VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 radiator overheating issue

I have a 1927 chevy 1-ton truck. I am having an overheating issue with the radiator.
First, what is the purpose of the long cylindrical tube on the right-hand side of the radiator sitting in the passenger seat?
Secondly, what is the water capacity for cooling?
Third, I feel that I may have a partially blocked radiator tubing. The symptoms are that the water flows slowly through the tubing when adding water to the radiator.
I can get about 1-1/2 gallons and it stops filling. I start the truck and the radiator level drops some due to the water pump circulating the radiator water. I add more water and it levels off.
I go for a short test run and the radiator appears to overheat and water level drops. Now this is with the engine under load. I can run the truck in a park position and it seems not to overheat.
There is no thermostat in the engine. It was removed for a full flow water system.
What is the audience suggestions to help solve the radiator overheating? Being kicked off the island is not the answer to help me.
What radiator cleaner products has anyone tried to flush a radiator that worked.
I would like to learn more about the radiator overheating before I pull the radiator and try to flush it as well.
Thanks Paul

The loss of some water when a cool engine is run is normal if too much coolant is put into the radiator. The tube on the passenger side is to drain off excess water. The coolant expands when heated so some the cold level is just over the radiator core. The expansion then fills to the top of the overflow when at operating temperature.

If there is loss when a hot engine is slowed down then the problem is likely the water pump drawing air into the coolant. Tightening the packing nut and/or turning in the grease cup a little should reduce the loss if that is the problem. It may need more packing or rebuilding if the condition continues.

To add in the direction Chip was steering you. Generally a good indicator of how much to fill our radiators so that the liquid level does not overflow when hot is the top inlet tube when cold. Every vehicle is a little different so you will have to be the judge. For one of my '29s the level is just almost to the top of that inlet tube. For another it is just covering the radiator core. The level will rise up some when hot and running. When working with the packing nut, do not over tighten it. Also do not over tighten the fan belt. It will ruin the bushings in the water pump. Many old car owners do not know there is another bushing just under the water pump pulley that requires oiling about every 50 to 100 miles.

Thank you,
I will check the packing nut to make sure that it is not overtightened.
Secondly, I was taught to press in the flat side of the water pump v belt and adjust the tension so that there is about 1/2 inch play. The goal was to press the belt midway of the flat side. Do you agree with the 1/2 inch play?
Also, can someone explain to me what is the purpose of the this round tube attached to the radiator?
Thanks

Chip,
Does this cylinder replace an overflow tube that will dump radiator fluid on the ground, preferably in to a collection pan? I have an overflow tube that starts in the radiator fill port. Does the cylinder store the water and put it back into the radiator, or just dump it?

A hose from the bottom of the overflow tube into a container at mid or higher radiator level will accept any extra coolant and return to the cooling system when the engine cools. That is if the radiator cap to radiator does not have air leaks.