The Stovebolt Site Forums The Shop Area General Truck Talk radiator overflow problem

hey guys i havent found my answer on the topic forum so my problem is i have a 49 pickup which i have had for years all original except motor which is a 235 62 chevy motor,it has always seemed to have antifreeze loss thru the radiator overflow tube,i have changed all hoses new radiator,new water pump,several thermostats,new heater hoses,fresh antifreeze and it will still lose water whether summer or winter especially just sitting there idling and i have lowered the level in the radiator it still wants to come out the overflow tube i have given up until i met this web site can you give me a clue josie

How's the temp? If it's not overheating could be the rad cap needs to be replaced might not be seating against the rad inside lip where the rubber seals against the rad what pound rad cap are you running?Check to make sure your cap is sealing against the rad.lip inside the rad.


Pete

Josie, if you keep adding coolant you’re going to keep boiling it out. The level in a stock AD radiator when "cold" should be just barley above the baffle in the radiator. This is often mistaken as a low coolant level, if you add coolant to bring it up some it's just gonna puke it out. As Pete stated, if your temperature is running normal then let it seek it's own level, put the cap on and forget it. If the cooing system is stock then it is a zero pressure system, you can get away with a 4lb. cap but no more or you will be bending tubes in the radiator and heater coil. Running your cooling system at 4lb. will increase the boiling point slightly. Your '62-235 would have originally run a 160° to 180° thermostat depending on the season.
Denny Graham
Sandwich, IL

The simple fix is to install an overflow jug.It is natural for your radiator to overflow as the coolant heats up.

I agree with Denny. I run a zero degree cap and it doesn't overflow a single drip.

I would make sure and check when the motor is idling if in fact that it is leaking out the overflow tube and not the water pump or hoses.You can do a pressure test to find out.

I would check the temperature of the upper rad hose when the gauge says it is warm. If the rad hose is cool, you have an air lock behind the thermostat and the coolant in the block will form voids and expell coolant out the overflow. This situation will not alwayys cure itself and in that case the air needs to be removed.

Check the cap if it has a "R" in the part # it is the wrong cap it is for a system with a coolant jug. It will expell coolant into the jug when when it gets up to temp and suck the coolant back into the radiator when it cools off. The coolant level should be about 2 knuckles down on your index finger(old country boy measurement).