I have a kohler ch25 engine on a toro zero turn .. was reading thought some posts it is like the one bear369 posted runs very rough both coils are firing.. did a compression test both cylinders have about 150 psi on them .. has a lot of crankcase pressure it will blow the cap off the oil filler tube if you loosen it.. reminds me of a diesel motor with blow by a bad head gasket .. love some help on this one..
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Export threadit does not smoke both heads and gaskets were replaced about two years ago.. it runs rough at all speedsDoes it smoke when running ? Does it idle rough or run rough at all speeds ?
Has anything been done to the machine prior to this ?
thanks for your reply..
When was the last time you disassembled and cleaned the ENTIRE fuel system?it does not smoke both heads and gaskets were replaced about two years ago.. it runs rough at all speeds
thanks for your reply..
Amen to that.When was the last time you disassembled and cleaned the ENTIRE fuel system?
How about some clean cooling fins while you are spring cleaning that little fella'.
150 psi (if accurate) is actually very good (most motors). What obviously is very abnormal by your description is the crankcase pressure. What does that motor have for crankcase venting ? Is your muffler/exhaust plugged up? are all valves moving appropriately?I have a kohler ch25 engine on a toro zero turn .. was reading thought some posts it is like the one bear369 posted runs very rough both coils are firing.. did a compression test both cylinders have about 150 psi on them .. has a lot of crankcase pressure it will blow the cap off the oil filler tube if you loosen it.. reminds me of a diesel motor with blow by a bad head gasket .. love some help on this one..
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Hello Brian,
I don't use the pull the oil fill cover/ cap to determine a small engine has an issue with excess blowby. Why? because these small engines don't have very much crankcase area displacement like vehicle engines. Aside from that, if you had excess blowby, you would not be reading 150 psi compression.
It is rare for a crankcase vent valve to go bad because they are such a simple design.
The most common issue with many small engine applications starts at the fuel tank and up into the carburetor. It may take weeks or even years, but moisture, dust and dirt collect very gradually in the fuel system by way of the fuel cap vent and fuel containers that sit around.
The most overlooked and often avoided is the fuel tank and the supply lines. The fuel tank is likely well covered/hidden on this machine and it takes work to get it out for a good washing out and drying.
Clean out the fuel system all the way to the carburetor, then pull the carburetor off for a good cleaning.
From there, verify the spark plugs are correct and properly gapped at .030 inch.
To verify both cylinders are producing power, spray a little water on each exhaust tube to see if the water quickly burns off while running. If not, you have coil issue, or the coil kill wire is bad. The top cover will have to come off and the kill wire disconnected at each coil. Then run and test again with the water to see if both sides now burn off the water quickly.
The engine will have to be choked to shut it down.
There have been a lot of mowers scrapped, parked and abandon because of a simple bad kill wire diode assembly.
Hope this information helps.
Teryl fixes all on You Tube has some good repair videos, even though he tries to be a clown with "skits" to keep it interesting, the guy knows his stuff when it comes to small engine equipment.
I don't use the pull the oil fill cover/ cap to determine a small engine has an issue with excess blowby. Why? because these small engines don't have very much crankcase area displacement like vehicle engines. Aside from that, if you had excess blowby, you would not be reading 150 psi compression.
It is rare for a crankcase vent valve to go bad because they are such a simple design.
The most common issue with many small engine applications starts at the fuel tank and up into the carburetor. It may take weeks or even years, but moisture, dust and dirt collect very gradually in the fuel system by way of the fuel cap vent and fuel containers that sit around.
The most overlooked and often avoided is the fuel tank and the supply lines. The fuel tank is likely well covered/hidden on this machine and it takes work to get it out for a good washing out and drying.
Clean out the fuel system all the way to the carburetor, then pull the carburetor off for a good cleaning.
From there, verify the spark plugs are correct and properly gapped at .030 inch.
To verify both cylinders are producing power, spray a little water on each exhaust tube to see if the water quickly burns off while running. If not, you have coil issue, or the coil kill wire is bad. The top cover will have to come off and the kill wire disconnected at each coil. Then run and test again with the water to see if both sides now burn off the water quickly.
The engine will have to be choked to shut it down.
There have been a lot of mowers scrapped, parked and abandon because of a simple bad kill wire diode assembly.
Hope this information helps.
Teryl fixes all on You Tube has some good repair videos, even though he tries to be a clown with "skits" to keep it interesting, the guy knows his stuff when it comes to small engine equipment.