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post #1 of 4 (permalink) Old 12-23-12, 02:54 PM Thread Starter
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ax4n problem

i know this is the taurus section, but i figured it would get a little more attention than the freestar section.

we own a 2004 freestar van with the 3.9 and ax4n.

one day while my girlfriend was driving it she told me about a noise she heard while pushing on the throttle, kind of a popping sound. well we had also just received the recall notice for the torque converter and i assumed it was related so we had the recall done.

the noise was still there. so i just thought to myself that it could be the CV axles, so i waited till i had an empty spot in my shop that i could bring it in and do some service work. over the next 2 weeks the noise got a little worse and you couldnt give much throttle at all before the popping noise happened.

so yesterday i brought it into the shop and checked the axles, they were fine. so i had a coworker get in the driver seat and power brake it some to duplicate the noise and so i could see if i could spot anything under the van. well, while we where doing that it did the noise pretty loud and something let go. the van would no longer move forward....


i decided to investigate myself instead of bringing it back to the dealer. i dropped the tranny to check the converter teeth to see if they were stripped, they were not. so, i tore down the transmission thinking maybe we grenaded the spider gears. well, ive got this thing completely torn down and the only thing i can find is about half of the material on the "coast band" was worn off and there were some heat spots on the back side of the band.

now, while i am pretty competent with a wrench, my experience with automatics internally is pretty small.

now my question is, anyone have any idea of what could have been causing the popping noise? and led to the ultimate failure? is it all all possible that the damaged coast band could have caused this?

any help is greatly appreciated. this is a bad time of year to half to buy a new transmission.
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post #2 of 4 (permalink) Old 12-24-12, 01:02 PM
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Re: ax4n problem

What band are you talking about ? There is no coast band. either thin steel or thick cast
iron. How many bands do you have ? Many things can be wrong. Could be the one way
sprag in the converter. Did you check it ? The other sprag gives you reverse so that isn't the one. If the converter sprag let go you have to strip the entire transmission and clean it and rebuild it. There will be metel filings through out the entire transmission.
You can rebuild that transmission for about $800.00 - $900.00. Plus oil and filter. If the drum on the so called " coast band " is burned with heat spots it has to be replaced. You now have a core. Examine the planitary gear set VERY carefully. If any of the center pins of the gear set are worn your transmission is junk. If you have to replace that transmission with a used one ( good luck ) be very carefull. Ford has a bad habit of
" ONE YEAR ONLY ". You had better get the proper transmission if that is the caes.
Good luck and all the best for Christmas.
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post #3 of 4 (permalink) Old 12-24-12, 07:22 PM
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Re: ax4n problem

Section D, #501
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post #4 of 4 (permalink) Old 12-25-12, 10:57 AM
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Re: ax4n problem

Chippset, the band he's talking about I think would be the low intermediate coast (see jwko's drawing), on another drawing I found, it was just called a coast band. It doesn't seem to be letting loose when it needs to be. Unfortunately, the last (and most recent) automatic I rebuilt was a Dodge 727... they've made a few changes since then. If you go to his original post, it describes more of the symptoms and how he got here.

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