I'm baby-sitting a friends FD for a few days while I restore his factory VR-paint, and he's been dealing with a small coolant-leak for nearly as long as he's owned his car... Anyways, since it's now in my posession I took the liberty to poke around a little bit and I noticed that *this* (little black box) is leaking and pissing coolant from between it's two "halves". That being said, I'm sure this is a common problem, so if anyone can give me some information to pass along to him, that would be awesome.

Specifically *what* is this little black box, and where is the best place to get a replacement.

Thanks!

~Erik AKA FC guy

 

I'm not really sure but never had a stock FD, so dont have one of those...i know the wankel has a harder time getting air out of the coolant system... some kinda pressure chamber...

 

that's the stock AST (Air Separation Tank), highly recommended to replace it with an aluminum one or just eliminate it because it's known to crack and break

 

That's the AST = Air Separator Tank. It's a common failure point. There are all aluminum replacements available.

 

I agree, the car should not be driven until that tank is replaced!

 

very easy fix.. tell him to do it before something really gets damaged

 

lol well now i know what its called haha ^^

 

Right on, I was telling *him* it was the AST, but I didn't want to sound like an idiot in the tech section if I were wrong. Thanks!

 

Links from heaven:

http://www.rx7store.net/category_s/63.htm
http://www.pettitracing.com/rx7/index_cooling.htm
http://www.gothamracing.com/catalog/...roducts_id=868
http://www.rx7.com/store/rx7/fdengine_cooling.html Scroll down on this one.

 

Thanks for the links man, I was going to go with Corksport (because they're close), but I think my buddy would rather spend $150 instead of $230 on an AST... Thanks!

 

Is it ok to eliminate the AST on a stock system with no adverse affect?

 

Quite a few people have eliminated them with no problems.... search around. Mine is removed and I haven't had any problems.

 

Don't you have to use the FC plastic coolant filler neck "top piece"(the little cap on top of the neck itself that you put the block-off cap on) to eliminate the AST?

 

Yes.

I plugged the AST nipple on the filler neck using this solution:
https://www.rx7club.com/3rd-gen-archives-73/ast-elimination-my-filler-neck-nipple-plug-solution-270469/

 

wow I had not seen a black one fail until today... Bah I'm sticking with my stock AST F pettit