len1 Posted August 16, 2019 Report Share Posted August 16, 2019 so , just doing final checks before our trip tomorrow to IWE and the not very old radiator cap decides to fall apart in my hand, so only option is use my Stag one even though its rated 20lbs. Can anyone confirm this will be ok , pretty sure it will but another opinion would be nice Len Quote Link to post Share on other sites
Fireman049 Posted August 16, 2019 Report Share Posted August 16, 2019 (edited) Hi Len ~ I think you'll be OK with the Stag rad. cap. Using a higher pressure cap raises the boiling point of the cooling water. Make sure the spring lengths are the same. I use a 13 psi. cap on my 3A with no ill effects. I believe the 'normal' cap pressure is 4 psi. Regards ~ Tom. Edited August 16, 2019 by Fireman049 Quote Link to post Share on other sites
len1 Posted August 16, 2019 Author Report Share Posted August 16, 2019 thanks Tom appreciated Len Quote Link to post Share on other sites
Fireman049 Posted August 16, 2019 Report Share Posted August 16, 2019 Hi Len ~ You're welcome. Replace the cap with a correct one as soon as possible. You don't want to risk burst hoses because of the higher pressure. Regards ~ Tom. Quote Link to post Share on other sites
len1 Posted August 16, 2019 Author Report Share Posted August 16, 2019 yes. i will replace it as soon as i get to Stratford upon Avon ! Len Quote Link to post Share on other sites
Mike C Posted August 16, 2019 Report Share Posted August 16, 2019 Maybe also check the hoses and clamps if you expect the engine to get hot on the way. Quote Link to post Share on other sites
Waldi Posted August 17, 2019 Report Share Posted August 17, 2019 Hi Len, When your hoses are in good condition I would not be concerned. But replace it by the 13 lbs (not the 7lbs) cap once you have that. Does it have the same internal spring loaded valve a std TR6 cap has? A normal cap does not have that, so water cannot overflow. Have a nice IWE. Waldi Quote Link to post Share on other sites
Z320 Posted August 17, 2019 Report Share Posted August 17, 2019 Hi, the rad cap is not the reason for the pressure, but the amount of enought air in the system (do not overfill the rad) and the water temperatur. Ciao, Marco Quote Link to post Share on other sites
Mike C Posted August 17, 2019 Report Share Posted August 17, 2019 Waldi raised a good point. If you have an overflow bottle fitted you a cap fitted with the springs and seals to feed coolant into the overflow outlet rather than just vent it out of the cap onto the road. Quote Link to post Share on other sites
len1 Posted August 17, 2019 Author Report Share Posted August 17, 2019 Am at Stratford now no problems .temp stayed normal. Cheers Len Quote Link to post Share on other sites
Fireman049 Posted August 17, 2019 Report Share Posted August 17, 2019 Hi Len ~ If you have a closed circuit cooling system fitted then the radiator should be fitted with a plain (non-pressurised) cap and the overflow tank fitted with a pressurised cap.. Both my 3A and 'E'-type are fitted with this system with no problems. Tom. Quote Link to post Share on other sites
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