I have an 87 s4 and right below the fill hole for coolant there is a plastic neck about an inch or 2 long and it attaches to the thermostat housing.It also has a hose coming out the side that leads to the reservoir. Well the "thing" has a crack in it and bubbles air and coolant. I call it the "thing" cuz auto zone and napa have no idea whats its called and dont have it. Anyone one know where they sell them at and a gasket? My first rotary so dont hate

Can get pics if needed

 

I know there was a factory recall on the 3rd gens and they replaced the plastic part with an aluminum part.

Not sure if it will fit a 2nd gen?

 

That part is called an Air Separation Tank or AST check at RX7store.net If you have bubbles it might be combustion pressure going into your cooling system, this sound similar to my problem and it might end up on an engine rebuild mine is going to the rotary shop next week. Search the forums for other people with the same problems you have. Sorry I could not help more but I own an FD and don't know much about your model/year. Good luck!

 

It's not an AST. It's simply the filler neck. You should be able to pick up a used one for cheap.
Try posting a WTB (want to buy) in the classifieds. It would help if you have a picture.
You can also try Apex Auto Parts in Oklahoma City, google it.

 

Tank for clarifying hanman, I learned something new about FC's today

 

Thanks for the help guys. Mazda sells them for $103 plus shipping but luckily i remembered there was a guy in town known for rotories. When i found his shop he had 3 fc out front and 3 inside and 2 fd that were insanely built. But yea i showed him what it was and he went to the back and grabbed one (looked fresh off a car) and sold it to me for $5. Also got a **** ton worth of info cuz while i was there i asked him ALOT of stuff XD. Anyway thanks again everyone.