Kohler flat head engine stuck valves

Bobfish1 · Jun 11, 2013

I have an old Kohler Electric Light Plant with a Kohler L600 engine which is a flat head 4 cyl water cooled and I am sure a couple of the valves are stuck (no compression or low compression). There is a cover which is on the side of the engine covering the valve springs but I was wondering if I could pour something in the spark plug holes and then let it sit to help the problem or do I need to pull the head (might be impossible to find gasket) and take the plate off to access the valve springs etc. Any suggestions would be great. Thanks!!!

ben there · Jun 11, 2013

i have the exact same plant...it was given to my dad back in the early 60's and hadn't been run in years...i pulled the head and shot Gumout carburater cleaner on valve stems that were stuck and tapped them down with a hard rubber mallet and turned engine over with hand crank,then repeated until valves moved freely...head gasket on mine is copper so i annealed it and reused gasket.
its a very simple engine to work on and only parts i've had trouble finding are rebuilt water pump and fuel pump.

greygoat · Jun 11, 2013

Pour something in the spark plug holes ?
Well, the valves usually stick open, so what
you pour in will maybe run out into the manifold
or exhaust, so you may have to do as "Ben There"
suggests.
I"ve got 11 Wisconsin 2 cylinder engines sitting
around here and several times a year give them a
shot of Marvel Mystery Oil, from a spray can,
through the spark plug holes. The can comes with
a skinny 6 inch long "Straw" that I can put up
against the valve stem, when the valves are open
so I"m sure that some of it will run down the
stem, then I crank them over a few times!

JD Seller · Jun 11, 2013

I never have had much luck with some type of snake oil freeing up valves that are stuck from setting long periods of time. Ones that are fuel gummed up yes, but not rust or carbon.

I would pull the head off and free them up. I have reused head gaskets on odd ball stuff before with good results. I usually clean the head and block up like you would for a new gasket. The spray both sides of the head gasket with Copper Coat spray. I hang the gasket up on a piece of wire. I put several coats on. Letting it get tacky between coats. Then install it when the last coat is dry to the touch.

I have done this on a lot of small engine gaskets. 90% of the time it works with zero problems.

You can also look at the valve seats. They may need resurfaced too. If they are rusty and pitted the motor will not run correctly until the valve and seats are at least lapped if not too bad. They will need ground if they are too bad.

John T · Jun 11, 2013

On "some" small flat head engines (best I recall but no warranty thats been years ago and no idea which engine) I was able to unstick valves by spraying PB Blaster etc down in the spark plug hole and using a long thin punch to lightly tap tap tap until they closed down (cam in right place of course).

However, if the valve faces and seats are rusted and pitted the valves may never seat/seal all that well????

I have also cleaned and re used those head gaskets and never had a problem in the event you have to do it the "right" way and remove the head so you can re seat the valves and lap them in with valve grinding compound etc.

It depends on how bad they are stuck and whether or not the faces and seats are rusted/pitted, but no harm in trying to unstick via the plug hole if possible???? and no harm in trying the old gasket if its not all pulled apart by removal ??

STILL BEST TO REMOVE HEAD AND DO IT RIGHT

John T

buickanddeere · Jun 11, 2013

Mechanical fuel pumps should be bypassed and one of those little 4-5psi electric pumps used. Wire the fuel pump power supply across an oil pressure switch.
No vapour lock, ability to prime if run dry and auto shutdown if oil pressure is lost.

old · Jun 11, 2013

I have one of those my self. When I got it the first thing I did was fill the cylinders with ATF and let it sit a day or 2. If I where you that is what IO would do and if the exhaust is up right pour some ATF down the exhaust pipe so as to get to the stems better.

Kohler flat head engine stuck valves

Bobfish1

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ben there

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greygoat

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JD Seller

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John T

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buickanddeere

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old

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