aluminum AST
07-09-02, 01:03 PM
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aluminum AST
hey guys....i searched for it, buti couldnt seem to find it. i was wondering what an AST was and why many of you use aluminum ones 
07-09-02, 01:22 PM
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ast = air separator tank.
it's designed to be the highest point in the cooling system and allow the bubbles to bubble out of the coolant before it's circulated back through the system. (it is essentially just a jug that the hot, bubbly coolant drains into from the top, then exits through the bottom, hopefully after all the air bubbles have expanded out to the top of the jug - so only the bubble-less coolant exits the tank to go back through the system).
you would use an Al AST because the stock AST is plastic, which is prone to cracking (especially being that our engine bays get so hot). If your plastic one cracks, you may as well have remove your one of your radiator hoses and let all the coolant drain out while running the car. not good. Al ASTs won't crack, and therefore you don't have to worry about your coolant going bye-bye while you're sitting in traffic or tearing up a race track.
it's designed to be the highest point in the cooling system and allow the bubbles to bubble out of the coolant before it's circulated back through the system. (it is essentially just a jug that the hot, bubbly coolant drains into from the top, then exits through the bottom, hopefully after all the air bubbles have expanded out to the top of the jug - so only the bubble-less coolant exits the tank to go back through the system).
you would use an Al AST because the stock AST is plastic, which is prone to cracking (especially being that our engine bays get so hot). If your plastic one cracks, you may as well have remove your one of your radiator hoses and let all the coolant drain out while running the car. not good. Al ASTs won't crack, and therefore you don't have to worry about your coolant going bye-bye while you're sitting in traffic or tearing up a race track.
Last edited by BrianK; 07-09-02 at 01:25 PM.
07-09-02, 01:26 PM
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AST is the Air Separation Tank somewhere to the rightish of your stock intercooler (I forget exactly where, my engine bay hasn't looked like that for years) ... it's purpose is to burp the air out of the coolant. We use aluminum ones because the stock plastic one has a tendency to split the seam at the top and leak. Some people eliminate them, which I think is a mistake. You won't find one right answer about to elminate or not, just like you won't find one right answer about mineral vs. synthetic in a rotary (which is designed to burn oil and synthetic is designed not to easily burn so go figure which I use).
Last edited by DK; 07-09-02 at 01:28 PM.
07-09-02, 01:26 PM
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Damn,
What did you search for? If you search for AST you should get 100's of matches but I will humor you anyway. An AST is Air Seperator Tank. Its purpose is to remove air from coolant before returning to radiator, it also cools it down a bit. Some get an aluminum one because EVERYBODY who has the OEM unit WILL at some point intime crack the OEM unit causing coolant to flow everywhere and over heat the engine. Mine was the original, was still in good shape but when i removed the Airbox the mystery hose tore the nipple off my AST.
There is some debate whether or not the aftermarket AST will do what the stock one will do. some decide to bypass the stock unit, but I think that is a mistake. I don't trust that the aftermarket unit seperates the air, so I purchased a OEM mazda unit.
What did you search for? If you search for AST you should get 100's of matches but I will humor you anyway. An AST is Air Seperator Tank. Its purpose is to remove air from coolant before returning to radiator, it also cools it down a bit. Some get an aluminum one because EVERYBODY who has the OEM unit WILL at some point intime crack the OEM unit causing coolant to flow everywhere and over heat the engine. Mine was the original, was still in good shape but when i removed the Airbox the mystery hose tore the nipple off my AST.
There is some debate whether or not the aftermarket AST will do what the stock one will do. some decide to bypass the stock unit, but I think that is a mistake. I don't trust that the aftermarket unit seperates the air, so I purchased a OEM mazda unit.
07-09-02, 03:08 PM
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Well, I have the M2 bypass kit and NO coolant guage! Talk about an idoit! Factory guage stopped working and just go in the Auto meter guage. Well, I used a vacuum cap to close off two lines, and one cracked today and blew coolant all over the engine. Of course it was a 96 degree day, but had to drive to a funeral. Please, I know how dumb I am, but I had few choices. Only drove less than 5 mi. Seems ok, BUT I would recommend an aluminum tank, spend the extra $50 for the peace of mind!
Lets hear it for the coolent level sending unit!
Lets hear it for the coolent level sending unit!
07-09-02, 03:18 PM
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I can't believe you couldn't find this in a search... this comes up at least every week, and theres a bunch of really LONG threads discussing pros and cons of AST elimination.
Trending Topics
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07-09-02, 04:19 PM
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AST
On the contrary I just did my AST bypass last weekend and will never go back. Instead of capping the top and bottom, you can just connect both lines together, don't have to worry about popping there. A better way is put a 3/8" block and plug the hoses on both ends and lock it down with hose clamp, it will never pop.
I posted a realization that the stock AST has built in internal baffle (try blow through the nipple, barely any air goes through). Changing to metal AST is no different than doing the AST bypass IMHO.
Timmy
I posted a realization that the stock AST has built in internal baffle (try blow through the nipple, barely any air goes through). Changing to metal AST is no different than doing the AST bypass IMHO.
Timmy
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