Over heats?

[wappler-the-cub-man]

I have a 10 HP Kohler on my Model 100. Since it was rebuilt in 2002, I have burned up 2 heads and 3 head gaskets. I usually mow 3-4 hours a week. Every time I finish, I use my air compressor to blow all the junk out before I shut it off and park it. Any ideas on why motor keeps blowing out the head gasket? When I replace head or gasket, I torque it to specs at least 3 or 4 times after running it. Any ideas would be appreciated.
Thanks for any help.

P.S. Not a 12 H.P., It is a 10 H.P.

[Matt G.]

Are you using OEM head gaskets? Is the gasket surface of the head flat?

If you are overheating, the mixture is probably too lean or the timing is off. Check the timing with a timing light or ohmmeter (gapping the points to 0.020" is not acceptable) and check the main jet on the carb. 2 1/4 turns is usually about right for the main jet.

[Merk]

What was all done to motor when it was rebuilt?

[wappler-the-cub-man]

I am assuming the 2-1/4 turns are from the closed position or counter clockwise? I did notice that I was using a lot less gas than before the rebuild.
It has plenty of power and runs good, and always starts easy.
I am using OEM gaskets and the heads were flat when first installed.
How would you use timing light on tractor? I do have a timing light
New piston, rings, valve guides, valves ground and seated, cylinder honed, and installed used carb 'cause mine had too much play on shafts.
Thanks for your help!

P.S. It's a 10 H.P. not a 12 H.P.

[eastonct124]

Do a compression test. Maybe it was decked, and the compression is alot higher than it should be.....or the cam is not timed to the crank right.
When I did alot of dragracing, we would play with the advance on the cam when we degreed it....an advanced cam by one tooth will give you tons of bottom end torque, and make the engine run even hotter than normal.
Same as advancing the timing.

[Matt G.]

I do not think a Kohler will run at all with the cam timing off one tooth. It would not start easy like he says.

Yes, that's 2 1/4 CCW after you screw it all the way in until it lightly bottoms.

You probably warped the head the first time it blew, and you keep blowing head gaskets because the head is no longer flat. You need to get a sheet of glass and some sandpaper and wet-sand the head until the gasket surface is perfectly flat again. To check the gasket surface for flatness, set it on a sheet of glass. If you can get a 0.003" feeler gauge under it anywhere, it needs to be sanded.

I still think a lean mixture is the source of your problems.

[Yosemite Sam]

I agree, check the head on a piece of glass, make sure you have a good seal between the carb and block, the timing is either off or the carb is set to lean.

Remove the grill and the points cover, crack the point screw loose and tighten it back enough that you can still move the points but not so loose that they will move by themselves. Then set down next to the right front tire with timing light in hand, hooked up and engine running (1600 to 1800 RPM) use a long thin screwdriver, reach around the front of the tractor in through the left hand side of the grill shell, put the screwdriver into the "slot" in the points and adjust the points while watching the timing marks.

Under normal circumstances, the only things that will cause a Kohler to overheat are:
Clogged cooling fins or broken fins on the flywheel.
Too high compression ratio for the grade of gas being used.
Ignition timing advanced too much.
Lean fuel mixture.
A vacuum leak at the carburetor, which will also cause a lean fuel mixture.

[Merk]

How new are your head bolts?
Old used head bolts can cause head gasket failure.
Was the top of your block check for flatness?
does your carb have a 26 in the intake side of the carb?

[wappler-the-cub-man]

Thanks for all the help. I will check out all the ideas, but first I have to get a new head, since mine is warped beyond repair. I will also get new bolts when I install the new head. I will also check block to make sure surface is flat. I can do this by laying new head on it and checking with shim stock. And where to you check timing with timing light?

[redwaycc]

just below the generator is a small hole. turn the engine over by hand and look for a "-S". clean the area off, i used a q-tip and ipa, and apply some white/silver paint. liquid paper works the best.
timing mark.jpg