Guest Dave M. Posted December 22, 2014 Share Posted December 22, 2014 I have a 41 Caddy with new rebuilt stock engine and a clean radiator. This car is a driver and the radiator always overflows out the tube even though engine mostly stays around 160 degrees. Any solutions would be appreciated.Dave m Link to comment Share on other sites More sharing options...
The Old Guy Posted December 22, 2014 Share Posted December 22, 2014 If the radiator cap is good , it may be that you are filling the rad too full. The next time it loses coolant leave it alone and see if it stops discharging fluid. Link to comment Share on other sites More sharing options...
Guest Posted December 22, 2014 Share Posted December 22, 2014 You are probably overfilling it. Before high pressure rad caps most rads were only filled to just over the tubes. This leaves room for the coolant to expand when hot rather than overflow. Link to comment Share on other sites More sharing options...
Guest Dave M. Posted December 22, 2014 Share Posted December 22, 2014 Thanks for replies. Rad stops overflowing when top of core is visible. It should hold more fluid. Link to comment Share on other sites More sharing options...
GLong Posted December 22, 2014 Share Posted December 22, 2014 If the top of the core tubes are covered with coolant when the engine is up to temp, then it is fine. The large top tank on old radiators was for expansion, not capacity. New cooling systems don't have top tanks because the expanding coolant is diverted to a remote overflow tank, and then drawn back in when the engine cools. GLong Link to comment Share on other sites More sharing options...
Marty Roth Posted December 22, 2014 Share Posted December 22, 2014 (edited) Dave, This car takes a different radiator cap than one of the standard height. It has a greater depth than a standard cap, and your sealing surface is not contacting the area inside of the filler neck. There is nothing to stop the pressurized water from flowing out of the overflow tube above the entrance to the neck.Talk with Bob (Sr.) at Bob's Automobilia - he knows which of the caps is right for your '41 Caddy. (805) 434-2963 I had that same exact problem every time I drove my '41 Cadillac until I installed the CORRECT cap, and then drove nearly 3,000 miles on successive tours without overheating and without having to add water (except after sitting idling and inching forward in a major Northeast traffic jam this past summer) Edited December 22, 2014 by Marty Roth (see edit history) Link to comment Share on other sites More sharing options...
K8096 Posted December 22, 2014 Share Posted December 22, 2014 Marty is correct in his analysis about the cap being deeper than most caps. Also, make sure you have the correct pressure cap. I believe it should be 7 pounds. Link to comment Share on other sites More sharing options...
Marty Roth Posted December 22, 2014 Share Posted December 22, 2014 Yes, it is a 7 pound pressure, and Bob is also aware of that. The one he sent me looks as the original, and functions the way my car should have done when I first got it in 2006. Can you believe I've been going through this same problem since then, adding coolant during , and following each day of touring. The cost of the proper cap is minuscule when compared to the coolant and the aggravation.Thanks, K8096 for the validation. This FORUM is great for being able to share our experiences and I've benefited from the advice of many generous folks. Link to comment Share on other sites More sharing options...
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