Hey guys, I have rad thru the topics to try and find a probelm like the one i have no luck. 1977 f-250, 460, automatic, factory air (134a). Been going to Lake Havasu for over 12 yrs. Last year the truck started to run hot so i started to try fix the p[robelm before this years trip. repaled the rad with a 4 core, got rid of the fan clutch, used a fan clutch eliminator kit,(now runs full time), new water pump and a thermostat (180 degree). but this puppy will still overheat. In the desert the needle goes past the middle when i climb hills it goes to the L on the NORMAL guage. If i leave it idling will climb to the L. I just dont know what to do anymore. Please if anybody can steer me into the right direction i would really appreciate it.


leo

 

Have you tested its flow? As to say drain the system, flush out the coolant with water. Then run the engine with the upper hose off, making sure you supply water into rad from which the lower hose can draw. Doing this will give you an idea if you have a blockage somewhere not allowing the coolant to flow efficiently.
Its a pain of a test......done it once. But its a fair test.

Also, could double check your thermostat. Sometimes, new things just come in the box already bad. Happens.

 

Have you checked the engine timing? I had a 460 that the timing was retarded and it caused the engine to run hot. Also, how many miles on this engine? Timing chain and gears been replaced?

John

 

hey peppy, i have gone thru 2 thermostat's since last year same results. I may have to try the flow test, but i can see in the top of the rad that the flow is very good. hey jt merret, the engine has about 130,000 on it but the timing chain and gears where replaced at about 95,000 miles, also i redid the heads with d0ve heads earlier this year i had a burnt valve. Everything looked really good under the heads and manifold. still holds really good oil pressure.
One more question? Do you guys think that the ported vaccum switches could cause this problem?

leo v

 

This is a long shot, but I've seen it happen. If the engine ever got really hot, you might need to replace the sending unit. They will often go bad after getting overheated. Good luck.

 

holland501 makes a good point. Have you ever installed a mechanical gauge just to see what readings you get? A bad sending unit can give high readings. Also, on a Ford there is what they call an Instrument Voltage Regulator (IVR) that is mounted on the back of the instrument cluster that regulates the voltage to the gauges at around 5 volts. If the IVR goes bad it can also cause gauge problems. Do all of your gauges seem to read high?

John

 

Hey jr, Well the amp meter doesn't work, fuel gauges is just a little shy of full when the tanks are full, iol pressure seems to be about right and the temp gauge reads about between E\M when driving around here in the Los Angeles area. Had a thermometer put in the rad when it was flowing and it reads 180 solid no movement, when the gauge reads E\M. Does it matter which heater hose goes in what direction to the heater core? The heater works great and it will come down in temp when i turn it on high when running hot.

thank you
leov5

 

I have a couple suggestions...

Do you have a shroud? - it makes a big difference when parked and in traffic. The fan blades should be half in and half out of the shroud. It's been said in the past that a good working clutch fan will cool much better than a solid or flex fan... But I have no personal experience there.

Between the top of the grill shell and radiator support, there should be two pieces of rubber - these are often missing. They are designed to force air to go through the radiator instead of the easier route over the radiator support. Mine were missing so I made larger ones to seal this all off and noticed a difference in operating temp.

Also check the timing - either too high or low will cause heating.

Marty

 

Flow through the heater core shouldn't have any effect on engine temperature but the fact that by running through the heater and dissipating heat by using the high blower indicates a definite cooling problem. Are you sure that the big spring that sits in the lower radiator hose is in place so the hose can't collapse? I have seen where the spring was left out and under high water pump demand the hose collapses and restricts flow. The shroud suggestion is definitely one you should look at. How about the air intake for the carburetor? Is there a tube connected to the air cleaner that draws unheated air from the front of the grill or is the air drawn from in the engine compartment? Have you made sure that the condensor is clean and free of road grime and bugs/dirt. Even though you have a new radiator if the condensor is dirty enough to restrict air flow that will definitely cause cooling problems. Again, check the engine timing. I would clean the A/C condensor, radiator and any other coolers located in front of the engine with some coil cleaner available at any A/C or appliance repair parts place. Do you have an engine oil cooler? Truck didn't come with one originally and the thinking is it should be able to cool adequately without one, but if you plumb in an auxiliary oil cooler it will definitely help to reduce engine heat and the load on the radiator. Also, what about a separate transmission cooler? One final thought is that maybe the engine is old enough that scale has deposited inside the water jackets such that they prevent good heat transfer to the water.

John