96 Ford Aerostar Noise/Vibration

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#1
I have a 96 Ford Aerostar van with the 4.0 V6 engine and 4-wheel drive.

It has started to make a strange noise/vibration that has my mechanic and I stumped as to the cause. When we lift the gas pedal and decelerate, a fast-pitched vibration/noise will occur for about 3-4 seconds. It almost feels like driving over those wake-up rumble strips along the sides of the freeway. When the noise occurs, the van decelerates more than it would normally, like the van is dragging something behind it that makes it go slower. At the end of the noise/vibration, there is a slight jerk (like whatever was being “dragged” is suddenly released) then it decelerates normally. The speed range at which this happens is between 40-65 mph. When I lockout the overdrive to force it to stay in 3rd gear, the problem is the same.

This strange noise/vibration started immediately after we had the following work done (by a tire shop): new front tires, new outer tie rods, and a front end alignment. I don’t know if this problem is related to this recent work or not. When we took the van to our regular mechanic to investigate the noise, he discovered the front axles needed to be replaced along with the left inner tie rod, which he did. This unfortunately did not fix the noise/vibration.

If anyone can suggest what this problem might be based on prior experience, or suggest a course of diagnosis, my mechanic and I would be very appreciative. Thank you.
 
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#2
full time 4wd?
new tires only on front has ne thinking.....
front tires are SAME size as origional AND same as rear?
A slight differance in size @1/2" diameter may cause problems
hopefully there is no CEL/SES or ABS light on?
In mean time I will do sme checking....
 

sunny

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#3
Some of these Aerostars had a problem with the transfer case rear output shaft bushing coming lose and causing the rear driveshaft to vobrate. Look to see if you have an aluminum driveshaft installed or if it is steel. If you have the aluminum one then it has already had the update done to prevent it from occurring. If it is steel then see your local Ford dealer about an updated t-case housing and rear aluminum driveshaft install. There was a recall for it a few years ago but I don't know if they would still do it for free.
 
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#4
Thank you for your response to my question at the BatAuto website about a noise/vibration in my 96 Ford Aerostar.

I did some more checking based on your initial response and found the following information.

The new front tires have a diameter of 26 3/8". The rear tires, which have been on the van for a few years, have a diameter of 25 1/2". So we do have a diameter difference of approximately 7/8". All tires are labeled as P21570R14. We have driven the van about 753 miles since having the front tires put on, should we be concerned about damage to the transfer case at this point? Should the tire shop have been aware of this issue, and if so do you think they should be responsible to resolve this problem such as providing new rear tires or being liable for a possible damaged transfer case?

The CEL is on, the two codes are P0171 (System Too Lean, Bank 1), and a pending code of P0133 (O2 Circuit Slow Response (Bank 1, Sensor 1). The light has been on about a month, definitely before this vibration problem happened. Does it have a bad O2 sensor on the left? The ABS light is off. The 4WD drive light is off.

Thank you for your help.

Phil Riley
 

kev2

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#5
I was TOLD you only need a 1/2 inch differance to cause a problem.....BUT that was not a answewr I could qualify ...no technical information to support only a friend who is a dealer tech.

They are not going to "give" you tires, you need to have this addressed, if you do not repair a known problem why should they be responsible.... ... have you returned to address issue? remember tire shops sell TIRES more often than not they are not trained, equiped, or have the necessary technical information available to address thes issues.

That this happened after the tires were installed is reason to address the issue of tire size.

I would trouble shoot the p0171 lean before the slow response code...check for a possiable vacuum leak.
 
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#6
I checked the circumfirence of the front and rear tires and found the fronts are 82" and the rears are 80.1". I called the tire shop and talked to the manager, he said they normally recommend replacing all four tires at the same time on a larger 4-wheel drive vehicle, but he has not had this problem on an Aerostar. He said this shouldn't be a problem unless there is more than a 7% difference. I have a 2.4% difference.

I called a Ford dealership and the service advisor says max 1/4" difference in diameter.

It sounds like I need new rear tires to match the fronts?

Thank you.

Phil Riley