I have a 1970 ford f100 custom, I replaced the waterpump, radiator, and thermostat but it still won't circulate the water through the system. What am I missing? Confused....


Asked by Aug 19, 2015 at 10:37 PM about the 1970 Ford F-100

Question type: Maintenance & Repair

12 Answers


Given the age of your truck try flushing out the cooling system with a chemical cleaner. You might have clogged cooling system passages. Also check that the lower radiator hose has a spring inside of it so that the hose doesn't collapse when you rev the engine. HTH. - Jim


We blew the top and bottom hoses out. If I'm right the top of the thermostat goes towards the block right?. My next move was to take everything apart and replace the hoses and waterpump.

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The flat end of the thermostat goes toward the engine. The more pointed end is the top of the thermostat and faces the hose. HTH. -Jim


If, by chance you had the engine apart, you may have the wrong head gasket set and have some cooling holes blocked.

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Could also have the wrong water pump, depending on which engine you have.


I replaced the waterpump 3 weeks ago, and it ran great until the radiator blew. Yesterday we put in the new radiator and thermostat. When we filled it up with antifreeze the top hose from the thermostat to the radiator was swollen from pressure. Then the antifreeze flowed back out the reserve and a clunking noise started after we shut off the truck.


You seem to be getting compression / pressure in your cooling system. Is there any water in the valve covers? What does the oil stick look like?


No water in the oil. I'm going to take it all apart and replace every part again. My cousin cleaned it and now there are leaks. As a joke I told him the oil held it together. Maybe it was true lol.


Check to see if you can find any way that pressure is building up in the radiator. I don't see how the water pump could be the pressure problem if it is the right pump. ( I'm sure it is) There is a small possibility that exhaust gases can get into the system but that is very rare and I don't know if that is even possible in your case. Dumb question... is this a V-8 or straight 6? A little late to be asking that!


Straight 6, 240ci, no air conditioning, 4speed.


Be sure you have the correct radiator pressure cap on. Find a cooling system pressure tester and see what the actual pressure is. Local major auto parts store may have one they can check it for you.


Ok will do thank you

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