I have a '77 ford f150 400 4 speed. My problem is at idle the engine runs a normal temperature. When I drive it, the gauge climbs to hot. If I let off the gas and push in the clutch the gauge returns to normal range. I believe it is getting hot based on how it runs when the gauge climbs and it starts hard after I drive it. If I let it sit of 15 to 20 minutes after driving, it starts fine. I have replaced the thermostat twice, going to a cooler 180 degree thermostat the second time. I checked the coolant and there is no loss. The radiator seems to be holding pressure but I replaced the cap just to eliminate it. All of that with no improvement. Any suggestions would be appreciated.

 

Are the tubes in the radiator plugged? Also have you checked the timing? Just a couple of suggestions...............

 

And make sure coolant is circulating and the lower hose has a spring inside.

 

You may or may not even have a problem if you're basing your readings from the factory gauge.

The original gauge does a better job of telling the outside ambient temps than it does engine heat.

An aftermarket gauge is your best bet to determine whether you actually have a problem. At the least an infrared temp gun aimed at the t-stat housing and lower radiator.

Josh

 

X2 on making sure the coolant is circulating, start it with the cap off and let I warm up. You'll know if it is or not.

 

All
Thanks for the advice. I checked for a spring in the lower hose and it has one. I checked for flow and it is flowing although I've seen alot faster than I am getting. The timing is ok, I think. I'm had to guess where it should be and it's there. I'm going to try an aftermarket gauge as suggested to make sure I actually have an issue. If it appears that I do, I'll start with flushing the system and go from there. One thing this truck does not have is a shroud over the fan. Could that be a cause of my problem?

 

Shroud should help cooling because the fan will pull more air through the radiator.

 

My experience has been that at road speed or moving at all you really don't need a fan. I ran my flathead 52 merc without a fan for several years.......just learned to judge my stops and not get caught in traffic. I looked at it as a game.

 

if it's overheating while sitting, you don't have enough airflow being pulled through the cores (meaning either your electric fan isn't big enough, or your mechanical fan needs a shroud, or your mechanical clutch fan clutch is shot).

If it overheats while driving, either you don't have enough surface area, you have a blockage or air pockets. It can also be that your timing or advance is not correct, or that your carburetor is set too lean.

 

Sparky RnD:
Where should the advance be set? Timing at idle is good with vac. advance hose removed.

 

I had this issue with my truck and it was the radiator, I got a new one (free with the autozone lifetime warranty) and now it seems to run too cool most of the time. LOL

 

a lot depends on how your motor is set up, where you live, what plugs you run, and more. I put mine at around 10-12 degrees with a regular distributor, and around 12-14 with an hei style. My advance usually goes around another 10-20 which depends on the truck.

 

Hey everyone I ran into the same problem with my 1977 Ford F100 Custom Its got a 302 I had overheating issues so I looked at all the threads on this website and did everything that I could think of and still didint fix it but it did not over heat as fast till yesterday I figured it out and this is what I did.

I was gonna get the old radiator roded out but the shop just laughed at me and said it was in horrible shape so I replaced the radiator and it still over heated. I bought the most expensive and biggest one I could find its a good ideas to go all out on these older trucks the radiator was a Car quest. Next was the thermostat I bought the 195 Stat Superstat Premium and a new thermostat housing because the old one was rusted out still over heated so I replaced the water pump witch was a car quest part at well so after tearing down half the engine the left passage way in the block where the coolant circulates in the pump was slightly clogged so I unclogged it and flushed the engine like a mad man it was a nightmare to see what came out. Then I installed the new water pump and put it all back together only to find it it still overheated. At this point I was scratchingy head. I got a new radiator new water pump new thermostat the upper radiator hose is new the lower one is good the heater hoses are new I had to replace those to but it still would over heat. I forgot to put the shroud back on lol then it would run for like 30 minutes so I thought I fixed it but no it still was over heating so I figured the engine was clogged somewhere so I started the engine heated It up to operating temperature and shut her down I loosened my temperature sensor take note don't pull it completely out lol coolant willl go everywhere loosen it until you see coolant start to slowly flow in my case air came out first and then coolant so that was my problem don't know if yall have tried this yet but you would think leaving the cap off the radiator would get all the air out but no and that was my problem there was an air pocket in the engine stupid air lol now she runs like a champ hope this helps everyone out.
Also my fan is a mechanical 5 blade its tjr stock fan it has no clutch on it and the shroud is the stock shroud and the AC works like a champ in that truck.

 

You realize this was a 6 year old thread?

 

New everything still overheats. Im gonna try your temp guage trick and who care how old a post is as long as helps others. Haters....

I