K301 Issues

Hi WFM folks. My neighbor has a K301 Kohler 12 HP engine that will not run. It has spark, it has fuel (plus I have sprayed in starter fluid), and it has air. All the basics. Not even a pop. I'd like to help the guy but as it is not my tractor I am being cautious...overly cautious. I know it's tough to check he compression with the ACR engines but on my JD112 I get about 70PSI on starting rotation. On his I get about zero. With his spark plug in I can rotate the crank by hand easily. When I old my thumb over the s-plug hole and rotate the crank..no pressure at all. I can see the valves moving. I haven't pulled the head as I want to make sure I have not missed something simple before I do that. I've changed out points, condenser, plug and coil. Still no pop. Again, I have spark.Did I miss anything simple or should I just go ahead now and pull the head?

I know that for the ACR models you have to spin the motor backwards to get the compression reading per the Kohler manuals. I would try this first and then if nothing, tear it apart and see what is broke.

I'd pull the head and see if the valves are sticking, especially if you don't know how long it has been since the last time the head was removed.

Travis and Ryan: The head has not been off for about 10 years as he had a major rebuild back then. The unit has been getting increasingly hard to start. On Saturday neither the owner or I could get it to even pop. I've resurrected K series engines that have sat idle for close to 2 decades with less problems. I know the ACR reduces compression at starting RPM's but does it reduce it to zero? I can spin the crank by hand with the same resistance plug in or plug out.

Stuck valve would be my guess.

I would also guess a stuck valve. I had a 212 earlier this year that did exactly the same thing. I tried everything but it wouldn't start. Pulled the head and found the exhaust valve stuck open. Freed it up and put it back together and it has been running great ever since.

Thanks to everyone. Just wanted to make sure I did not miss something silly. If it were my own tractor I am quick to be adventurous. As it is my neighbors, I am taking the conservative road for fear of making something worse than it already is. Off comes the head tomorrow night.

If no compression, pretty much has to be :
1. Stuck valve.
2. Blown head gasket.
3. Hole in piston.
4. Broken rod = no piston movement.

I just bought a 1974 112 with the K301. The previous owner thought the rod was broke. I found the exhaust valve stuck open.

Hi all...PM update. Pulled head. Was a little grease and crud on one corner of the gasket but not bad. Both intake and exhaust valves appeared to be seating but there was a lot of crud on them...especially the intake valve. Exhaust valve did show a little wear on the side closest to the piston. Cleaned everything well, installed a new head gasket, torqued in order to spec of 25-30 ft Lbs. Still can rotate crank easily by hand with plug in. Still will not even pop. I think the rings may be bad...open to any ideas.

When you had the head off did you rotate the crank to see if the piston would move up and down? If you did and there was no movement most likely a broken rod.

Hi Ryan, good travel on piston. Up and down np. Same with valves

Mike,

Try this, place the palm of your hand over the carb throat. Have an assistant crank the engine over. Do you feel suction on your hand? If not then I would say the rings are worn or stuck causing little to no compression. You may want to try filling the cylinder with ATF via the spark plug hole. Let it sit a couple of days. Drain the oil and replace with new oil. The ATF may unstick a sticky piston ring.
Could you have an obstruction in the exhaust? Can you feel puffs of air coming out of the muffler when the engine is cranked?
Make sure you have a good spark. It should be nice and blue and should be able to jump a 1/4" gap no problem. If you have an old plug laying around gap it to 1/4" and see if the spark can jump it. If not I would start investigating the ignition system.

Good luck

Hec

Thanks Hec, There is a 1.5" shaft coming off the crank, and with the sparkplug in, I can rotate this easily with one hand. I'm thinking there should be a lot more resistance. I have a spark tester and I am getting a strong current to the plug. I did swap out the Ignition coil, condenser, and points at various intervals to see if any of those were the cause of the issue. Swapping them with new or known to work components did not make a difference. I do not see any obstruction on the exhaust. It was a good idea and worth checking. I have brought many a K Series engine back to life but this one has me stifled. I'm back to the low compression being the issue.

Thanks Hec, There is a 1.5" shaft coming off the crank, and with the sparkplug in, I can rotate this easily with one hand. I'm thinking there should be a lot more resistance. I have a spark tester and I am getting a strong current to the plug. I did swap out the Ignition coil, condenser, and points at various intervals to see if any of those were the cause of the issue. Swapping them with new or known to work components did not make a difference. I do not see any obstruction on the exhaust. It was a good idea and worth checking. I have brought many a K Series engine back to life but this one has me stifled. I'm back to the low compression being the issue.

if you can spin the crank by hand you have either a stuck/maladjusted valve, or a broken rod

KB: Weird thing is that the piston is going up and down fine and the valves are as well. I don't see any noticeable gap when the valves are seated. Block and head are not breached. New head gasket. No hole in piston either. My JD112 with a K301 has 70psi compression even with ACR at starting RPMs. This K301 tractor has near zero compression.

there aren't many places for air in the cylinder to go.

valves, head gasket, spark plug hole, or around the piston thats it