With the engine cold, open the radiator cap and check the coolant level. It should a little below the top of the radiator.

When we want to check if there's air in the cooling system, we run the car around the block a few times (to raise the temp so the thermostat opens) then shut it down and slowly and I mean slowly open the radiator cap with a couple of rags, then we start the car up and let the air pockets flow out. Once it's done bubbling, we add the neccessary water. Watch out for coolant and don't rev the motor. We've never had a problem with the cooling system using this method although I dont' know if it's the "proper way" .

Erik

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1966 Ford Mustang 2+2
Mine - Restomod in Progress

1966 Ford Mustang Coupe
Dad's - Original Unrestored

If you want to look at the water flow then remove the cap while the engine is cold, then crank it up and let it idle for sevral minutes, it will come up to temperature. There is no reason to drive the car to heat it up.

The pressure on the cap has no effect on how hot the car runs, just how hot it can run before it boils over. If your car is running hot in the staging lanes you need more air flow across the radiator. If you are running a electric fan you need one with more CFM's. If it is a belt driven fan, then get a high CFM electric fan and free up some HP.

quote:

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Originally posted by RonnieT:
Removing the radiator cap on a hot engine is very dangerous, even with the rags the pressure released can spray hot water out and cause some serious burns. I have seen this happen before, and have had a cap blow off on me, Burns on the stomach and chest are no fun!!!

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Absolutely! I've been severly burned twice by cars. The first time was totally my fault. I had been driving in my Cougar on a very hot day and I noticed my gauge was reading low. I was puzzled so I stopped at a gas station and popped the hood. I felt the radiator and top hose and they felt cold. Like an idiot, I took the caps off {slowly} and the second it came free it blew off and rained boiling coolant all over me. I was burned on the neck, shoulders, and chest. I remember the water blisters were the size of softballs.

The second time was a freak accident. I was helping a friend break in the cam on a 383 he just dropped in a Monza. He had made a upper radiator hose spacer out of an exhaust pipe and while we were standing there it popped loose, spun around and got him in the chest {he got wet, but not burned} but it kept going and stopped right when it was pointed at my chest. Because we were in a garage, I couldn't do anything but back up and I got scalded again. I was trapped in the corner of the garage until he was able to run around the car and shut it off. Same burns on the same part of my body.

These both happened in July, a year apart from each other. It was miserable going through the hottest time of the year with burn all over me. I sure as hell have respected cooling systems and the power of steam ever since.

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'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150

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