engine overheating?

Question

I have a 1965 mercury comet cyclone 289,engine. It runs hot after about 20 minutes I have installed a new radiator a new water pump a new thermostat ,flushed fegine twice still no luck, radiator still has water when I check it when it cools off

Answer 1

You don't say if you replaced all of that because you felt it was already overheating, nor do you tell us exactly why you think it IS overheating --- but ---

I'll assume you went through that exercise due to an existing overheating problem. If you really ARE still running hot, you may still have an issue with air in the system that is causing circulation problems, although my old recollection of that engine layout in a '65 Mustang has me wondering where the air would be trapped.

With a cool engine, pull the radiator cap and start 'er up. Wait until the engine warms up and you should see coolant flow in the radiator as soon as the thermostat opens.

If you do see GOOD coolant flow, that's a good indication that all of the new bits and pieces are working. I'd question how hot you're really running, or consider another source for the problem entirely.

If you do NOT see good flow, either your brand new parts are failing you (unlikely, but possible) or you'll need to see if you can bleed out trapped air, and apart from raising the front of the car, my memory of the hose/radiator layout isn't good enough to guarantee a result in some other fashion. I'd check the trapped air issue before I started pulling any parts off.

Answer 2

-Are you positive the engine is actually overheating, not just a faulty sensor, sending unit, guage?
-Are the lines running into the radiator and out of the radiator both the same temp? (Both hot?) If the answer is yes, then the radiator is fine (I know you said you replaced it, but just checking.)
-The next step is to pull the thermostat, and run it without it. I've seen thermostats die right away, so be sure about that as well. (however if both lines of the radiator are hot, the thermostat is probably functioning normally)
-Did you bleed all the air out of the system? This can cause overheating problems as well.
-Are you running a proper mix (50/50) of coolant and water?
-Fan functioning properly?
-Is the radiator the correct radiator (i.e. large enough to support a small V8?)
-After that man, your guess is as good as mine. If everything's clear in the block and heads, the pump is good, the thermostat is opening, and the radiator is clear you should be cooling fine.
Hope this helps, and goodluck!

Answer 3

65' comet, sweet, was your thermostat too small? Sometimes that will make them run hot, if not, it could be you need a new oil pump, maybe it's not working to it's full potential, good luck.

Answer 4

have your heat gauge checked, it might be bad, you can also add a chemical to the radiator called water wetter that will lower the temperature about 10 degrees, summit racing or Jegs sells it, also if you don't have a fan shroud on your radiator put one on.

Answer 5

The clutch in your fan might be shot. When the engine heats up it is suppose to tighten up the clutch to make it spin faster. Ive seen it a lot on older engines.

Answer 6

Make sure your lower radiator hose is not collapsing when you give the engine some gas.

Answer 7

good car! i had a 69 merc.cyclone,390 engine .ok,it could be the heater core.is it really overheating,or does it just show it is?you could just have a bad sending unit.