[beegeezy]

I have a coolant leak somewhere on my 535i. I’m pretty sure that the overflow tank is the source, or at least one of the sources. I rented a test kit from autozone https://www.autozone.com/loan-a-tool...ece/449951_0_0 but it doesn’t seem to have the correct cap adapter. The orange (#5) bmw adapter fits and seals the overflow, but doesn’t thread on...which is useless for pressure testing. If you’ve pressure tested your F10 N55, what adapter or kit did you use?

[beegeezy]

After some time with my dremel, the orange adapter fits. It just needed some plastic removed so the adapter would go far enough in so the threads would catch.

[beegeezy]

I ordered a new expansion tank and cap from FCP Euro. Mine is leaking from the seam. I'll pressure test again after I replace the tank but hopefully that's the source (since I couldn't find anything else leaking).