Moisture in Distributor Cap
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Freshman User
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Moisture in Distributor Cap
Good Day all, I have a 78 f150 4x4 with a 302, the engine runs fine all the time as long as it is dry out or not cold. The problem i have is when it is first started, and the engine gets about half warmed up it will start to miss and wants to stall.It is not the choke sticking, i call it the Ford disease, moistue forms in the distributor cap, if i shut it off for 1 minute it will fire back up, clear itsef up and then run fine. It will do this when the temp. reaches the dew point, it rains, or in the winter if it hasn't been plugged in , if plugged in runs perfect. Any body ever have this same prob.? I have tried many different brands of dizzy caps, the vents on the caps all work. My bother has a Mustang with 302 and his does the same thing.
Elder User
Joined: Feb 2002
Posts: 987
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From: East Bend, Carolina, U.S
Spray the inside of the cap with WD-40 or a similar spray lubricant and wipe off the excess. This will not allow moisture to build up inside of the distributor cap and thus no more problems on humid or rainy days.
I've been doing this for more than twenty years and I never have the moisture problem anymore. I simply repeat the process every spring and fall just to keep an eye on it and to check the condition of the cap.
The problem you described does sound a bit like a combination of two. There are air bleed holes in carburetors that freeze over and get plugged when the air is fairly cold and the humidity is high. When that happens, the engine will begin to run rich because the fuel mix isn't getting enough air introduced through the air bleeds. This is caused by not having that warm air from the exhaust manifolds that is used on a cold start in the winter. In other words you have an open element air filter housing or the system I described is disconnected. Look and see what you have or don't have.
I've been doing this for more than twenty years and I never have the moisture problem anymore. I simply repeat the process every spring and fall just to keep an eye on it and to check the condition of the cap.
The problem you described does sound a bit like a combination of two. There are air bleed holes in carburetors that freeze over and get plugged when the air is fairly cold and the humidity is high. When that happens, the engine will begin to run rich because the fuel mix isn't getting enough air introduced through the air bleeds. This is caused by not having that warm air from the exhaust manifolds that is used on a cold start in the winter. In other words you have an open element air filter housing or the system I described is disconnected. Look and see what you have or don't have.
New User
Joined: Jan 2008
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The only problem I have ever had was when washing the engine at the car wash.
My Ford engines stay dry and I live in the most diverse climate In Canada I know.
For added protection make a trip to the junkyard and grab a rubber distributor shroud off of a Lincoln or something.
My Ford engines stay dry and I live in the most diverse climate In Canada I know.
For added protection make a trip to the junkyard and grab a rubber distributor shroud off of a Lincoln or something.
Senior User
Joined: Apr 2005
Posts: 446
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From: South Bend, IN
What you are describing are the classic symptoms of carburetor icing. If the distributor was truly wet it wouldn't dry out by itself in a minute like you describe. Check your warm air intake system from the exhaust manifold to the air intake.
Posting Legend
Joined: Sep 2001
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Originally Posted by n9lhm
What you are describing are the classic symptoms of carburetor icing. If the distributor was truly wet it wouldn't dry out by itself in a minute like you describe. Check your warm air intake system from the exhaust manifold to the air intake.
Postmaster
Joined: Jul 2003
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From: okc
Originally Posted by old timer 4x4
The problem i have is when it is first started, and the engine gets about half warmed up it will start to miss and wants to stall......... if i shut it off for 1 minute it will fire back up, clear itsef up and then run fine. It will do this when the temp. reaches the dew point, it rains, or in the winter .
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Posting Legend
Joined: Sep 2001
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The OEM system can be improved with a bigger airbox and dual snorkels. Search for "dual snorkels" here for info.
Many times the carb icing just causes a performance loss or increased fuel consumption and goes unnoticed by many drivers. Consider yourself lucky to discover this problem.
Unfortunately even warming up the engine will not eliminate the problem and you can still experience mileage decreases etc.
Many times the carb icing just causes a performance loss or increased fuel consumption and goes unnoticed by many drivers. Consider yourself lucky to discover this problem.
Unfortunately even warming up the engine will not eliminate the problem and you can still experience mileage decreases etc.
Last edited by Torque1st; May 22, 2006 at 06:18 PM.
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How come in a diverse climate that I live in that carb icing hasn't ever happend to me with my Open filter assembly that's been on since 1990.
It can be 35*C or - 30*C still no icing of the carb
Is it because my system is "One in a Million"?
It can be 35*C or - 30*C still no icing of the carb
Is it because my system is "One in a Million"?
Posting Legend
Joined: Sep 2001
Posts: 30,255
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D- You are probably one of those people that has not noticed the problem. Unfortunately you ARE experiencing it. You can't avoid physics. Getting the proper intake system on your truck will help your performance.
Check any one of a number of references to carb icing on the Internet and this chart to show when it occurs:
Translate the glide to automotive terms like downhill...
I have a chart in °C but it is too large to attach.
Check any one of a number of references to carb icing on the Internet and this chart to show when it occurs:
Translate the glide to automotive terms like downhill...
I have a chart in °C but it is too large to attach.
Last edited by Torque1st; May 22, 2006 at 06:31 PM.
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Freshman User
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Thanks all! i thought for sure it was a moisture prob. i don't have the hot air hooked up i guess its off to the wreckers to see if i can find the sheet metal shield for the exhaust manifold, thats all i have to get as i have all of the other parts, once again thanks for the help.
Cargo Master
Joined: Apr 2001
Posts: 2,364
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From: Eustis FL
Yeah, like Dennis, my Fords have seen all kinds of weather. Never any problems with carb icing. Open element or not; Factory carb or aftermarket. But yeah, if you do have that trouble, the heat riser Ford put on at the factory will definately help.
Posting Legend
Joined: Sep 2001
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You guys have it, you just don't recognize it. Physics does not change or play favorites. Most people do not have a clue until it hits them hard enuf to stall the engine. In the meantime it is hurting your fuel mileage etc. Remember Ford did not put one single part on these trucks they did not have to. It would have been much cheaper to just put an open air cleaner on them.
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18 mpg hwy 14 city
12 months a year
no matter what the weather although the truck loves it when its raining.
Honest Eric...
The carb on my truck does not ice up under any circumstances.
However,.if you wish to discuss a 76 Maverick with a 302, that ices up up Realllllll Goood !
12 months a year
no matter what the weather although the truck loves it when its raining.
Honest Eric...
The carb on my truck does not ice up under any circumstances.
However,.if you wish to discuss a 76 Maverick with a 302, that ices up up Realllllll Goood !
