Solidtrance,
I posted the following and was advised to look you up. The topic is a Gen 1 (2004) Mazda 6.
Help, Issue is cap for brake master cylinder. I have an 04 V6 AT. The master cylinder cap does not lock on, it just spins. THERE IS NO WAY IT CAN LOCK. The teeth on the cylinder that would engage the cap are on the outside of the reservoir facing out AND the teeth on the cap are facing out as well. There is no way they can engage.
I had the fluid changed a few years ago by the dealer, no issues. I just changed it again today, and that was when I noticed it. I have never lost any fluid, so there was no reason to mess with the cap (you can see fluid through side of reservoir).
I can tell you that an 04 RX8 cap fits perfectly and locks down.
Any ideas would be appreciated.
Thanks,
Mike