I know all the sites that sell them say they are a really important upgrade, but is it really?

 

I bypassed mine.
If you want to keep an AST, then I wouldn't suggest the stock AST. The stock AST is known to split under prolonged high temperatures.

 

Yes it is. The stock one can crack and leak and then there goes 4k for a new motor!!! You could also just go with the ast removal, but I think Mazda designers put it there for a reason.

 

It is used to help get all the air bubbles out of the system...you can delete it as well with no ill effects but a lot of people feel safer with it....I deleted mine and no problems so far

 

if you want to keep the AST then get it. But i recommend ditching it. I have been doing that on every FD i get thru the shop and had it on mine that way for 3 years. NEVER a cooling issue!! NEVER Not a single degree hotter. So everyone that is going to come on here saying that the mazda engineers are the smartest people around please stay home They lacked alot of real world skill. These masters of engineering couldn't even figure out the Plastic and horribly hot temps under the hood are a bad combo. Yeah they are the bast around.

 

well im kind of new to rx7s so bear with me, but where is the ast located? Is it an easy install?

Also, how hard is it to bypass and what would be required to do so?

 

it mounts to the side of the factory intercooler. It is a odd shaped container with a radiator cap on it. It shouold be some sort of faded black color 3 hoses are attached to it. If you keep it and replace it you will need to drain a little coolant out of the system. Then take off the hoses from the old AST then put them on the new AST. Then refill the coolant sysytem. Pretty straight forward stuff.

Eliminating it requires the use of a 86-88 rx7 radiator cap assembly.( it has a overflow nipple on it) And some hose plugs to cover up the nipples that are stock AST hoses.I can email you some photos of it eliminated if desired PM me your address.

 

ok i took a look at it and it seems that in order to bypass it i would just connect the longer tube going into the top of the ast to the radiator right? Then what would i do with the tube going to the air pump? I am planning on removing the pump very soon anyways. So what would i do with the tube from the ast to the pump when it is removed?

 

there is NO hose going to the air pump from the AST.

There are 3 hoses from the AST.

1.) One off the bottom to the radiator. Plug that at the radiator.

2.) One from the sidde of the AST to the filler neck of the water pump. Cap that at the filler neck nipple ( hoses with bolts in the end works for plugs clamped on both ends of course)

3.) Next the hose from the top of the AST goes to the overflow tank in front of the passenger side tire. THAT hose NOW will go to the overflow nipple on the 86-88 cap assembly. That just bolts in place of the stock filler cap assembly

Like i said above. PM me your email and i will send some pics. The air pump plays NO role in the AST system. Totally different

 

ok #2 is the one that confused me. Then how would you bypass it. I have to head out now so i will check this out later. Thanks for the help!

 

you just put a hose with a bolt or other suitable plug onto the nipple that is coming out of the thermostat housing/filler neck area. It is pointing straight at you looking from in front of the car.

you want to avoid "looping" any of the lines because you will create a hot spot of coolant that does not get circulated as well as it needs to.

 

and with the other two lines? Would i just ditch the shorter of the two and connect the one coming from the wheel well to the radiator?

 

line that comes from wheel well goes to the top nipple by the radiator cap and the second line under you can either block it off just like the radiator nipple or hook it up to the radiator like I did...you can see in the picture which line goes to the overflow tank..

 

Here is a pic of my old stock setup with a tripoint ast. it is very well made..

Mikey

 

Ok so if the AST is supposed to get rid of the air bubbles in the system, wouldn't it be best to have it if you do alot of work to your car and flush your coolant regularly? If you didn't get all the air out, then the AST would take care of it correct? If so, I think for the avg. person that doesn't do their own work, would be better off keeping it. You never know if the shop you took it to got all the air out of the system. Now if you do your own work, then I wouldn't see having one being that much of a benefit, since you'd know if you didn't get all the air out. Well atleast i'd hope so.

-Alex

 

One thing I would like to add, is Mazda Changed the design of the water pump/thermo housing. And there is no longer a black plastic bolt on nipple/cap assembly. Its a solid piece..... I just found that out last night looking at my block.