tmajikman

Yes it can, why did you say the radiator cap was a bad choice? I would get a pressure tester and see if you can find the leak, a bad radiator cap can also make your system not pressurize, even new stuff can be bad, I would take the cap back and see if that is the problem. Put back your regular pullies too. Like Hack said, they are not worth the trouble.

Hack beat me to it again.

91stanger

OK lets see, This is straight out of the ford manual..

When the coolant is cold, the thermostat is in the closed position and the coolant flow is
restricted to the cylinder block, head, intake manifold and heater. As the temp increases, the t-stat opens allowing a portion of the coolant to pass into the radiator. The coolant flows throught the radiator tubes and is cooled by air passing over the cooling fins. Coolant is then
circulated from the radiator outlet tank through the water pump and into the cylinder block to complete the circuit.
The coolant expands as the temp and pressure rise in the system. When the limiting system working pressure is reached, the pressure relief valve in the radiator filler cap is lifted from its seat and allows coolant to flow throught the radiator filler neck and the overflow hose
into the coolant recovery resorvoir.
When the system temp and pressure drop, the coolant contracts in volume and the pressure in the radiatoris reduced. The coolant in the resorvoir bottle will then flow into the radiator through the vacuum relief in the radiator filler cap.

It sounds like to me your t-stat is stuck open , that is why it takes so long to overheat. it has to heat up all the fluid in the system . As far as the underdrive pulleys, you shouldn' t see much temp change maybe some, but not excessive. An electric fan will fix that. Good Luck.

93_five_oh

yeah i'm gonna put the old pulleys back on when they arrive. well for a minute this morning when the steam was coming out of the radiator it looked like it was coming from the cap, but earlier when i squeezed the hose i could hear a little hissing and see some antifreeze about 3 inches over on the top row of the radiator... so i'm pretty sure that's where the hole it. can i take it to a shop and get it fixed?

91stanger

Oh yeah I believe the hissing sound is the coolant going through the preesure cap into the overflow tank, normal.

93_five_oh

no no... other side of the cap. and doesn't there have to be enough pressure on the cap to let excess coolant into the overflow?

91stanger

Start with the easiest, cap and t-stat. I really doubt with all the people running underdrive pulleys your the only one with problems. Mine has em and it runs hot butI attribute that to
The h/c/i on the car.

HACKGT350

yeah you can take the car to the shop and have them replace your radiator but its easy enough to do yourself in the driveway. as for the radiator yeah you can take it to a radiator shop and have them patch it and pressure test it for you. and yes swap back your pullies they cause more headaches than you need.

91 you really didnt help any with your little story thing there. the coolant system when hot t-stat open) has a constant 14-16psi. you shouldnt hear a hiss from the over flow when the system is hot it will suck the coolant out of the over flow when you turn your car off then you will here a hiss from it because its filling the over flow and releiving pressure in the system. the one reason why they tell you to never open your rad cap when hot is because yes its under pressure but the moment you open that cap you releive all that pressure and you just decreased the boiling point so the coolant boils instantly and can seriously hurt you and yes the pullies will cause an overheating problem they spin the water pump and alt a lot slower there for causing problems because they arent running the way they were intended

1985stang

If you get a new thermostat, make sure you check it before putting it in your car. I got a new 180 degree t-stat and come to find out it was stuck open [:@]. Took it back, got my money back and bought a stock replacement. Works great

93_five_oh

thank you 91. i know how a thermostat works though. like you stated and i already said... the radiator cap won't allow coolant out until the system has enough pressure. 16 lbs.
and like i said before... it is NOT pressurizing because when the upper radiator hose is HOT there is no pressure in it. yes i squeezed it. like we agreed on, if the system won't pressurize it won't cool properly.
i'm blaming it on a leak for now... i'll pressure test it and then know. anyways, if it is a leak like i think it is, i'm getting it repaired, since it's a fluidyne radiator.

thank you all for your help!

ACE

Did you ever think of your clutch fan going bad anybody? I Had that happen on my 82 and replaced everything and still did it, changed to a electric fan and ran cold till I sold it! I doubt your underdrive pulley would really matter on your waterpump because that pulley isnt changed in diameter like the crank pulley would be correct?