Dieseling problems??
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Senior User
Joined: Dec 2010
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From: Medford, OR
Dieseling problems??
How much damage can be done if I run my truck to much without the Idle Stop Solenoid? It diesel's a little bit but I don't know if I've already caused problems or not. It's not making any funky noises so I assume she's fine. I also am not sure if that is the only cause for my dieseling problems, if anyone has any ideas shoot em past me.
Cargo Master
Joined: Apr 2003
Posts: 2,057
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From: Too close to Houston
Just kill it in gear. That will stop the dieseling. I don't think the dieseling will hurt anything except maybe your pride. I suppose it's possible to for it to kick the engine backwards before it dies, but it'll be running slow enough that it really shouldn't matter.
In the 70's I know a guy that ran his truck on weathered pipeline drip. The thing would diesel forever, it seemed. Didn't hurt the thing though.
In the 70's I know a guy that ran his truck on weathered pipeline drip. The thing would diesel forever, it seemed. Didn't hurt the thing though.
Moderator
Joined: Jan 2001
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From: Virginia
Dieseling is caused by the idle being set too high. This lets too much air into the engine when the ignition is cut off, and there are usually hot spots in the combustion chambers that keep lighting off the air/fuel mixture, even though the sparkplugs are not firing.
That's one of the jobs of the idle stop solenoid. It drops the throttle blades back when the ignition is shut off, cutting the air off to the engine so this won't happen. You will see this system more on the later vehicles with smog, because they designed the carb to be more open at idle for a leaner mixture, and the later trucks have more accessory drag so the idle has to be opened up more for the proper idle rpm. So the solenoid became necessary to stop the tendency to diesel.
That's one of the jobs of the idle stop solenoid. It drops the throttle blades back when the ignition is shut off, cutting the air off to the engine so this won't happen. You will see this system more on the later vehicles with smog, because they designed the carb to be more open at idle for a leaner mixture, and the later trucks have more accessory drag so the idle has to be opened up more for the proper idle rpm. So the solenoid became necessary to stop the tendency to diesel.
Thread Starter
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Senior User
Joined: Dec 2010
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From: Medford, OR
Thanks for the input guys, I thought I was going to kill my truck or something, I turned her off and she stayed running for at least 3 minutes, so I threw her in gear. I should be getting a new solenoid here soon to fix that problem.
Cargo Master
Joined: Oct 2005
Posts: 2,295
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From: NJ
Dieseling will crack rings and shatter pistons. It's also hard on your bearings. If the truck diesels you need more octane. Bump up to the next octane available in your area and it should go away.
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Post Fiend
Joined: Nov 2005
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From: Charles Town, W bygod Va
The solenoid has nothing to do with it. Can you turn the idle down some?
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Post Fiend
Joined: Nov 2005
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Likes: 4
From: Charles Town, W bygod Va
I think you are thinking about detonation.
Cargo Master
Joined: Oct 2005
Posts: 2,295
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From: NJ
Dieseling is essentially detonation at idle. Detonation can happen due to not just excessive timing but aso simply too much dynamic compression for the octane of fuel used. There are other contrubuting factors and things that can be done to mitigate it, but dieseling when shutting off can only be resolved by more octane, closing the throttle completely (no air) when shut off, and lower idle speed.
The best thing to do is run the octane that the engine wants, and advance your intial timing and advance rate to make hte most out of the octane the engine wants.
The best thing to do is run the octane that the engine wants, and advance your intial timing and advance rate to make hte most out of the octane the engine wants.
Thread Starter
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Senior User
Joined: Dec 2010
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From: Medford, OR
i'm using 87 and always have, i just recently got the truck timed to 6 degrees advanced like the label states, it only diesel's if its in neutral, if i put it in gear it will shut right off no problems, i did just start noticing this because i just rebuilt the carb.
Post Fiend
Joined: Nov 2005
Posts: 7,437
Likes: 4
From: Charles Town, W bygod Va
Dieseling is essentially detonation at idle. Detonation can happen due to not just excessive timing but aso simply too much dynamic compression for the octane of fuel used. There are other contrubuting factors and things that can be done to mitigate it, but dieseling when shutting off can only be resolved by more octane, closing the throttle completely (no air) when shut off, and lower idle speed.
The best thing to do is run the octane that the engine wants, and advance your intial timing and advance rate to make hte most out of the octane the engine wants.
The best thing to do is run the octane that the engine wants, and advance your intial timing and advance rate to make hte most out of the octane the engine wants.
Thread Starter
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Senior User
Joined: Dec 2010
Posts: 118
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From: Medford, OR
the idle stop solenoid is shot and wasn't doing it's served purpose for my engine, i am trying to get ahold of a new one and if i can't find a new one i'm just going to go to the junkyard and try to find one, i am not going to be able to get the part till next month.
Thread Starter
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Senior User
Joined: Dec 2010
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From: Medford, OR
she's been idling pretty high still, i havent really done to much work to the truck in the past week, how much should i adjust it, closed then 1 1/2 turns then 1/4 till it sound right?