BobDeSoto Posted March 30, 2023 Report Share Posted March 30, 2023 1951 totally stock six cylinder with a new radiator. Upper hose is hard after a drive. What radiator cap should I use? Quote Link to comment Share on other sites More sharing options...
rallyace Posted March 30, 2023 Report Share Posted March 30, 2023 The system is not pressurized so use a vented, non pressure cap. NAPA should have one. Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 30, 2023 Report Share Posted March 30, 2023 (edited) 23 minutes ago, rallyace said: The system is not pressurized so use a vented, non pressure cap. NAPA should have one. Not true on my 51 Plymouth, he has a 51 Desoto. I want to say mine used a 7lb cap but I am not 100% sure on that. Looks like a 4lbs, 4th column is a Desoto 6, first column is Plymouth and it is a 7 Edited March 30, 2023 by Sniper Quote Link to comment Share on other sites More sharing options...
BobDeSoto Posted March 31, 2023 Author Report Share Posted March 31, 2023 So, is a 4# cap a good compromise between vented and pressurized? Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted March 31, 2023 Report Share Posted March 31, 2023 According to myy Atlas catlaog here is the proper cap for your desoto Find your model year and the last column on the right is rad caps So for 1951 Desoto the proper cap is an R-8 cap. Rich Hartung desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted March 31, 2023 Report Share Posted March 31, 2023 Here is a way that for most people to get the information they need. i alwasy do a search on Ebay for an item so look under Desoto 1951 radiator cap. If a listing comes up then open the item to get more info. sometime the seller even puts the supporting documentation online. This is a great way to build up your own personal library about your car. Rich Hartung Quote Link to comment Share on other sites More sharing options...
Sniper Posted March 31, 2023 Report Share Posted March 31, 2023 22 hours ago, BobDeSoto said: So, is a 4# cap a good compromise between vented and pressurized? No, it is not a good compromise. It is what is called the correct part per the factory parts manual, see the listing in my last post. Quote Link to comment Share on other sites More sharing options...
Doug&Deb Posted April 2, 2023 Report Share Posted April 2, 2023 My 52 Coronet calls for a 4# cap. When I ordered a new one from Bernbaums they sent a 7# cap. When I questioned them they said that was correct. I’ve not had any issues with it but I do have an aluminum radiator. Not sure if that helps or not. I would check the parts book and see what is specified for your car. Quote Link to comment Share on other sites More sharing options...
Doug&Deb Posted April 2, 2023 Report Share Posted April 2, 2023 According to the parts book 4# from 49-52 and 7# from 52-54 DeSoto 6 Quote Link to comment Share on other sites More sharing options...
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