hydro-lock in a Kohler

[Hammermechanicman]

First check the oil level and that it does not smell like gasoline.
Disconnect the sparkplug wire, strap down the the engine brake bail at the handle. Turn mower on side and try to turn engine with the blade. Can't turn? Turns gritty? Turns smooth?

 

[Bertrrr]

Don't give up on this forum there are a lot of smart guys here and give good advise, you're problem is unique in that it does not add up logically but Lots of times this happens, my mind set is to keep an open mind when trouble shooting a problem. ( like you installed a new plug but the new one is bad ) you just never know.

 

[kjonxx]

Valves are out of adjustment.

 

[hlw49]

Looks like it has a compression release due to parts break down. Take the valve cover off spark plug out and turn the engine over by hand. Watch the valves and see if the bottom valve bumps open just before TDC. If not it has a bad compression release.

 

[STEVES]

Didn't listen the first time to check & watch valve movement. Hummmm... common sense??

 

[crazy charlie]

But, as I said, I was able to get it to run, and it ran smoothly for 15 minutes. You'd think a mechanical failure wouldn't come and go, and specifically go away when I pull the spark plug. Tried that several times. Spark plug in, CAN'T pull cord. Spark plug out, CAN pull cord.

I had same exact on my LT1000 tractor mower with Kohler. My small engine guy replaced the carb and problem solved.
He said the carb was dripping and causing hydrolock and he was correct.Signs leading up to this were longer than usual cranking to start it AND excessive smoking for approx 45 seconds after initial start.All better now with new carb.Charlie

 

[mynova63]

I have a Lawnboy 10730, with a Kohler XT650 engine. Five years old. Seems to have developed hydro-lock, whereby I can't pull the starting cord. I remove the spark plug, and I can pull the cord fine fine (though nothing comes out of the plug hole - I would have expected some oil to shoot out). I replace the spark plug, and I can't pull the cord again. What's the fix???

This engine has a compression release built into the camshaft. Sounds like its not working, possible broken spring.

 

[MyBillyC]

Defective crankcase breather, maybe. Hydrolock may be occurring on the downstroke of the piston due to high crankcase pressure. Overfilled oil? Does the crank move at all or does it act like it's seized? Compression test, maybe?

 

[DinosaurMike]

Charlie, I once had hydro lock on my Troy-Bilt tractor from gasoline. I could not get the seat for the needle valve out to replace it so just installed a valve between the gas tank and carb. Have not had a problem since and the engine does not seem to use more gasoline than it did before.
The Kohler website pictures of the XT650 appear to show a fuel hose from the tank to the carb. There might be a way to install a valve in it to verify that it is not a leaking needle valve. Although I would think that unlikely since the OP said he was unable to restart the engine after it ran for 15 minutes.
Is it even worth fixing with an internal issue like crank bearings, etc?

 

[TobyU]

First, check the oil level and make sure it's not too low or way over the full mark. Also smell the dipstick to make sure it doesn't smell like gas and that the oil is not thinned out from fuel dilution.
Now, take the three bolts off and remove the shroud from the top so you can actually see the engine brake to make sure it is fully disengaging when you squeeze the safety stop bail on the top handle.
I get a number of mowers in a year where people say they can't pull the rope or it's hard to pull and it's simply because either their cable has broken, the plastic holder come out of the handle, or something has stretched or bent so it is not disengaging the blade stop.
While it is possible to start most of these engines once they've been used a couple of years with the friction break against the flywheel, it makes it much harder to pull to get to that point of starting.
Yours is a little different because the XT series has a wire in the graphite shoe or whatever it is and that's what the kill switch is also but often that fails and these things will sit there with the handle released and the blade break grinding on the flywheel for 10 or 20 seconds if not longer because it's not making enough electrical connection to actually shut off the ignition.
Regardless, take that shroud off which is very simple with the 3 10 mm nuts unless of course one of the studs to try to tries to come out with a nut which happens about 15% of the time but you should be able to get the shout off.
Then remove the spark plug wire just for safety, and then squeeze the top handle or tie it somehow so it's in the start mode.
At this point make sure you can spend the flywheel easily by hand.
I had one just come in last month that said it was locked up and you couldn't pull it and it was actually the drive belt had slipped up above the pulley and was wedged into the bottom of the engine and it was darn near impossible to pull.
If this is fine, put it back together and you probably are looking at a compression release or valve adjustment issue.
I will say this is not a common problem as the XT's do not have a high rate of problems with compression release problems or valves being out of adjustment but both of those will certainly give those symptoms.