Dieseling Question

Spudm · Aug 2, 2016

At least this is what I think it is called.
Farmall Super A won't shut off completely when the ignition is turned off, especially if the motor is hot and has been running a while. Not sure what causes this, and how to correct it. Any info is much appreciated. Thank you.

rustred · Aug 2, 2016

yes, its called dieseling because there is ignition with out a spark. this happens because there is hot spots in the cyl. usually in carboned engines. to cure this get the idle down to 400 rpm ir less. you want the throttle plate pretty well closed so no air mixture can be sucked into the cyl's. many auto engines had an electric soleniod to close the plates once the key was turned off, thus preventing this. you just have to get the rpm as slow as you can on the tractor.

2002sliverado · Aug 2, 2016

We have a 450 Farmall on our farm that has been known to do the exact same thing. Much of the time the tractor was used as a chore/yard tractor and did not get warmed up properly under most of this use. The tractor has a lot of hours on it, so the engine is rather "tired." I am not sure if that is the case with your tractor, but in the case of our 450, it does "use" oil and I would suspect the tops of the pistons have deposits on them. These deposits, when the engine is warmed up, increase the compression ratio some and are probably hot enough to ignite the air/fuel mixture. What did help out on that old 450, was to take it out and work it some to burn off those deposits in the cylinders and on the tops of the pistons. Hooking it up to a disc or even an old plow in the fall seemed to do the trick and clean things up a bit. It really ran quite well after working it hard. Others may have other thoughts on this, but suspect I am on the right track.

old · Aug 2, 2016

As said caused by hot spots in the engine. Me to fix that I run a quart of ATF in 3 gal of gas so as the clean up carbon build up. And yes idling it down for a few minutes before shutting it off may also help

jeffcat · Aug 2, 2016

A lot of guys on here will tell you to try a bottle of Sea Foam. Full tank- one bottle. Cleans the carbon out very nicely. Also try running on Hi-test gas and not the "regular" junk. Lastly check you timing. Might be just a little off. Lastly try some copper core spark plugs if you can get them in the size you need.

gene bender · Aug 2, 2016

Just shut the engine off let the clutch out having the tranny in a gear so you push the kill bnutton and let clutch out easy to do but you should let the engine run at a lower speed o cool down. Your problem is caused by the passages in the block are plugged and the coolant cant flow past the bottom of the sleeves thus engine is running a little warm also causes a gurgling sound when warm engine is shut off.

rustred · Aug 2, 2016

i should have said also that that you you need to have the engine properly tuned up. and timing set to spec. you do not want the timing advanced or retarded too much as this is causing extra heat. you also need the proper plugs in it, not a hot plug. and work the engine hard regularly is a good idea. i remember back in 1977 our class instructor said "when i have things set to factory spec they usually run pretty dam good" the chevy's we used to pour a can of stuff in them at about 2000 rpm to clean out the carbon. water sprayed into the intake will also loosen carbon.

Spudm · Aug 2, 2016

I appreciate the replies, not sure what to try first. Thank you all!

Spudm · Aug 2, 2016

Exactly right! I wondered why it was making those sounds too....

CAROGATOR · Aug 2, 2016

Rustred is exactly right. Get the idle down. Forty some years in mechanicing and that was the one thing I learned and used the most.

guido · Aug 2, 2016

Hello Spudm,

There a few things that can couse dieseling.Here is two: A fast idle and a hot engine.

Which one do you have?

Guido.

David G · Aug 2, 2016

Idle set to high, set stop at about 400, let engine cool down for a couple of minutes at idle (600) RPM, then close throttle clear down and shut off. People always blame timing, but that has little to do with it.

ss55 · Aug 2, 2016

Some of the last gasoline tractors, built in the late 1960's and early 1970's, had a solenoid shut-off in the carburetor's idle circuit to reduce run-on and dieseling.

showcrop · Aug 2, 2016

As others have said dieseling is usually caused by hot spots in the combustion chamber from carbon deposits, from running too lean, or from retarded ignition timing, or from too high an idle. The mixture, the idle speed, and timing can be checked and hopefully one will be found to be out of adjustment and can be taken care of. Carbon deposits can be tougher to get rid of. They are usually caused by too much idling, or running too much at too low a temperature. They can also be caused by introducing too much oil whether from worn valve seals, worn rings, or adding cheap mineral oil based additives. Running gas of too high an octane will also cause carbon because it burns at a lower temperature. Regular gas should be used unless the engine knocks under a load with the timing set properly. Use of high octane gas on a low compression engine is not only a waste of money but it can damage an engine if used for too long, due to the low operating temperature. Carbon in the combustion chambers can be removed by introducing a mist of water slowly into the carb throat with a spay bottle with the engine set to a high idle.

rustyfarmall · Aug 2, 2016

Idle down the engine. Let it idle and cool down for a few minutes before shutting it off.

Spudm · Aug 2, 2016

I do idle the engine down before turning it off, perhaps not long enough though....if the engine is at running temperature, it "diesels", and I use the choke to stop the engine.

showcrop · Aug 2, 2016

(quoted from post at 13:41:25 08/02/16) I do idle the engine down before turning it off, perhaps not long enough though....if the engine is at running temperature, it "diesels", and I use the choke to stop the engine.

Have you checked the conditions mentioned above for the correct setting given in your owner's manual?

BushogPapa · Aug 2, 2016

IF it has a replacement Alternator on it and NO Diode to prevent back-feeding, the engine Will Diesel if not idling slow..

Geo-TH,In · Aug 2, 2016

Good chance you have a magneto. So when you turn it off you are just killing the spark. If you turn off the gas, it will run out of gas and die without dieseling. May take a while.

I have a Koehler and Honda that likes to diesel, sometimes in winter. Both have solenoids in carb. I removed the kill wire to ignition, turn the power, seconds later they will turn off, NEVER diesel.

Geo-TH,In · Aug 2, 2016

Not sure tractor with a letter tractor, A, has solenoid. Good change the numbered tractors may have solenoids.

pete 23 · Aug 2, 2016

No new suggestions as they have been well covered. Just wanted to share an experience I had many years ago. Was at the lake, just put the boat in and parking the car and trailer. Young fellow was cussing his car as it would not quit dieseling. I said, just put the brake on and pop it in gear and it will shut off. Was an automatic. He got all upset at me and said he just had it worked on and it should shut off without doing any of that. Well, ya, but do you want to go fishing or just sit there and cuss a dieseling engine.

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