Originally Posted by Ricky Bobby

Gio the only difference the cap does is make the "safety relief" of venting pressure if it builds up to 1.4 bar instead of 2 bar, it makes no difference on normal operation of the system.

Assuming your coolant is 50/50, not overfilled, and your system is running at normal operating temps, the 1.4 bar cap will behave exactly as your 2.0 bar cap, except if there is a problem in your system and the pressure builds it will vent at 1.4 bar instead of 2.

Normal operating of the system never gets above 1.0 or 1.1 bar, assuming what I said above is correct. If you have more water in the system than coolant, higher pressures can build. If you have overfilled expansion tank, higher pressures can build.

Personally I'd rather have the "safety relief" at 1.4 bar than 2.0 bar, so I will be putting a 1.4 bar on in the coming weeks. My expansion tank, hoses and T-stat have been replaced about 3 years ago so my system is in good shape.