What pressure radiator cap and what thermostat should I be using for my car? It's a '66 289 with a new three row radiator, five blade fan and coolant recovery tank. I've added a bottle of Water Wetter, but the engine still gets very hot at idle. It does fine when moving. I have a stainless recovery tank and it has an overflow tube. Coolant will vent out of the tube as the engine heats up. When I'm sitting at a traffic light the gauge keeps climbing past the half way mark. What can I do to cool this engine down?

 

I'm not sure what pressure my radiator cap is, but I am pretty sure that I have a 180 degree thermostat. I was having overheating issues with my 65' 289 and I tried everything I could think of before I broke down and replaced my radiator. I went with a new aluminum one from Summit. It was a direct replacement and dropped right in with now problems at all. I think I paid less than $200 for it. I also added Water Wetter when I installed it. Now I don't have any issues with overheating. I run right around 180 degrees even in the FL heat and traffic. Even with the A/C running.

 

There are several things you can do. First you need to determine the actual temperature. Hook up a cheap temp gage and see what the actual temperature is. That would determine if you are actually running hot as 220 is considered hot. If you are filling your radiator to the top, as the fluid heats up it will expand and will cause it to fill your reservoir.

I use a 180 degree thermostat in mine, and I actually drilled three small holes in the side which will allow a slower heat up of your fluid. If you are not running a shroud, just adding a shroud will help, the distance between your fan blade and the radiator will make a difference and if all else fails an electric fan with a CFM around 2500 should help solve your problem.

 

13 lb cap is what I run with 180Tstat

You need a fan shroud if you don't have one...adding will solve your problem.

If you do have a shroud then get your hands on an IR non contact temp gun....measure the top of the rad near the top hose and Tstat housing (This number equals engine temp)
Then measure the bottom hose at the base of the radiator (this number must be cooler than top hose temp by a good amount I'm guessing at least 20 deg cooler...this number equals the effectiveness of the cooling system as this is water used to cool the engine)

-Gun

 

The cap should be a 13lb unit.

The factory thermostat is a 192/195 unit. I run a high-flow 195 and it works great. Remember, the thermostat regulates minimum engine temp, not maximum. These engines are designed to run at 195-210* for optimal efficiency.

I agree with fordoldies, you need to figure out how hot 'hot' is. The stock gauge is notoriously inaccurate. Even taping a thermometer to the radiator will give you a decent idea how hot things are getting.

 

Is the radiator fan shroud installed? If it isn't, this can greatly reduce the amount of air flowing through the radiator and cause the coolant temperatures to increase. A 180 deg. thermostat is fine. Is it the original fan, (they draw the most air through the radiator), or an aftermarket clutch fan or electric fan? If it's an aftermarket fan, try reinstalling the O.E. fan and you may find the engine running cooler.

What temperature is the coolant at when you are experiencing problems?

 

13lb cap and a 195. Do you have a fan shroud?

 

The car does have a fan shroud and O.E. five blade fan. I haven't pulled the thermostat so I don't know what deg. it is. I guess my first step is to get a temperature reading of the coolant and go from there. Thanks to everyone for their inputs.

 

not sure where you live but using 50/50 versus 80/20 made a big difference for me in operating temp for me....

would placing a thermostat in the overflow water accurately get the temperature?

 

No. You need to tape it to the top tank.