MRG1965 Posted September 26, 2016 Report Share Posted September 26, 2016 HI all, silly question time again. Was topping up the coolant, engine oil etc on Saturday, and noticed that the pressure cap has a 10 on it. I'm assuming this is 10psi, which seems a little high to me. It does not seem to be causing any issues, but I was wondering if this is the correct pressure cap for a standard (as far as I know)1964 TR4. Any help, as always gratefully received. Mark Quote Link to post Share on other sites
peejay4A Posted September 26, 2016 Report Share Posted September 26, 2016 7 is normal iirc. Quote Link to post Share on other sites
stuart Posted September 26, 2016 Report Share Posted September 26, 2016 Should be 4lb Im afraid for all 4 cylinder cars. Stuart. Quote Link to post Share on other sites
RogerH Posted September 26, 2016 Report Share Posted September 26, 2016 Hi Stuart, Moss show 7lbs for the 4A - is this not right then. Roger Quote Link to post Share on other sites
tim hunt Posted September 26, 2016 Report Share Posted September 26, 2016 I've had a 7psi cap on my 4A ever since acquisition in 1970. I always thought this was the received wisdom for the 4A. I note that Rimmers list a 4lb cap of 1" depth for 2,3 and 3A and a 7lb cap of 1" depth as an option on 2,3 and 3A and apparently standard on TR4 with filler neck. For the TR4 without filler neck a 7lb cap of 3/4" depth is standard with the option of a 13lb cap of 3/4" depth. For the 4A Rimmers list a 7lb cap of 3/4" depth as standard and a 13lb cap as option. Make of that lot what you will! Tim Quote Link to post Share on other sites
stuart Posted September 26, 2016 Report Share Posted September 26, 2016 (edited) Workshop manual lists 4lb for TR4 with no revision for 4a.You can run what you like but thats factory recommendations. FWIW it probably was the difficulty of getting 4lb short reach caps that is why most supply a 7lb. Stuart. Edited September 26, 2016 by stuart Quote Link to post Share on other sites
Richardtr3a Posted September 26, 2016 Report Share Posted September 26, 2016 Anything over 4 lbs can cause leaks. i had that problem on my 3A Stuart is usually right. Richard & H. Quote Link to post Share on other sites
MRG1965 Posted September 26, 2016 Author Report Share Posted September 26, 2016 Hi, as always, much appreciated, I think :-) So anything from 4 to 13lbs. 4 sounds a little light, but the 10 I have on it sounds too much, god knows where the pressure would go with a 13lbs cap on it. 7lbs cap sounds like a good compromise. I'llget one to see what if anything happens to the temperature or the overflow. Cheers Mark Quote Link to post Share on other sites
BlueTR3A-5EKT Posted September 26, 2016 Report Share Posted September 26, 2016 (edited) Hi Stuart, Moss show 7lbs for the 4A - is this not right then. Roger According to the parts lists..... 137691 (GRC112) is listed for TR4/4A/250/5/ & early 6 which is a 7 lb cap. (TR6 went over to 13 lb later in its life) It is a 3/4" reach cap with 7 lb pressure release. This I believe fits the radiator without the extended header that a sidescreen car has. The earlier one for TR4 is a 1" reach cap with 7 lb release. Sidescreen cars had the 1' 1" reach 4 lb cap. Peter W Reach symbol corrected - Thanks Brian Edited September 27, 2016 by BlueTR3A-5EKT Quote Link to post Share on other sites
peejay4A Posted September 27, 2016 Report Share Posted September 27, 2016 (edited) I've posted this before but here goes again. Don't go above 7psi if you have a sleeve/bellows thermostat or it won't open. Edited September 27, 2016 by peejay4A Quote Link to post Share on other sites
BlueTR3A-5EKT Posted September 27, 2016 Report Share Posted September 27, 2016 I've posted this before but here goes again. Don't go above 7psi if you have a sleeve/bellows thermostat or it won't open. Thanks for that reminder. Peter W Quote Link to post Share on other sites
BrianC Posted September 27, 2016 Report Share Posted September 27, 2016 Sidescreen cars had the 1' reach 4 lb cap. Peter W That will be to the bottom of the rad then Quote Link to post Share on other sites
RogerH Posted September 28, 2016 Report Share Posted September 28, 2016 Quote Link to post Share on other sites
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