Gas tractor run on (dieseling)

[super99]

The new to me Oliver 1655 keeps trying to run on after shutting it off, I pull the choke to flood it. I'm wondering if the timing could be off a little causing this? I haven't worked it hard yet, this is just from running it a half an hour or longer with no load, temperature guage reads in normal range.

 

[Dieseltech]

What is the low idle speed? If too high that will cause run on.

 

[Janicholson]

The new to me Oliver 1655 keeps trying to run on after shutting it off, I pull the choke to flood it. I'm wondering if the timing could be off a little causing this? I haven't worked it hard yet, this is just from running it a half an hour or longer with no load, temperature guage reads in normal range.

Deiseltech has the answer. The idle speed should be set as low as it can be reliable to stay running, as well as a little lean on the idle mixture. The engine is staying rough running from hot spots in the combustion chambers igniting the fuel/air mix. Always idle it down and let it run for 30 seconds or so then shut it off. Colder sparkplugs can also help reduce hot spots. (nothing to do with them sparking) If nothing helps, When idles down as above, put it in road gear and with the brakes on, let the clutch out to stop the engine. Do not continue to choke it to stop, that adds carbon and washes cylinders from lubrication. Jim

 

[old]

The new to me Oliver 1655 keeps trying to run on after shutting it off, I pull the choke to flood it. I'm wondering if the timing could be off a little causing this? I haven't worked it hard yet, this is just from running it a half an hour or longer with no load, temperature guage reads in normal range.

Hot spots cause by carbon build up can cause that also. My S88 will try to do that if I don;t idle it down or shut the gas off and let it run out and then shut it off

 

[super99]

What is the low idle speed? If too high that will cause run on.

Operators manual calls for 800 rpm idle speed, I have it about 650 rpm.

 

[DanielW]

Hot spots are a common cause of this, but there have also been some folks talk ot the same problem on here, usually due to something awry electrically sending stray charging voltage back to the coil while the engine is shutting down. Might be worth putting a multimeter on the coil to watch voltage as you shut down.

 

[Dennis(IA)]

I would agree with everyone, but 60 years ago my Dad had a Case combine and it would diesel unless you would rev it up slightly. Worth a try.

 

[rustred]

Operators manual calls for 800 rpm idle speed, I have it about 650 rpm.

Try this . Back out the idle screw till the engine actually stops. That completely closes the throttle plate. No fuel , no running. That way you can use the throttle lever as your shut down. Idling it a few minutes also helps. Then you can experiment with the idle at a slower rpm if you don’t like the no idle with the throttle. Also make sure your timing is set to factory to help the cooling.

 

[Dieseltech]

Operators manual calls for 800 rpm idle speed, I have it about 650 rpm.

The 800 is diesel idle speed, gas is more like 425-500. No wonder it won't shut down at 800.