I have a friend with a 94 F-150 that is constantly over heating. He has checked the water levels and checked for leaks. None found. He has changed the thermostat and it is still overheating. He has thought about changing the fan clutch, but isn't sure that will resolve the problem. I suggested checking the oil levels, but that is a stretch. Any ideas on what could be going on? Help!!!

 

I have the exact same truck but never had overheating problems. Personally, I would try a few things.

First, does the truck smoke? If it does, he/she may have a blown head gasket. This happened to me on a car and it overheated constantly until I figured it out. It just went and I was screwed (did this a second time from a faulty head gasket about 3 weeks later). You can check the coolant to see if there is oil mixed in and check the oil to see if it looks like mayonaise. If either one does.........ouch! You could also do a compression check too. I think and that might give you some indication as well (I could be off base on this, but I don't think so...I'd try it).

Second, it is possible that there is a lot of scale or buildup causing a blockage in the block preventing the flow of coolant. I don't really know what to recommend for this aside from flushing the system over and over. I doubt if this is the problem. Could also be scale buildup in the radiator too or too much crap in the cooling fins on the radiator not allowing much air to pass through.

Third, you could try running the truck without a thermostat for a while and see if it still overheats. It should run really cool. I think the housing will go back together without a problem. If it does overheat, probably a blockage or possibly a water pump(?) going south. The water pump should be leaking from the underside if it is bad, but it may not...I don't know for sure. I hate changing water pumps on a 302 as it is a long and frustrating job (prepare to bust some knuckles). If it doesn't overheat, I would say the fan clutch or, more than likely, a bad thermostat. My dad went through two brand new faulty thermostats on his Lincoln from the parts store before he got one that worked. I have had the fan clutch problem before. Very easy to remedy. Get one from the junk yard (much cheaper than new).

You could test the thermostate by taking it out and putting it in boiling water to see if it opens. Quick and easy. Also make sure it is installed the right way too. Pretty simple but I had a really dumb friend who forced his in the wrong way....need I say more?

Another option is to take it to the local Ford dealer and have them troubleshoot it if it is really bothersome and there are time constraints involved. It should only cost about $40-50 for them to say what is wrong and take about 1-2 hours and less if it is plainly obvious.

Personally, I'd try these suggestions and wait for others to give ideas if you have time to work on this problem.

Keep us posted as I am curious about this.

PLEASE NOTE: I have had many, many fords over the years and am only recommending what I have tried, had done and that which has worked for me.

 

The more I think about this, the more I think it is the water pump.

To test, make sure the coolant is full. Take the return hose off the radiator (the top hose) and start the engine. It should pump fluid all over the place if it is good. If it doesn't, problem solved.

Lemme know.