Ok so I have a question that I couldn't find the answer too. When you delete the AST you need the new filler neck that is slightly taller. Is this just to make it the highest point in the system? Or am I missing something? Why is it necissary?

 

from what ive read you use the filler neck off of a 2nd gen rx7 that has the overflow nipple arttached and use a spring radiator cap

 

So its just for the overflow nipple?

 

from my understanding yes. Coolant Air Separation Tank Elimination

 

Never measured it, but believe it does make it the highest point in the system....or at least very close to the throttle-body coolant line inlet if you still have it in place.

 

The only reason to change the rad cap neck out is to use the 2nd gen part that has the nipple for the overflow. That's it.

Been running for YEARS with no AST, zero cooling problems.

Dale

 

or you can drill and tap a nipple on the one piece filler neck.

 

It needs to be a pressure nipple would it not?

 

No, the only time it has coolant flowing is when The system is venting. Coolant expands, pressure builds, lifts radiator cap, bypasses. Coolant cools down, contracts, sucks it back past the radiator cap. Just needs to be sealed. If just tapping and adding a fitting, make sure it doesn't stop the cap sealing the neck or interfering.

 

Mazda Trix

RADIATOR CAP NECK 86-88 W/ OF TUBE 15-17YA-N326 $44.64

 

you would need to find a pressure cap for this obviously, If I can't find the new filler neck locally soon, this will likely be my solution.
would the mazda part number be different from the mazdatrix? I want these parts soon and mazdatrix would take to long