BMW 200 Rated Header Tank Cap

[courier118]

Any benefit or downside to using a header tank cap rated 200 as fitted to BMW Z4?

Neighbour has a 3.0 Z4 and he was checking his water level the other day and the header tank was fitted with a very clever float device that when you release the cap a float level stick pops up out of the neck.So when it rises you know the level is full,if it doesn't rise then you know its low.It was then I noticed the cap is rated 200 and it is the same as on our cars.

Just interested to know if anyone knows if it can be used to benefit our cars or not

[T-Cut]

I guess it saves you actually looking in the tank after removing the cap.

A 200 kPa pressure cap is made for cooling systems designed for running up to that pressure (30psi approx). The implication is the engine is allowed to run hotter than one designed for a lower pressure. You'll find this in systems intended for higher performance and a higher operating norm. While the theoretical difference exists, I doubt you'd notice any significant difference in the way things work with a 75/ZT. The engine won't run any hotter and the coolant won't increase in pressure (unless it's regularly releasing pressure from a 120 cap, in which case there's problem anyway). If you do have a leak, then allowing the release pressure to go higher may not be for the better.

TC

[courier118]

Didn't think it would make a lot of difference,it was curiousity more than anything.

Cheers