Need a radiator cap and truck runs WAY COOL

[vegaschevy]

My truck never really gets hot, it seems to run very very cool all the time.
I can drive 30 miles, get there and pop my radiator cap right off.
Is this from having to cool of a thermostat in the truck maybe? Any ideas?

Also my radiator has had a leak in it and I got my new aluminum Radiator today, maybe this is part of the cause on running cool? not building pressure properly?

What radiator cap PSI should I get? Is that the correct term? lol The radiator did not come with a radiator cap so Ill need to pick one up and wondering what to go with.

[olyeller70]

We need to know what is considered running cool. 180 has been the average for me anytime in Georgia with a 290HP/350. What temp is it running at? What engine is it? What temp thermostat are you running? I am sure we can help but we need more info to do this.

[CSGAS]

If your radiator has a big enough leak that it can't hold more than atmospheric pressure, then you do have an explanation for being able to take the cap off--there's no way to build pressure with a hole in a radiator any more than you can with a soccer ball or tire.

You should still be building temperature though. Burn your hand, make sure you can still feel heat. (I am kidding on that last one, do not try it at home or anywhere else)

[mclairmo]

I would not worry about it running too cool, unless you have low power issues, bad fuel economy or want to race your truck. Engine needs to reach a certain minimum temp for best power and economy. My big block Camaro has the opposite problem.

[cdowns]

a thermostat controls the running temp

[CSGAS]

Now there's a thunk. *thunk*

If the thermostat is stuck closed, then hot water is not even circulating into your radiator.

You could pull it and boil test it, but for the effort and price of the gasket anyway, even if the thermostat is good you'd probably feel it's worth replacing--they are cheap.

It may be something you'd want to try before the burning your hand idea.

You can also idle the engine with the cap off, see if any coolant is flowing when the engine is warm and the thermostat should be open. The radiator level will stay still if the thermostat is not opening.

Are there any other signs that your engine may be heating up or overheating while running? Do you have a gauge or just a light?

BTW, missed the Q about radiator pressure. It should be 12-15lbs for our trucks.

[vegaschevy]

Originally Posted by CSGAS

Now there's a thunk. *thunk*

If the thermostat is stuck closed, then hot water is not even circulating into your radiator.

You could pull it and boil test it, but for the effort and price of the gasket anyway, even if the thermostat is good you'd probably feel it's worth replacing--they are cheap.

It may be something you'd want to try before the burning your hand idea.

You can also idle the engine with the cap off, see if any coolant is flowing when the engine is warm and the thermostat should be open. The radiator level will stay still if the thermostat is not opening.

Are there any other signs that your engine may be heating up or overheating while running? Do you have a gauge or just a light?

BTW, missed the Q about radiator pressure. It should be 12-15lbs for our trucks.

bought a 16psi cap with the new radiator. I am pretty sure it is circulating. The engine really does not seem to get warm at all. it just must stay cool.

[chevy_mike]

I know mine was running cooler then what I thought it might and when I pulled the intake and t-stat housing off, I found the PO didn't install a t-stat. Really makes you wonder what PO are thinking when they do things... and this guy was suppose to be a GM master mechanic...