A "different" Kohler problem

[Alan]

I've got a 25 hp Kohler horizontal with arund 1300 hours on the clock. I haven't been running it much lately with the dry weather here and it suddenly developed a potentially severe problem.

First start of the day, the last 3 out of 4 starts it has started right up but only been running on one cylinder. It runs for 15-20 seconds and then quits.

At that point the engine will spin over very easily, as if there is no compression. It usually backfires once when it stalls, then poops and pops until it finally lights up again. As it is cranking you can hear compression starting to build up and the starter takes a load.

Finally it lights up on one cylinder again, barely able to keep turning over, and gradually smooths out and the other cylinder kicks in.

There is no odd noise during all this other than what *may* be lifter clatter while cranking. One it runs on two it shows no noticeable power loss or lack of RPM.

Keep in mind that this came on instantly, one start was normal, the next was choke & puke. I haven't checked compression yet but I have held my hand in front od the exhaust and there is virtually no air coming out of the pipe when it is cranking with no resistance.

Any ideas of where to start, other than a compression test to confirm what I already suspect?

[Dan1944]

Hydraulic lifter problem in cylinder that does fire at first.:o

Dan the lawn care man

[Dan1944]

Wht I meant to say was : Hydraulic lifter problem in cylinder that doesN'T fire at first.:D

Dan the lawn care man

[sdwally]

We have had similar problems with some of our Kohlers. With that many hours try use electrical tape and tape up the spark plug wires. If that helps replace them. Also replace the condensor. Sometimes we have also found bad coils.

[Alan]

Both coils were new this spring after the originals developed problems cutting out. I'm 99%+ sure it's losing compression somehow. You can hear a "gurgling" through the muffler when it cranks freely with no start.

Also, when the coils were acting up there was a load on the starter when it was cranking. With this new problem it sounds like it's virtually freewheeling, as if the plugs were out.

[sdwally]

Check and adjust the valve clearance. If I'm not mistaken the access plates are on top of the engine just below the intake manifold. Access plates should be about 2" X 3" with a bolt in the center.
After adusting you can spin the engine over by hand(spark plugs removed) and make sure the valves are moving. If the valves are don't need adjusting, it might be time for a valve job or new rings, if the cylinder is not worn out.
After adjusting the valves a leak down detector will let you know if it is valves or rings.