I found the below, and was wondering if there really is a pill / restrictor in the hose from the coolant-filller-neck to the AST ?

I have the stock hose and never felt one. Was the restrictor in the plastic tank nipple ?

Does the Pettit aluminum AST have a restrictor built-in ?

Is it even necessary ?

Does anyone run the valve during track days ?

Thanks,
:-) neil

 

IIRC, the restriction was in the AST nipple. The concern was that aftermarket AST's did not have this restriction in their nipples for that line. I don't know if you'll "need" it. I have not know too many people who have added the restriction back in after going with an aftermarket AST.

 

When I had a custom ast made I had the guy make the restrictor(exact diameter of original) and press it in the nipple for the ast. My thoughts are that "mazda took the time to mold that brass piece in it for a reason" I put brass in bold because I wonder why they just didnt make the hole of the nipple that diameter. I guess they wanted to make sure it is an exact diameter.

As far as the shut off valve it could be true maybe the factory heat valve does not close all the way or maybe with age they dont work properly. However I think if that was the case then the a/c would not be as cold as it is. But I am just guessing.




John

 

The pill appears to control the flow of water by passing the radiator via the AST---so do you want a 0.070 in. orifice or a 0.250 in. pipe by-pass?

 

When I got the Pettit AST, I made a pill and pushed it into the hose from the AST to the radiator.

 

Can you please explain how you made the pill? material and dimensions?

 

Brass, 0.070" ID I think, to match the orifice in the OE AST, and OD large enough to be tight in the hose (I don't remember the exact dimension). Length ~ the same as the OD.

Dave

 

This is just a thought... What if you took the stock plastic ast and broke the brass restrictor out of it and then put that in the hose so there is no need to make one.

This is assuming that you dont care about the stock ast and that the brass restrictor's O.D. is bigger than the I.D. of the hose. You could just file it down to fit properly.

John

 

Is the stock AST restriction in the hose/nipple from the radiator to the AST, or the hose/nipple from the filler neck to the AST?

 

It is in the bottom pipe of the AST(connected to radiator).But it is moulded in the pipe.

 

I glued restrictor in pettit nipple. used Epoxy, has worked fine for last 5 years.

 

^ Thats good to know so people dont have to make one themselves.


John