engine help
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New User
Joined: Jan 2011
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engine help
Today i drove my 83 ford f250 xl 300 4.9L L6 single barrel carburetor. I drove it for about 5 to 10 mins when i got back i tried to shut it off when it started "dieseling" as ive heard its called when a engine continues to run when you shut the engine off. i popped the hood after it finally stopped and saw that the exhaust manifold was a glowin. it was a bright orange color. what could cause this im pretty sure it was low coolant. what could cause the dieseling? any help is appreciated!!
Elder User
Joined: Nov 2010
Posts: 536
Likes: 2
From: Jacksonville, NC
I'm pretty sure that a plugged/clogged catalytic converter would cause your manifold to glow red, if there's still a catalytic converter on the truck. If not, then I have no idea what else could cause it to glow red.
If I'm not mistaken, the dieseling is from pre-ignition. You might have hot spots in your combustion chamber, or maybe plugs that run too hot for your application.
If I'm not mistaken, the dieseling is from pre-ignition. You might have hot spots in your combustion chamber, or maybe plugs that run too hot for your application.
Cargo Master
Joined: Apr 2003
Posts: 2,057
Likes: 424
From: Too close to Houston
The manifold was glowing after running only 5-10 minutes? Wow.
I wish I knew more about your caburetor to tell you for sure, but the 2150's have a dashpot that holds the throttle at idle position when it's running and drops the butterflies closed when you turn the key off. That was the "anti-dieseling" fix of the era. When we had a dashpot fail we would crank the idle speed up enough to keep it idling. We'd have to kill it in gear to control dieseling until we could get the dashpot replaced.
As for the hot manifold, was the whole thing glowing or just one area? You may have a cylinder that's not firing. It's just pumping the perfect air/fuel mix into the manifold to burn there. Start the engine cold. Shut it down after about 15 seconds and then see if one of the exhaust outlets is still cold. A $30 infrared temperature gun from Harbor Freight is perfect for this but if you don't run it too long you can wet your fingertip and check the old-fashioned way.
I wish I knew more about your caburetor to tell you for sure, but the 2150's have a dashpot that holds the throttle at idle position when it's running and drops the butterflies closed when you turn the key off. That was the "anti-dieseling" fix of the era. When we had a dashpot fail we would crank the idle speed up enough to keep it idling. We'd have to kill it in gear to control dieseling until we could get the dashpot replaced.
As for the hot manifold, was the whole thing glowing or just one area? You may have a cylinder that's not firing. It's just pumping the perfect air/fuel mix into the manifold to burn there. Start the engine cold. Shut it down after about 15 seconds and then see if one of the exhaust outlets is still cold. A $30 infrared temperature gun from Harbor Freight is perfect for this but if you don't run it too long you can wet your fingertip and check the old-fashioned way.
New User
Joined: Jan 2011
Posts: 1
Likes: 0
From: Mesquite, TX
I done had the same problem with a F350 I used to own. What, with the dieseling an all that. I had turned my truck off just like any other night when I pulled up at the bar an it went *SPUT, SPUT, GRRREEECH* I'm not sure what caused the grinding sound there at the end, but I done wrecked that truck anyways the same night. I totaled it, so I never did find out hows to go about fixin her. My buddy Keith thinks putting a couple teaspoons of moonshine in the carburetor would have done her some good, but then again, my buddy Keith aint so smart. I hope I helped.
Posting Guru
Joined: Jun 2009
Posts: 1,509
Likes: 1
From: Wagener, SC
I done had the same problem with a F350 I used to own. What, with the dieseling an all that. I had turned my truck off just like any other night when I pulled up at the bar an it went *SPUT, SPUT, GRRREEECH* I'm not sure what caused the grinding sound there at the end, but I done wrecked that truck anyways the same night. I totaled it, so I never did find out hows to go about fixin her. My buddy Keith thinks putting a couple teaspoons of moonshine in the carburetor would have done her some good, but then again, my buddy Keith aint so smart. I hope I helped.
I ain't never before seen anyone post Texan colloquialism, but you nailed it! Lookin forward to reading more from you.
And watch out for Keith....
