99 Dodge Grand Caravan AWD drive train problem

Hello all. I just purchased a 99 Dodge Grand Caravan AWD with 79K, from the original owner. The car has been well maintained with all
receipts, except for probably the most important maintenance, the transmission. I had originally thought the transmission had been flushed at 46K because there was a BG sticker under the hood. After reviewing the receipts I determined it was a BG brake line flush during some brake work. Anyway I have noticed that at between 45-55 MPH when I am applying the accelerator (even lightly) that there is a washboard like sound and vibration. It almost seems to come from the back of the vehicle but definitely sounds like the drive train. If I let off the gas the sounds disappears. The sound/vibration also seems to appear during low speed acceleration when I am turning the vehicle (though it is not nearly as pronounced). If I drive in 3 instead of D (3rd and 4th) the sound does not appear when doing 45-55. I am leaning towards the transmission, but wonder if it could be the all wheel drive system. I have purchased a new Chrysler filter, 10 quarts of ATF+3, and plan on dropping the pan this evening. I will then disconnect the cooler line from the trans and try to flush out as much of the old fluid as possible. Anyway, does this sound like a transmission problem? The car does not slip and shifts pretty smoothly.
Thanks,
Lonnie
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Hello all. I just purchased a 99 Dodge Grand Caravan AWD with 79K, from the original owner. The car has been well maintained with all receipts, except for probably the most important maintenance, the transmission. I had originally thought the transmission had been flushed at 46K because there was a BG sticker under the hood. After reviewing the receipts I determined it was a BG brake line flush during some brake work. Anyway I have noticed that at between 45-55 MPH when I am applying the accelerator (even lightly) that there is a washboard like sound and vibration. It almost seems to come from the back of the vehicle but definitely sounds like the drive train. If I let off the gas the sounds disappears. The sound/vibration also seems to appear during low speed acceleration when I am turning the vehicle (though it is not nearly as pronounced). If I drive in 3 instead of D (3rd instead 4th) the sound does not appear when doing 45-55. I am leaning towards the transmission, but wonder if it could be the all wheel drive system. I have purchased a new Chrysler filter, 10 quarts of ATF+3, and plan on dropping the pan this evening. I will then disconnect the cooler line from the trans and try to flush out as much of the old fluid as possible. Anyway, does this sound like a transmission problem? The car does not slip and shifts pretty smoothly.
Thanks,
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Dropped the pan replaced the filter and let the trans drain for a few hours. Replaced with 6 quarts of ATF+3. Ran the car for 5 minutes or so. going through the gears. Dropped pan again and drained. Replaced with another 5 quarts of ATF+3. Still have the shudder. I swear the sound seems to come from the rear of the vehicle. But it does not happen if I am in third gear at the same speed. Only happens in 4th.
Lonnie
snipped-for-privacy@yahoo.com (Lonnie) wrote in message

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4th gear only would seem to indict the Torque Converter....

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I had a similar problem, a noise and vibration under light throttle while in high gear. It was a few years ago while my '97 was still under warranty so I don't remember every detail. I could hear and feel it from the driver's seat, but it was not too bad. It was much worse sitting in the midcabin seats. The AWD cars have two shafts supported by a bearing. The shaft, I think the forward one and the bearing were bad. They were replaced under warranty. If you are not under warranty I would live with it or be prepared to part with your wallet.
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The fluid was probably replaced with wrong fluid. Get as much out as possible and refill with fresh +3 or 4. Use a MOPAR filter and do yourself a favor. GEt the Mopar reuseable gasket too. Larry

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Classic torque convertor clutch shudder. Change the fluid and filter and use ATF+4 (or +3, whichever is recommended) but NOT with Dexron III and an "additive" of any sort. That will stop the shudder.
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