Odd engine idle problem, looking for suggestions
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Senior User
Joined: Jun 2002
Posts: 186
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From: Tuscaloosa USA
Odd engine idle problem, looking for suggestions
Heya,
My 76 F-100 has a 360...pretty tired engine actually. Anyhoo, I keep going back and forth on whether I want to overhaul this one or buy a new one, but I digress.
Here's whats going on. I will crank it (takes a bit to get it to crank after it sits for a few days) and the idle is very high and even if I rev the motor it won't idle down, but I can turn the engine off and restart it and its at the normal, low idle speed. What can be causing this?? Basically when I want to drive it I will: 1) crank it 2) turn it off 3)immediately crank it again 4) drive...I think its possessed or something.
One other question...when I first crank it up theres little to no smoke, the engine has a good sound to it (no skips) but when I rev it up some blue smoke comes out of the passenger side tailpipe (it has straight up dual exhaust). I'm thinking about taking it to a shop to have them run whatever tests they run to see if the motor is re-buildable. I really want to go with a 390 but kind of want to keep it original so it will stay "grandad's pickup" if you know what I mean.
Thanks,
shane
My 76 F-100 has a 360...pretty tired engine actually. Anyhoo, I keep going back and forth on whether I want to overhaul this one or buy a new one, but I digress.
Here's whats going on. I will crank it (takes a bit to get it to crank after it sits for a few days) and the idle is very high and even if I rev the motor it won't idle down, but I can turn the engine off and restart it and its at the normal, low idle speed. What can be causing this?? Basically when I want to drive it I will: 1) crank it 2) turn it off 3)immediately crank it again 4) drive...I think its possessed or something.
One other question...when I first crank it up theres little to no smoke, the engine has a good sound to it (no skips) but when I rev it up some blue smoke comes out of the passenger side tailpipe (it has straight up dual exhaust). I'm thinking about taking it to a shop to have them run whatever tests they run to see if the motor is re-buildable. I really want to go with a 390 but kind of want to keep it original so it will stay "grandad's pickup" if you know what I mean.
Thanks,
shane
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Joined: Jan 2008
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Odd engine idle problem, looking for suggestions
Without getting into complete detail.
You need to check the choke and the butterfly of the carb when the engine is cold and again when it is hot.
I think the choke linkage is the problem.
That blue smoke after idle then revved is more than likely, the valve seals are toast.
[font color=red]Dennis
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You need to check the choke and the butterfly of the carb when the engine is cold and again when it is hot.
I think the choke linkage is the problem.
That blue smoke after idle then revved is more than likely, the valve seals are toast.
[font color=red]Dennis
Calgary,Alberta,Canada[/font]
[link:www.ford-trucks.com/guidelines.html|FTE Moderator]
http://www.clubfte.com/users/mil1ion/Minimorleytruck.JPG
[link:www.clubfte.com/users/mil1ion/Mil1ion.html|My Website,"North Of The 49th"]
[font color=red]
Please Don't Ask Me Any Tough Questions,
"I'm Saving My Memory For When I Develop Alzheimer's" [/font]
[font color=blue]78 F-150 429CJ,Silver,Explorer Pkg.
[/font]
Senior User
Joined: Jun 2002
Posts: 199
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Odd engine idle problem, looking for suggestions
Sounds like maybe a choke problem with the idle. Is it electric? The extended crack can very well be a fuel pump that is weak or leaking down. Best suggestion for that is to get you an electric pump from a good parts store. Not Autozone or Advance. I have done this on my 460 to solve several fuel problems and after 2 years it still works great.
As for the smoke sounds like valve seals to me. But maybe quides. Hook up a vacume gauge and see if it fluctuates. if it is steady then it is not your quides, And just for the fun run a compression test.
As for the smoke sounds like valve seals to me. But maybe quides. Hook up a vacume gauge and see if it fluctuates. if it is steady then it is not your quides, And just for the fun run a compression test.
Senior User
Joined: Apr 2001
Posts: 321
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Odd engine idle problem, looking for suggestions
Hi,
Is the smoke really blue or is it more of a black color?
If it is black it may be running too "rich".
Also, do you know if your carb. have a choke pull-off? If it does it may not be working correctly.
Post back with more info and I can try to help.
-Brents
Is the smoke really blue or is it more of a black color?
If it is black it may be running too "rich".
Also, do you know if your carb. have a choke pull-off? If it does it may not be working correctly.
Post back with more info and I can try to help.
-Brents
Thread Starter
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Senior User
Joined: Jun 2002
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From: Tuscaloosa USA
Odd engine idle problem, looking for suggestions
"Is the smoke really blue or is it more of a black color?"
--really really blue...kind of a light blue, but no black at all. The more I rev it, the more smoke comes out...looks like a fog bank if I really push the pedal down.
As far as the choke goes, I'm not really sure what kind it is. I'm not much of a mechanic, but I don't have a manual choke handle in the cab so does that mean its electric? (yes, im engine ignorant).
Again, thanks
shane
--really really blue...kind of a light blue, but no black at all. The more I rev it, the more smoke comes out...looks like a fog bank if I really push the pedal down.
As far as the choke goes, I'm not really sure what kind it is. I'm not much of a mechanic, but I don't have a manual choke handle in the cab so does that mean its electric? (yes, im engine ignorant).
Again, thanks
shane
Senior User
Joined: Jun 2002
Posts: 199
Likes: 0
Odd engine idle problem, looking for suggestions
if there are wire to the choke housing the it is electric but if there are tubes that run to the intake then it is thermal. Either one can cause problems. have the ajustment check and make sure it is not binding
Senior User
Joined: Feb 2002
Posts: 145
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From: Los Alamos, NM
Odd engine idle problem, looking for suggestions
Hey Grandad-
Welcome to FTE!
I had a '76 F-100 360, and it had a thermal choke, which means, as was pointed out, there should be 2 small tubes that run down to the passenger side exhaust manifold and goes into the choke pull-off actuator. There is also some vacuum hoses involved. Check all of the choke linkages and hoses, etc. to make sure all is o.k. and no broken hoses or bent linkages or things not hooked up or missing
Blue smoke does sound like it is vavle guides and/or valve seals. THis is a very common problem in FE engines. Have a compression check done. If compression is o.k and it doesn't leak or consume huge amounts of oil, you may just need some head work done and a good tune-up, and not a rebuild. Just a thought.
After you have some time to mess with it and get a few things sorted out, post your engine-specific questions (tuning tips, head work, rebuilds, etc) over in the FE (360/390...) forum. There are some FE geniuses over there that will easily get you lined out. Hope this helps...
Jayson
Welcome to FTE!
I had a '76 F-100 360, and it had a thermal choke, which means, as was pointed out, there should be 2 small tubes that run down to the passenger side exhaust manifold and goes into the choke pull-off actuator. There is also some vacuum hoses involved. Check all of the choke linkages and hoses, etc. to make sure all is o.k. and no broken hoses or bent linkages or things not hooked up or missing
Blue smoke does sound like it is vavle guides and/or valve seals. THis is a very common problem in FE engines. Have a compression check done. If compression is o.k and it doesn't leak or consume huge amounts of oil, you may just need some head work done and a good tune-up, and not a rebuild. Just a thought.
After you have some time to mess with it and get a few things sorted out, post your engine-specific questions (tuning tips, head work, rebuilds, etc) over in the FE (360/390...) forum. There are some FE geniuses over there that will easily get you lined out. Hope this helps...
Jayson
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From: Central Kali
Odd engine idle problem, looking for suggestions
You can make it a 390 and no one will be able to tell by looking. 
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