460 over heating problem
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Junior User
Joined: Mar 2010
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From: Boise Idaho
460 over heating problem
I have a 1984 f350 crew cab with a 460 that has problems overheating when in the summer time when it hot out side. Does anyone have any ideas on how to solve this issue. I put a 170 degree thermostat on it thinking that would help but it did not. I put a bigger fan clutch on it and it helped a little. I am thinking about removing the mechanical fan altogether and going to just an electrical fan set up to help get enough air flow through it. Would that make any difference? If so does how big of fan do I need to move enough air to cool the coolant down. As a side not there is no radiator shroud on it either which could be some of my problem but I am not sure. Does any one have any ideas to help me out so that when I cam hauling my camper I dont have to worry about over heating? Thank you
Tuned
Joined: Jul 2014
Posts: 270
Likes: 3
From: Texas
The fan shroud is a big part of cooling. Try hitting up the junk yard for a shroud before dropping the big bucks on an electric fan system. You might also flush out your radiator, heater core, check hoses for clogs, make sure your thermostat isn't backwards, and check your water to anti-freeze ratio. All of the above can affect your cooling.
Posting Guru
Joined: Sep 2011
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From: Northern Indiana USA
I agree, make sure the radiator is clog free, and that the fins aren't bent, or plugged up.
Also, just changing the 30 YO radiator cap on my 84 made a world of difference. Are you using a known accurate gauge?
Also, just changing the 30 YO radiator cap on my 84 made a world of difference. Are you using a known accurate gauge?
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Junior User
Joined: Mar 2010
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From: Boise Idaho
I bought this truck from an old farmer who has installed an aftermarket temp gauge. I am not sure if how accurate it is. How do I test how accurate that readings are? I mostly have problems have it over heating in the summer time pulling my camp trailer or hauling hay. fall, winter and spring I do not have a problem. Its only in the summer.
Laughing Gas
Joined: Apr 2013
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Overheating in traffic is typically an air flow problem, and overheating on the highway is typically a coolant flow problem.
Yes get a correct fan shroud. Make sure the fan clutch is working correctly and make sure the fan hasn't somehow been put on backwards!
Check radiator and AC condenser for dirt, bugs and debris blocking air flow.
Get yourself one of those point and shoot no contact infrared thermometers and take temp readings at the thermostat housing to verify the accuracy of the gauge. The factory gauges are notoriously inaccurate.
Of course check the coolant level, try a new radiator cap, and you should probably run the correct thermostat (195* IIRC). Too cold isn't good for performance or fuel economy (kind of an oxymoron with a 460).
Also, if you're grinding up over a big hill or mountain pass don't lug it at 40 mph in drive. Drop it into 2nd and take it at 2,700 +\- RPM. The higher RPM will flow more coolant through the radiator (coolant flow!) and turn the fan a little faster.
Yes get a correct fan shroud. Make sure the fan clutch is working correctly and make sure the fan hasn't somehow been put on backwards!
Check radiator and AC condenser for dirt, bugs and debris blocking air flow.
Get yourself one of those point and shoot no contact infrared thermometers and take temp readings at the thermostat housing to verify the accuracy of the gauge. The factory gauges are notoriously inaccurate.
Of course check the coolant level, try a new radiator cap, and you should probably run the correct thermostat (195* IIRC). Too cold isn't good for performance or fuel economy (kind of an oxymoron with a 460).
Also, if you're grinding up over a big hill or mountain pass don't lug it at 40 mph in drive. Drop it into 2nd and take it at 2,700 +\- RPM. The higher RPM will flow more coolant through the radiator (coolant flow!) and turn the fan a little faster.
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Joined: Jan 2001
Posts: 56,951
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From: Virginia
If the aftermarket gauge acts normal, you can usually trust them. I think the fan shroud missing is most of your problem. The fan is just recirculating air under the hood rather than drawing it through the radiator(and probably the A/C condensor too). You might want to take a water hose and spray the bugs and stuff off, and then put the shroud on.
P.S. Don't start to worry about the temp when towing unless it's approaching 230 degrees.
P.S. Don't start to worry about the temp when towing unless it's approaching 230 degrees.
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Laughing Gas
Joined: Nov 2013
Posts: 1,207
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From: S.E. Louisiana;so far USA
You have received a lot of good advice. If it overheats only at slow speeds it is often an air flow issue. Start by checking the fan, clutch, shroud, and belt tension. I once had a vehicle with a blown head gasket that only overheated at slow speeds. Try to verify the gauge with a known good thermometer or infrared thermometer. If you have an infrared thermometer you can check different areas of the radiator. If there is not temperature uniformity across the core there is likely some congestion inside or outside or both. If you have the radiator removed back flush the core externally to remove bugs. If the vehicle has A/C clear the condenser similarly. Things such as retarded ignition timing and congested exhaust can also cause overheating. I have a 1976 F-250 with a 460, a 3 core radiator, A/C, clutch fan, shroud, a 160F thermostat, and some oppressive summer heat (surely worse than yours). The truck has no problem with overheating. Best wishes. Stay with it until the problem is resolved. Repeated overheating can cause other problems (like blown head gaskets and warped or cracked engine parts). 
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Junior User
Joined: Mar 2010
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From: Boise Idaho
So I put a fan shroud on my 84 f350 crew cab with a 460. Went to take the family camping tonight with a fully loaded trailer. I go about 4 miles from the house and truck just died. I got it jump started and went about 50 yards down the road and it died again. I tool the battery out and had it tested and it tested fine. When I put the battery back in it started right up and I got a half mile down the road when it died again. I could not get it started so towed it home. When I got home it started right up. and I let it idle for 15 min. It never over heated and was running fine each time before it died. Does anyone have any suggestions. Each time it died I tried starting the it it acted like it did not enough juice to kick it over.
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Joined: Jan 2001
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From: Virginia
When it dies, jump out and take the aircleaner off and with a flashlight look down the throat of the carb and take your hand and push the throttle wide open. You should see two strong streams of fuel pour into the engine. If you do you have fuel, you must have a spark problem. If you don't see any fuel, you must have a fuel problem.
Once you figure out if you have a spark or a fuel problem, you can continue on from there. If you find you have a spark problem, I would change the ignition box on the fender, they are known to fail when they get hot.
If you find you have a fuel problem, I would check out the fuel system. Do you have dual tanks with electric pumps or a mechanical pump on the engine?
Did it always struggle to crank over when it was hot? That seems like a separate problem, that would not cause it to die but of course make it hard to get it going again.
Once you figure out if you have a spark or a fuel problem, you can continue on from there. If you find you have a spark problem, I would change the ignition box on the fender, they are known to fail when they get hot.
If you find you have a fuel problem, I would check out the fuel system. Do you have dual tanks with electric pumps or a mechanical pump on the engine?
Did it always struggle to crank over when it was hot? That seems like a separate problem, that would not cause it to die but of course make it hard to get it going again.
Senior User
Joined: May 2014
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From: Lake Elsinore
If your cooling system is working properly it won't overheat. My '83 crewcab has the 460 and I run it here in Las Vegas. I took it to work the other day when temps were above 115 degrees and it did not overheat at all. Do the easy/free stuff first like coolant level, radiator cap, fix leaks. Low coolant and bad cap will nullify any other efforts you make. Franklin is also right on about the dying issue. You need fuel/air/spark to run. Take one away and you're dead on the road.
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