Beware: if you are buying an used alum AST
 

Make sure it have a good seal between the neck and the pressure cap...I bought an used unit here and have coolant trouble since...turn out the AST wasn't holding coolant at the cap.

Look like mine was corroded dips and valley at the neck...straight antifreeze will corrode alum.

Eliminate it. One less thing to leak in the cooling system. It's like an appendix, they all have it, but when it gets sick and you remove it, it does'nt hurt anything.

Sounds like you need to demand a refund :).

I would agree but not with a rotary engine where it's running hotter than conventional engine. Air in coolant system lower boiling point and increase unwanted pressure...removing the ast is not a good choice in my opinion.

There is nothing wrong with aftermarket alum ast...as long as it is working condition.

Just becareful when buying an used unit...then again that is the chance when buying used stuff.

My rotary engine doesnt run hotter than a conventional engine. As a matter of fact, my brand new 2006 Dodge Charger runs hotter than the FD.......

My engine does not run hotter than a "conventional" engine. My engine is a internal combustion engine, a rotary. I am running a FMIC which a lot of folks here will tell you, promote high water temps. I am also running on the original radiator, 111,000 miles, and I still don't get over 210F on a 100 degree day in Chicago, IN traffic, stoped, whatever. By the way, My appendix(AST) was removed 2 years ago. Thanks Big Islands Seven for info allowing me the peace of mind to do it.

still think eliminating the AST is not a good idea...the stock plastic ast build a bad rap of splitting up...if Mazda build a metal unit this subject would never surfaced...imo.

As for comparing a rotary with conventional piston engine...my 5.0L V8 can detonate at least 10 times, a pair of $40 head gaskets would fixed it. If it overheated 10 times nothing probably wouldn't happen.

Rotary = detonate 1 time = apex seal
Rotary = overheated 1 time = cooling seal

So with that removing a cooling system component from the factory isn't a good solution...it's just a work around...there is huge diff between solution and work-around.

You can't compare the 2 of them during a det, event. Pistin compression ring is at least 1/8 inch away from flame front on a piston engine while an apex seal is fully exposed to it. However, This has nothing to do with an AST. No 7 has been destroyed by removing an AST but several have been by a failing/leaking AST. Going back to your comment about rotarys running hotter, this is only because Mazda put the minimum coolant capacity they thought would cover the requirements of the car.