I have a 78 F150 that I replaced in 2002 when I bent a rod. I took the old motor to NAPA and traded for a rebuilt. After many upgrades to the motor it has cooling problems and overheats every time I drive it.
Even though I replaced the motor in 2002 I hadnt really driven it muchuntil last year. The motor was broken in properly and I am running Mobile 10w 30 in it now with a can of MOA.
Some more info: The other day the truck stalled because it got hot outside and the water guage read 200degrees+. I had some time on the side of the road so I took the carb apart and found that the gas had boiled out of the fuel bowls. The electric fuel pump is new and the filter is also. I am confused why the fuel would get so hot to boil away though.
The headers I have are not wrapped with any heat tapeand get VERY hot when running the motor. The radiator is new from the same time as the rebuilt motor but I did reuse the water pump with stock 18in fan with clutch.
What can anyone suggest to help me to cool this motor down to avoid any further problems?

 

Do the fuel lines get close to the headers at any point? Also, I can't remember if a 400 should have a valley pan or not.

 

Do you still have your fan shroud on?

 

Check and replace your thermostat, it should be a 180 degree. If the problem persists check the coolant pressure to make sure there are no leaks. That should get you started. Let us know what you find.

 

There is a certain T-Stat for the M-block. I believe there is also a restrictor in the block just below the T-Stat,if that is not there then it will run hot. Most rebuilders take them out and dont replace them.

 

Yes, the fuel Lines do come close to the headers. I ran the fuel line down the inside of the fuel rail and where the firewall begins. I bent the fuel line up and ran it behind the motor. I also used the heat sheilding wrap specific for fuel lines and spark plugs to try to reflect some of that heat away.

 

mine overheated this last weekend but it has a pin hole in the top of it and i think its got a small hole in the fins somewhere. could that have caused it to over heat on me. mind you i was off road and on a 4wheeler trail going up a mountain at the time so it was working kinda harder than normal. but it does run hot when going up and down the interstate and all. if that restictor is not there can it be easily replaced?

 

Yes, the M-block engines use their own thermostats; read through this:

https://www.ford-trucks.com/forums/8...ermostats.html


As for the boiling gas, these engines have an exhaust crossover in the intake manifold, not the coolant crossover that many other V8s have.

This allows the carb to warm up quickly in cold weather.

I installed an Edelbrock wooden spacer below the carb (Edelbrock 8725 - Edelbrock Carburetor Spacers - Overview - SummitRacing.com) you might look into doing something similar.

 

Yes, i do still have a fan shroud on the radiator.

 

No leaks in the coolant system, the thermostat in the truck is a 180degree one but it was from napa. I will look into finding the ford spec one and see if i have the restrictor plate, I didnt know there was one so wouldnt know if it was missing or not.
Thanks for all the help.

 

Alo, I do have an aftermarket Edelbrock manifold installed with a Edelbrock 650 carb. This setup blocks off the exhaust crossover on the stock heads. When first installed I used the stock reccomended valley pan but was having oil leak problems so I changed it out for the reccomended edelbrock gaskets. This fixed the oil leaks but the carb now gets warm quicker than with the valley pan. So it was good and bad to make the swap.

 

I contacted the local FORD dealer to track down the thermostat from motorcraft, closest one is located in Kansas. Sounds like it is suppose to operate at 192 degrees from what the spec book said at the dealer. I ordered it ground so once it arrives ill make the swap and post the results.

Has anyone wrapped their headers and seen heat reduction under the hood?

 

i put steel wool in the passage it will quickly clog with carbon and no long let heat through

 

rmodel65
In response to your post, which passage did you put the steel wool in? The exhaust crossover from the heads that runs through the stock intake manifold?

 

yes through the passage in the heads the wool will get covered in exhaust fumes till it clogs which doesnt take long