20's truck radiator retrofit

[MaxwellFox]

Since I got my truck running and up to temperature today I want to explore something.  It currently has a 53 GM radiator with a soldered on model T neck with an overflow tube on the side of the upper tank.  First I'm considering sealing off the overflow tube as I'm worried its limiting an already limited radiator capacity.  Just let it run with the cap off until it stops bubbling over and keep it at that level.  Second, without the rear overhanging tank would this radiator even have enough capacity to do the job?  Please note radiator in the background.

[donk]

   Slip  a correct size rubber gas line hose over the top of the overflow tube, if you can and cut off what is not needed.

[MaxwellFox]

Im not quite sure what you're suggesting.  It currently has a bump on the very top of the top tank with a soldered nipple on the side of that bump with a metal tube running down the length of the radiator.  My concern is that bump arrangement is below what could be the maximum fill level for the radiator so I'm losing water capacity, probably a pint.  You can barely see the bump on the right side of the filler neck under the cowl and the tip of the hose poking out on the bottom right by the frame

Edited February 16, 2021 by MaxwellFox (see edit history)

[Bloo]

There has to be airspace at the top of a radiator. Old vehicles like that are not sealed systems, so the overflow tube should just go in high somewhere.

 

The overflow tube should always be open to the top tank, and not arranged like a modern car where coolant has to blow past a pressure cap to get out the overflow tube.

 

As long as the water covers the top of the tubes so that the core is full you are not losing cooling capacity. The top tank should be mostly air with the engine cold. It is space for the water to expand into when it heats. That is by design.

 

When the water expands, if it has nowhere to go it will pop the radiator like a balloon.

 

[MaxwellFox]

Sounds like a plan.  Thanks

[icerolyuk]

On 2/16/2021 at 3:34 AM, Bloo said:

There has to be airspace at the top of a radiator. Old vehicles like that are not sealed systems, so the overflow tube should just go in high somewhere.

 

The overflow tube should always be open to the top tank, and not arranged like a modern car where coolant has to blow past a pressure cap to get out the overflow tube.

 

As long as the water covers the top of the tubes so that the core is full you are not losing cooling capacity. The top tank should be mostly air with the engine cold. It is space for the water to expand into when it heats. That is by design.

 

When the water expands, if it has nowhere to go it will pop the radiator like a balloon.

 

My Maxwell 25 1920 rad has the overflow pipe high in the neck of the filling tube about 1” lower than the cap  and a rubber  tube running down the side of the rad