Has anybody ever seen this AST? How important is the quality of the AST? This is also not FD specific.

 

it should not matter...they all work the same. the quality is in the welds

 

As long as there are no leaks, you are good to go

 

When replacing the AST do you have to drain the coolant ??

WIll alot of coolant leak out while replacing this unit?

 

as much as in the AST and a bit more

 

Unless I did something very wrong (highly likely), when I tried to replace the AST without draining the coolant I lost a lot of coolant. It kept coming out to the point that I finally bailed and crammed the hoses back on the AST. I'm now waiting until I change coolant again before I make another attempt. Keep in mind however that I'm mechanically incompetent.

 

keep the hose above the waterpump housing. if the hose is below then a lot of the fluid will drain out from there...

there's a good amount in the ast... get an old milkjug to catch the fluid.

 

Looks like a knockoff Greddy.

In my opinion it's not worth risking your engine, I would never install one of those on a customer's car. Instead just delete it altogether, the delete kit (fc filler neck) is like 30 bucks from Ray at Malloy Mazda. gets rid of a few failure points in the engine bay.

 

goodfella, could you explain that a bit more for a noob? I seem to remember something about the AST being important, but that may have just been someone's "trust mazda" argument

 

if you search this site it,s all over the place, your question will open up another ongoing argument, some say you must run an ast, others tell you to loose the ast. alot of ppl have explained the importance of it & how it works, others have good results without it. i personally deleted it & works good, all u need is a fc coolant filler neck with overflow fitting on it, run that hose to bottle, plug other lines off, bleed coolant very good. hope you like reading because i suspect this will open up a large debate lol

 

fair enough- definitely don't want to spark a debate, and I am reading my *** off in the faq section so that I don't step on any landmines. I was semi aware of the debate, I just hadn't heard of the FC tank mod. many thanks

 

i got this one from ebay, i don't think it was rx7 specific but its 3 times bigger than the stock one so it holds a lot more, nice welds and only $90.

 

That's an odd looking ast.

 

yeah well it doesn't have to be a cylinder shape to do the job it works just fine.

 

ast on roids! LOL

 

i did mine the other day w/o draining the coolant, it was hell and man am i never doing that again without draining the coolant. i lost alot of coolant and actually had to half burp the system after since i was scared i lost too much.

long story short either u better be amazing with clamping hoses shut and ramming hard to reach hoses on in tight spots, or jsut draint he coolant system and take your time.

 

Agreed. And it probably functions just fine at removing air. But just thinking that it adds a bit more resistance to the air trying to flow through your front mount and radiator. And that one probably wouldn't work on any SMIC set up.

 

I know, just saying it's odd looking.

 

It would only work on a SMIC setup if you have your battery removed or re-route it somewhere else because I couldn't fit it in there with the stock SMIC setup.

 

that has got to be the biggest AST I've seen on a FD GOOD LORD!!!. but, looks like all the piping is correct and should functions exactly like the OEM minus the cracking.

 

for the AST to work properly, the hose coming out of the bottom of the AST to the radiator must have a 0.15 inch restriction otherwise coolant will bypass the top radiator hose.

Don't believe me, cut out the OEM AST at the bottom and look at the restrictor.

 

so what AST's will work properly? just the petit, or other forum vendor asts? (honest question)

 

FWIW, also bought from Ebay a couple of years ago:

Restrictor:

 

In reality a container is just a container no matter how you slice it. As said as long as there are no leaks you should be just fine.

Where are the commonly rx7club approved brands manufactured? I'd bet a few are in China, which is where your ebay parts are going to come from anyway.