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Broken AST at 98,000 Miles

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Old 01-29-09, 03:33 PM
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Broken AST at 98,000 Miles

The OEM AST on our '94 broke off a hose nipple (left pic below) yesterday. The failure was identical to one whose picture I had downloaded from this forum about a year ago (right pic below). Ours went 98K miles, so I ordered another OEM part rather than an all-aluminum one from the aftermarket. Price was $124, or $133+ with tax. If the new one goes even half that mileage, I'll be satisfied with my choice. The original part no. was N3A1-15-35XA; the new one will be a -35XB. Either it's an upgrade or a different vendor... the part will be in Saturday. Fortunately the "Low Coolant Level" buzzer and light came on, alerting my wife, who stopped immediately and had the car flat-bedded to our house. I had originally guessed at a radiator hose or the radiator itself, considering the mileage on the car, but I guess we will get off easily this time.
Attached Thumbnails Broken AST at 98,000 Miles-broken-ast.jpg   Broken AST at 98,000 Miles-broken-ast-pic.jpg  
Old 01-29-09, 03:37 PM
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FYI Ray at Malloy Mazda sells a factory coolant hose kit w/ all hoses for ~165 or so. If your hoses are original, you may want to consider this a warning to start giving your coolant system the attention it deserves. Also get the factory clamps as they have the correct torque and install much easier in those hard to reach places.

Its cheaper than the flatbed.
Old 01-29-09, 03:48 PM
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Thanks, gracer,

The hoses are original, but outside of that I drain and flush coolant regularly, and the hoses are in good shape. When one goes I will replace all, but that hasn't happened yet.

The flatbed was only $27... we are AAA members, and that was the "more than 7 miles" fee.
Old 01-29-09, 04:16 PM
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I just bought the 14 piece cooling hose kit from Mallory Mazda (Ray Crowe, PM) and the current price was $176.91 plus shipping. Delivered in 2 days to FL. Great service.
Old 01-29-09, 04:55 PM
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Wow at that price, I really dont understand why you don't go aftermarket.
Old 01-29-09, 05:10 PM
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Originally Posted by wstrohm
The hoses are original, but outside of that I drain and flush coolant regularly, and the hoses are in good shape. When one goes I will replace all, but that hasn't happened yet.
IMO, you are asking for trouble doing that. In particular, the turbo-coolant hoses tend to get brittle and fail, causing at least a gradual loss of coolant. And condensed (the water will evaporate) ethylene-glycol is flammable, so the puddles of it that gather near the turbos with a gradual leak can ignite and cause a fire. That has been documented, and was one of the reasons for the pressure cap being downgraded to 13 psi (cooling-system recall).

I took the time in 2005 to replace all of my coolant hoses at only 55K miles, because, IMO, it was not smart to ignore potential trouble (your hoses are now 15 years old) when it has occurred many times and can be prevented.
Old 01-29-09, 05:13 PM
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People still run the plastic AST on these cars?
Old 01-29-09, 07:04 PM
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wtf? The stock plastic AST. wow. You really need a Aftermarket one, if you care about your cars health, and reliability that is.
Old 01-29-09, 07:19 PM
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Originally Posted by wstrohm
Ours went 98K miles, so I ordered another OEM part rather than an all-aluminum one from the aftermarket. Price was $124, or $133+ with tax. If the new one goes even half that mileage, I'll be satisfied with my choice.
Yeah bud, I would send that back and go after market. You would be more satisfied to know that you will probably not have to think about it again. for anouther $20 you could pick up a new aluminum one from pettitracing or the likes.
Old 01-29-09, 07:22 PM
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aftermarket alum ast isn't always the answer...

3 yrs ago I got this mysterious loss of coolant that took 4 wks to resolved.

The problem was a tiny cracked Pettit alum ast (at the neck)

Zero problem with stock 54K miles ast...in Texas summer heat.

Free AST for any1 that willing to pay shipping. Paid 85 bucks for it LOL!
Old 01-29-09, 07:34 PM
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Originally Posted by tphan
aftermarket alum ast isn't always the answer...

3 yrs ago I got this mysterious loss of coolant that took 4 wks to resolved.

The problem was a tiny cracked Pettit alum ast (at the neck)

Zero problem with stock 54K miles ast...in Texas summer heat.

Free AST for any1 that willing to pay shipping. Paid 85 bucks for it LOL!
So - one cracked aluminium AST (perhaps the first I have heard of in five years on this board) vs., oh, hundreds of reports of plastic AST ruptures? Including the one on my car before I bought it.

You sleep through statistics class?
Old 01-29-09, 07:46 PM
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Well my FD average 750 miles a year...it's always well maintain so the ast may last 100K miles...46K away LOL! or approx 46 years...LMAO!

