Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Cooling system pressure

My Plus Six has radiator caps with the pressure indicated as 15 psi; yesterday at MMC I saw a BMW B58 engine with radiator caps (shown in the photo) which appear to be twice that pressure. Increased pressure means an increased boiling point, but also a potential stress test for any leaks on the cooling system. Is there any merit in switching from what I have to the ones MMC now seem to use?

I believe the new B58 cars have a revised radiator design which may explain the different caps.

Yes be careful in 2024 they changed rad supplier. I did notice this in your photo post as my CX likes yours has a lower pressure cap on the passenger side.

Thanks both; the car will be back with MMC in April for further tests on an intermittent drivetrain warning, accompanied by unwanted engine cutting out; they've eliminated most of the fuel system and earthing points, but need it back for a few days to complete the checks (all under warranty). I'll speak with them then regarding the caps.

Will be interesting to see what MMC say, as 2 Bar in a cooling system is pretty high, would certainly make a Trad go pop at some weak point

The manual for my 2022 cx says max coolant temp 115c which is 10 psig , so yes 2 bar is far more. But I think it is the turbo cooling circuit has the high pressure cap.

Both of my current caps show 15 psi, so indeed will be interesting to have that conversation with MMC.

Interesting. My drivers side one is the high pressure cap.

OK, as I say both of mine are 15 psi, however the Driver's side cap does appear to have had some fluids on the top causing some 'corrosion' of the cap. Perhaps it should have been a 30 psi cap, and has operated at some stage above the relief pressure of the 15 psi cap. I'll definitely investigate that further.

All other CXs I have driven have had one high pressure cap. Maybe ask a dealer before you risk any over pressure