jza80

iTrader: (32)

I have found that my FD is fitted with what looks like a 0.9bar pressure cap on the filler neck, and the AST has a 19psi "racing" cap from the previous owner. The car has been this way for awhile and seems to run pretty cool based on the cooling fan cycling pattern.

But, I have been reading that the filler neck cap should not have a pressure function, and just have a flat seal. Is this correct? The next question is what is a good cap for the aftermarket AST (it has a larger, normally-sized cap)? The current cap has a pressure-relief lever but I'd like to get away from that if possible.

SonicFD

iTrader: (17)

AST should have the 0.9 Cap.
Filler neck should be flat but you can put a Greddy/HKS/whatever for looks if you wish. If you delete the AST you need to have a 0.9 Cap on the filler neck.

jza80

iTrader: (32)

Thanks. It looks like I have pressure caps on both sides now for some reason.

ZE Power MX6

iTrader: (157)

19psi is a lot, maybe switch it back to a lower pressure cap on the AST. Doesn't matter what cap is on the filler neck as long as it seal, it can be a pressure cap or flat cap.

DaleClark

iTrader: (55)

You can get the "flat cap" new from Mazda if you'd like one. As stated, the pressure cap is just fine there, doesn't hurt anything.

Dale

jza80

iTrader: (32)

Thanks for all the info. I did order a flat cap from Malloy, and I am changing the AST to a 13psi cap.