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1973 Ford F-100 360 engine overheating

I am new to this forum and I need your help. I have owned this truck for about 5 years. I had a rebuilt engine put in about 4 years ago and I have had no real problems with it. About a month ago, it started getting hot and forcing coolant out where my hose was connected. I replaced the hose, still the same. I replaced the thermostat, still the same. I bought a new radiator cap, still the same. I just put in some flush that I got from Summit Racing and I let it run for about 15 minutes revving the engine a little and then I took it for a very short ride, still the same. The only place I see leaking is where it is blowing by my hose clamp. What is strange about it to me, is that it is building up a lot of high pressure. The truck has been sitting for about an hour and the radiator hose is rock hard. I have never had this problem before in any of my vehicles. Thanks!
 
Ok, I just went and checked my truck and the radiator is about 1/2 gallon low and no pressure. I'm thinking maybe the heater core is plugged?? I didn't notice any water leaking from around my water pump, but I'm going to get start it and get under my truck to see if I can see anything.
 
Well, I don't know much about water pumps, I probably haven't changed one in 20-25 years. I took a hose that is on top of my water pump and turned over my and let it run for about 20 seconds and nothing came out. My guess is I might have a dead water pump.
 

Fellro

Moderator
Staff member
At that rate it seems that you are correct, the water pump isn't pushing it. The water pump on those are pretty easy to change, they are just 4 bolts holding them on once you remove all the other things that attach to it.
 

Fellro

Moderator
Staff member
On that note, the heater is the first to lose water flow when the coolant level is low. If you continue to over heat with proper fill level, feel the radiator in the center. If it is cool, you may have plugged cores. When the motor is hot and the radiator cold, it is a pretty good indicator it isn't helping to cool.
 

Fellro

Moderator
Staff member
That is a lot less likely an issue then if the radiator is that new. With the pressure build up and retention, you don't seem to have a leak at least.
 
No, definitely no leak. I've owned several vehicles new and old and I have never seen one build up that much pressure. The pump is on order, so as soon as I get it hopefully it will solve my problem. If not, and the radiator is still good, then I guess the last item is a blown head gasket.
 
Well, I finally put a new water pump on my truck and it made no difference, it's still overheating. So, I have changed the thermostat, radiator cap and water pump. I even by-passed the heater core and ran my hose straight from the pump to the engine and it's the same. It starts right up, I don't hear any strange noises. I had tried flushing the system out and it did nothing. What I have read about plugged radiators is just take the top and bottom hose off and run some water through it. As if that is supposed to unplug it.
 

Fellro

Moderator
Staff member
If it is plugged bad enough, only a radiator shop can get it to clear out. The newer aluminum radiators are such that generally they just get replaced.
 
My mistake. I was talking about the radiator on the last post, what I think might be the problem is my motor is plugged up. I only use my truck about every 3 months to go to the dump, so it doesn't get used much, also I think I put in 30wt. oil. The water seems to be getting around every where except I don't think the oil is flowing every well.
 

Fellro

Moderator
Staff member
Heater core won't cause over heat. You can simply bypass it and be fine.
 
I did, and you are right, it made no difference. I'm going to get three containers of oil with a couple of motor flushes. Flush the engine with fresh 10-30 oil a couple of times, then put in fresh oil. Hopefully, that will clean it out and it will take care of my problem. The engine starts right up and I don't see or hear any problem with the head gaskets.
 
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