Engine quits for no reason - 1989 20HP kohler Magn

[Guest]

I have a 1989 deutz Allis 1920 garden tractor. After about 1.5 hours of mowing it will quit and I cannot restart until the next day or it completely cools down. Also If I happen to shut it off after about 45 minutes it will not restart. Do have a bad coil or what? The engine is a 20HP air cooled Kohler Magnum.

[Guest]

I would have to say its your coil ,I had the same problem with a John Deer

[Kent]

Dunno if it applies to your twin-cylinder, but it may be burned valves. I've always heard this symptom of not starting when hot related to burned valves on the single cylinder engines. When they're really hot, they don't have enough compression to start or keep running, but when they are cold they do have barely enough to start.... It may be worth doing a compression check to see how much compression you have....

[bobjack]

Hi Scooter, It could be your coil, condensor, vapor lock, or engine just too hot from restricted air intake or fins loaded with garbage causing overheating. Engine oil leaks cause dust and grass fragments to stick to any oily surface. Easiest thing is to swap parts from another tractor that has no problem. If you swap coils, make sure you use a similar coil (using a ballast resistor built in if your original coil has it built in, or vice versa). To check for a bad condensor, run it til it's good and hot and just disconnect the condensor and try to start it. You don't need a condensor to run, the condensor keeps the points from burning so quickly. With no condensor, the points may only last weeks or days instead of years. I'd consider the post about compression. I think it's a long shot, but never hurts to do a compression check just as part of a general physical includes listening to your heart. I am assuming your engine cranks over fast when hot. If it cranks slow when it's hot, that's a different story. Good Luck bobjack

[Al]

Hi, The first thing that needs to be established is what type of problem are we dealing with. When it quits: 1: Check for spark to the plugs. 2: If no spark, unplug the connector to the engine and check for spark, If you have spark then and didn't before then you have something external grounding out the kill line to the engine. That engine has electronic igniton and will have spark unless the kill line has a ground on it. If you have no spark either way, remove the tin work and get to the ignition module and pull the kill wire off of it. Then check for spark if none, you have a bad module. If you have spark then, be sure that the kill wire to the ignition module is doesn't have a bare spot worn through and shorting out maybe when the wire gets hot and expands a little and a worn spot touches something, shorting it out and when it cools it contracts and doesn't touch any more. Moving the wire can cause a failure like this to disapear. As long as it takes for the problem to correct itself, one should be able to isolate it. 3: If you have spark after you unplug the engine, you will need to get a diagram and work backwards in the wiring. I just had a 1920 last week with a similar problem except that it might run an hour and die, only when mowing and then in about a minute or 2 the circuit breaker would click shiut and it might only run for 3 or 4 minutes and die. The problem turned out to be the igniiton switch. It had a build up of rust on the b+ terminal and when the electric clutch was on and this rust build up would conduct to the switch housing and the current there plus the mower clutch would cause the circuit breaker to open, in a couple of minutes it would close and it would start again. This "rust" strip would get very hot and it was surprising how much current it would conduct. 4: If you have spark when it dies yell,and we will address how to trouble shoot for a fuel or other problems. The thing that needs to be done is a systematic check to divide things up and identify and isolate the problem. Remember you need 3 things for an engine to run: Fuel, compression and spark. Any of the 3 can cause the problem. We need to find out what. Take a look at it and we'll go from there. Good luck, Al

[Guest]

Here's another thing to try. My 6 hp Simplicity did the same thing last spring. I tried all of the suggestions that didn't require buying new equipment or tearing the engine down. I was also advised that I should use higher octane gas. What fixed my engine was rebuilding the carb. I rebuilt it the summer before and probably didn't need to rebuild it again just clean it. I'm now having the same problem this spring and plan to clean the thing again. By the way I gave up and bought a new tractor and will give the simplicity until July to sell if not I guess it's off to the local lawn mower scrap heap.

[Al]

Hi, One other easy thing to check is to loosen the fuel cap, and see if it helps. If the vent is plugged you could see these quitting symptoms. Good luck, AL