Pre-war (up to 1942) Coolant

[KC Tom]

I read somewhere on this forum that it is a good idea to run a hose from the heater return fitting to where the temperature sending unit attaches to promote Coolant circulation between banks on a flathead. Anyone have experience with that?

[James Landi]

Hi Tom,

I'm not familiar with this work around; however, I'll respectfully make a couple of suggestions having encountered burnt valves, cracked cylinder heads, warped blocks and blown head gaskets. Items of concern: rust in the block, oxidizing in the radiator core, and any and all particulate that clog passages between the block and cylinder head as well as degrade the efficiency of the radiator are common problems that are often overlooked. Purchasing a good infrared thermometer (gun) will reveal the actual destructive hot spots.  Hope this helps,  James 

[KC Tom]

Thanks for the thoughts. I have infarad and will check that.

[Brad Ipsen CLC #737]

Keep the water flow as Cadillac engineers designed it.  There are different size holes on the left and right head outlets to balance the flow to each side.  Putting an external bypass between the heads would upset this design.   

[LaSalle5019]

Food for thought - you can gain close to a 20% improvement in your cooling system by switching from 50% glycol to 100% water. This is due to water's superior heat transfer characteristics and lower viscosity. Of course there are drawbacks....no freeze protection and no corrosion protection.

On both of my 1920's cars I use 100% water and use No-Rosion as a corrosion inhibitor. I do this as I like the improvement in cooling performance, I do not run either car in the winter (live in Michigan) and I have heated winter storage.

On my 1939 LaSalle, I run about 20% glycol and 80% water. I use No-Rosion to prevent corrosion. I run this car up to the first snowfall so like some freeze protection (good down to about 15 deg F). But I really like the fact that I only lose about 5% cooling capacity vs 20% using the typical 50/50 glycol mix during summer use. Of course, the heated garage in the winter enables this. This car runs at normal operating temperature, even when the outdoor temps are in the 90s.

I mention all this as some people live in warmer climates and would stand to benefit from improved cooling performance by reducing or eliminating the glycol in their system. Just make sure you add a corrosion inhibitor. No-Rosion is my "go to" inhibitor since I have many years experience with it. I add it to my everyday drivers that run glycol, for improved protection.