The Stovebolt Site Forums The Shop Area Engine Shop Radiator Overflow Question

1948 Chevrolet 1/2 Ton with 235ci engine. Today was a great day, I ran the engine for a good 10 minutes straight, this is after the last 1 1/2 years of doing a restoration on it. I was in a hurry when I filled the radiator (it's an original Harrison in real good shape) and I only put 1 jug (4 quarts) of Antifreeze and then I filled the rest up to the top of the radiator cap with water from my garden hose. I know I should have measured and used more Antifreeze, but i was in a hurry. In any case, after running the engine around 6-7 minutes of getting hot, it started to gush out the coolant water mix, down out of the - overflow tube, gushing pretty aggressively down the tube. QUESTION: Is this happening b/c it's boiling up inside (needed more antifreeze to water ratio) or because I put too much volume of fluid in the radiator, or could it be due to both?

Also, I ran a heat meter on the engine area when I was testing. The Head on the Starboard (distributor) side was 154 degrees, the Head on the Port side was 160+ degrees, the Thermostat housing was 147 degrees, the Engine Block in various areas ranged from 135 to 150 (the Port or Exhaust side of the block being the hotter side.) Are these numbers within specifications?

Water and antifreeze boil at about the same temp., a good guideline is to add a 50/50 mix., use distilled water if your local water has high salt content.

Modern overflow tanks, while not original, catch all the overflow water. There is a good vertical one one on some Dodge trucks that fit well on early trucks.

Ed

You probably trapped some air in the engine block and the overflow was caused by air expansion, not boiling. I like to do an initial fill with the thermostat removed, and allow any trapped air to purge out until the coolant level stabilizes at the thermostat housing- - - -then button everything up and top it off as the engine warms up. Your numbers look good- - - -nowhere near hot enough to boil anything, water or antifreeze.
Jerry

My 216 did something similar. Once the fluid level dropped to just above the fins, it stopped and stays at that level. Do you have a zero pressure radiator cap on it or is the old one plugged up causing a pressure build up?

Chris

You likely overfilled your radiator. Look at the top of your overflow tube. Anything above that level will end up on the floor/ground. Fluid expands when it heats so just below the tube will become above the tube and ejected when hot. My experience is the same as Chris'. Just above the fins cold is where my '38 stays. When evaporation drops it below the top of the fins I put a 50/50 mix in to about an inch above.

My sincere thanks!