I would think recoding the gauge to read "real" would be as valuable as tinkering with the cap vent pressure point to me.

I recoded all of my bmw's to read actual temp on the gauge so I know if things are going south before any issues.

I even installed a digital temperature gauge on my E70 since it doesn't even have a gauge at all from the factory.

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Just BMW's - All cars and trucks was two pages long
1994 318is
1997 528i
2000 323i
2001 X5 3.0 auto
2005 X5 3.0 auto
2011 535xi auto
2013 X5 xdrive35 Turbo
More are at my website

Aftermarket E53 Radio Install