Kohler 5CKM21 no compression in both cylinders

[Gjac]

Finally got to go camping last week, started the genset to heat lunch, it started right up, ran for no more than 10 mins then died. Would not start again. Checked fuel pump plenty of fuel squirted out, checked spark had spark but plug was dry. I noticed a broken wire to the fuel cut off solenoid at the bottom of carb bowl and reattached it thinking that was why the plug was dry but still no start and dry plug. Sprayed starting fluid into cylinder but not even a pop. When I returned home I checked both cylinders and neither had compression. What would cause both cylinders to have no compression? Of course my worst fear is a broken cam shaft or something serious, but I did not hear any noises when the genset died.

[Gjac]

Rigdon wrote:
if the intake valve had pressure coming out instead of in then you have stuck intake valves on both cylinders. the trick with pressurizing the cylinder through the sparkplug works very well. Other small engines used to get carbon fouling in the valve guides resulting in stuck valves and no compression usually from the carb running rich.

I pressurized both cylinders through the spark plug hole with 100 psi. At TDC air just rushed out of the intake, rotated fly wheel to different positions and compression built up no air coming out of the tail pipe or intake was noted . I went back to TDC and poured Chemtool into each spark plug hole and reinserted plugs and will soak the valves for a couple of days. At TDC I did not see chem tool leak out. May leak oy slowly. I still don't know how intake valves can just stick in both cylinders at the same time while the engine was running? I can see them sticking if it sat for a period of time without the engine running. Has anyone seen this happening before?

[Rigdon]

if the intake valve had pressure coming out instead of in then you have stuck intake valves on both cylinders. the trick with pressurizing the cylinder through the sparkplug works very well. Other small engines used to get carbon fouling in the valve guides resulting in stuck valves and no compression usually from the carb running rich.

[wa8yxm]

YOu said no compression but you said it's sucking air in the exhaust.. This is a clue. Story or two (2nd one short)
Reading Gus Wilson's Model Garage (Series in popular Mechanics) back in High School he had a car brought in with what they thought was a blown head gasket. Well he confirmed two cylinders not working and as I recall it was the intake valves. or perhaps I'm mixing the two stories it was the intake)
He screwed a spark plug housing with the plug broke out and a air chuck brazed in into the spark plug hole and put compressed air to it and noted where it came out(I am confused it was a blown head gasket, Radiator bubbled)

My car it was the intake valves (That's how the mechanic figured it out)

Sounds like the exhaust valve on yours based on the sucking (the power stroke)

[Gjac]

bgum wrote:
Try disconnecting the wire and start.

If you are talking about the wire to the fuel shut off(anti dieseling solenoid) I have done that. Also removed the fuel shut off solenoid to see if the plunger comes down when the starter button is pushed and it does.

[bgum]

Try disconnecting the wire and start.

[Gjac]

I am not sure how this is related I thought it was just coincidence at first and it maybe, however as I stated in the OP the 12v supply wire to the fuel shut off broke and the plunger would stop the flow of fuel to the engine and the engine just shut off, no fuel to the cylinders and engine of course would not start. It just seems strange to me the problem started when this wire broke. After reconnecting the wire and verifying the solenoid was good the no compression and fuel coming out of the intake and exhaust sucking in instead of blowing out occurred. Is this just coincidence or is there something I am not seeing? Does anyone know if this genset has an electronic decompressor?

[Gjac]

Muffler is not plugged because I can feel my hand being sucked in at the tail pipe instead of air coming out. It is like the engine is turning over backwards. I have heard of small engines doing this like in a lawn mower when it stops suddenly like when it hits something. Does anyone know which way the fly wheel should turn?

[enblethen]

This one?
m-20
That should have been "plugged" exhaust.
Can you get muffler off?

[Gjac]

enblethen wrote:
It could be a pulled exhaust, rare!Our other discussion came up with CH20 engine, correct?
Kohler gaskets

No it is a Command M-20EP. Very hard to find info on this engine. What is a pulled exhaust?

[enblethen]

It could be a pulled exhaust, rare!Our other discussion came up with CH20 engine, correct?
Kohler gaskets

[Gjac]

Removed all the shroud's around the genset on Sat to see what I could get too. Framing and spare tire had to come out also. After extensive research and multiple calls to people that work on small engines and gensets no one would work on one in an RV. I did not pull head because I could not find a head gasket or internal parks for this 25 year old genset they all say discontinued. Still waiting to hear from the Kohler rep he was not working Fri and Sat. Thought maybe I could get to an access cover to check cam shaft but could not. Someone suggested maybe the internals of the muffler collapsed clogging the muffler, found no rattling inside and when I cranked engine over the exhaust sucked my hand in instead of blowing it out. Also air and gas are coming out of intake instead of sucking in. Almost like in was running backwards.

[enblethen]

I wish we would get some rain!

[Gjac]

enblethen wrote:
I found a couple other manuals. They show overhead push rod type engine with gear driven camshaft off crankshaft.
I would pull easy to get to valve cover. Check to see if the valve rockers move.

Yes I know that would be the next step, it was raining all day yesterday and this morning I had a root canal done so hopefully get to it tomorrow.

[enblethen]

I found a couple other manuals. They show overhead push rod type engine with gear driven camshaft off crankshaft.
I would pull easy to get to valve cover. Check to see if the valve rockers move.

[Gjac]

allbrandauto wrote:
how do you know the compression gauge is good when you crank it over with the plus in it does it sound like its cranking realy fast take a plug out and put your finger in the spark plug port and bump it over than you will know

What I did is check the compression on my lawn mower and got 65 psi so I know the gauge is good. Yes is spins really fast and can feel a slight pressure when I put my finger over the spark plug hole. In addition when I remove the air cleaner I feel no suction on the intake, instead it blows air out of the intake.