To me crack stock ast are due to lack of regular maintenance and inspection.
Old 01-29-09, 07:57 PM
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Plastic ASTs fail because a large number of heat cycles causes them to crack. Maintenance has nothing to do with it. 3 and 5 series BMWs have the same problems with plastic end tanks and overflow tanks - they die at 50k or so miles no matter how well the car is maintained.

Inspections do not always reveal cracks because they often occur along seams.
Old 01-29-09, 08:32 PM
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I have to disagree...

Plastic ast break because of extreme heat cycle...that is true. Heat kill stock ast.

But what are the main cause of extreme heat? Low coolant, wrong coolant/water ratio, clog radiator, malfunction fan, crack hoses, etc...are these not part of regular maintenance and inspection?
Old 01-29-09, 09:02 PM
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not only that, these cars run hotter than pistons dont they?
Old 01-29-09, 09:04 PM
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On my car when I bought it, I found in the paperwork that the factory ast was replaced at about 60,000 miles cause it ruptured. My car now has 90,000 miles and the new ast already had cracking on it and it was falling apart!!!

Thats why I replaced it with the Fighters Aluminum AST, it has a billet filler neck and tig welds all around. When I had my coolant leak from the turbo coolant hoses, it leaked VERY slowly and intermitently for about 2 months, but I didnt know anything was wrong, because it didnt leak all the time, till one day when I actually smelled coolant in the interior vents, then I knew something was wrong. By now I replaced all my coolant hoses in the entire car and it was a pain but its worth it especially if you drive it a lot
Old 01-29-09, 09:26 PM
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Originally Posted by moconnor
So - one cracked aluminium AST (perhaps the first I have heard of in five years on this board) vs., oh, hundreds of reports of plastic AST ruptures? Including the one on my car before I bought it.
Well OF COURSE you've heard of hundreds of plastic ASTs rupturing. Mazda installed tens of thousands of them.

You sleep through statistics class?
What's that saying about black kettles and pots?
Old 01-29-09, 10:02 PM
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Originally Posted by Rx72Heaven
wtf? The stock plastic AST. wow. You really need a Aftermarket one, if you care about your cars health, and reliability that is.
still got my original one, 116,000 miles and no cracks yet.
Old 01-29-09, 10:04 PM
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I have several used ones . Do people buy used ones in good shape ?
Old 01-29-09, 10:27 PM
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Originally Posted by JM1FD
Well OF COURSE you've heard of hundreds of plastic ASTs rupturing. Mazda installed tens of thousands of them.
Mazda sold approx 13,000 FDs here in the U.S., not tens of thousands.

Originally Posted by catch-22
still got my original one, 116,000 miles and no cracks yet.
In the near future I can see you pulled over on the side of the highway with tons of white smoke coming from under your hood and a cooked motor. Not trying to be harsh, but why haven't you gotten rid of it?

Originally Posted by GARCO MOTORWORKS
I have several used ones . Do people buy used ones in good shape ?
I wouldnt sell them unless they're really low mileage David. Sometimes you have to save people from their own stupidity.

Guys, I've seen numerous stock plastic ASTs rupture and ruin perfectly good motors. If it's a cost issue, then just delete it altogether with an FC filler neck, which you can get from Ray for about 35 bucks.

Last edited by GoodfellaFD3S; 01-29-09 at 10:44 PM.
Old 01-29-09, 11:09 PM
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Originally Posted by tphan
I have to disagree...

Plastic ast break because of extreme heat cycle...that is true. Heat kill stock ast.

But what are the main cause of extreme heat?
A turbocharger and a rotary engine.
Old 01-29-09, 11:23 PM
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Originally Posted by GoodfellaFD3S
In the near future I can see you pulled over on the side of the highway with tons of white smoke coming from under your hood and a cooked motor. Not trying to be harsh, but why haven't you gotten rid of it?
Well in order for that to happen car would have to drive. But u are correct that thing has got to go. im just trying to finish my project up and a running mobile is top on the list.
Old 01-29-09, 11:23 PM
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¿¿What are pistons??

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Originally Posted by moconnor
A turbocharger and a rotary engine.
Correction: 2 turbochargers and a rotary engine.
Old 01-30-09, 12:58 AM
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Originally Posted by catch-22
still got my original one, 116,000 miles and no cracks yet.
Not sure that's safe. It hasn't cracked yet. Well when it does (And it will) are you willing to possibly loose your motor? if so then Thats awesome! Go stock plastic AST!
Old 01-30-09, 01:02 AM
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#1 Its normal for the plastic ast's to break.


#2 For less than $200, its worth just replacing all of the hoses. Call Ray Crowe.

Hose failures can cost you your engine. If your temp gauge moves AT all, your engine is already dun-fer


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