2012 Toyota Sienna Power Train

Rear axle coupler assembly (part number 41303-28013) making very loud noise and vibration.

The contact owns a 2012 Toyota Sienna. The contact stated that the rear differential was making an abnormal whirling and grinding sound. There were no warning lights illuminated. The contact called the local dealer but the vehicle was not diagnosed or repaired. The manufacturer was notified of the failure and referred the contact to NHTSA. The approximate failure mileage was 79,000.

Vehicle began 'whirring' metal noise from underneath. Local mechanic said it was coming from rear differential. I took it to a Toyota dealer, they said rear differential coupler needs replacing ($2159) and drive shaft ($992). It seems the bearing ring inside this sealed unit has failed. Noise is continuous while driving, concern of part failure - we are taking vehicle on family vacation. Researching on - line it appears to be common problem with the Sienna's. Toyota had same issue with RAV 4's and issued recall but have not for the Sienna's. I called Toyota corporate in TX (got up 3 levels) to no avail, and it curt tone, they said they cannot help. Based on other similar stories on line from other Sienna owners, this seems to be a common very expensive design flaw problem with this vehicle.

MY 2012 TOYOTA SIENNA RECENTLY BEGAN MAKING A LOUD WHINING NOISE FROM THE REAR AXLE AREA. UPON INSPECTION, WE WERE INFORMED THAT THE DIFFERENTIAL UNIT WAS FAILING AND NEEDED TO BE REPLACED. THIS WOULD COST US BETWEEN $2,500-$3,000. AFTER SOME RESEARCH, I DISCOVERED THAT THIS IS A COMMON PROBLEM WITH THE SIENNA, LIKELY CAUSED BY A DESIGN FLAW. THE SAME UNIT WAS USED ON THE RAV-4, AND AFTER SIMILAR PROBLEMS SURFACED IT WAS RECALLED AND FIXED BY TOYOTA. GIVEN THE DANGER POSED BY FAILURE OF THIS PART TO A FAMILY VEHICLE, AND THE KNOWN EXISTENCE OF THE PROBLEM BY TOYOTA, IT SEEMS OBVIOUS THAT IT SHOULD BE IMMEDIATELY RECALLED AND FIXED BY THE MANUFACTURER.

SERVICE TECH AT THE TOYOTA DEALER SAID MY ELECTROMAGNETIC COUPLER / VISCOUS COUPLER AND DRIVESHAFT UJOINT SEIZED. AFTER FURTHER RESEARCH ONLINE IT SEEMS ITS COMMON. WONDERING IF TOYOTA WOULD PUT OUT A RECALL?

SAYS MY REAR DIFFERENTIAL - VISCOUS COUPLER- IS BAD AND NEEDS TO BE REPLACED AT A COST OOF AT LEAST $1,300 AND THAT DOESN'T INCLUDE INSTALLATION. HAPPENED JUST AS CAR WENT OVER 100,000 MILES AND IS COVERED IN RAV 4 BC HAD SAME PROBLEM BUT NOT 2012 SIENNA NOTHING HAPPENED EXCEPT IT SUDDENLY STARTED NOT BECAUSE OF ANYTHING I DID.

THE REAR VISCOUS COUPLER ON THE AWD HAD GONE BAD AND NEEDS REPLACEMENT. THIS PART IS THE SAME DEFECTIVE PART ON THE RAV 4 THAT HAD AN EXTENDED WARRANTY COVERAGE DUE TO BAD DESIGN BUT IS NOT COVERED ON THE SIENNA. THIS PART NEEDS A RECALL.

THE BEARING FOR THE VISCOUS COUPLER HAS GONE BAD. IT WHINES LOUDLY WHEN IN MOTION, AND THE VOLUME CORRELATES WITH THE SPEED. ACCORDING TO FEEDBACK FROM ONLINE THIS ISSUE HAPPENS A LOT. TOYOTA WILL NOT CHANGE THE BEARING ($50 PLUS LABOR). THEY WILL ONLY CHANGE THE WHOLE COUPLER ($1800 PLUS LABOR) AS THEY STATE THE COUPLER IS NOT SERVICEABLE. MULTIPLE PEOPLE HAVE SERVICED THE WORKING COUPLER TO CHANGE JUST THE BEARING. TOYOTA RELEASED A SIMILAR TSB FOR THE RAV 4 WHERE THE COUPLER FAILED.

UNIT IS PRODUCING A SPEED DEPENDENT WHINE FROM THE REAR DIFFERENTIAL CONSISTENT WITH A BEARING FAILURE IN THE VISCOUS COUPLER. ISSUE FIRST OBSERVED WITH APPROXIMATELY 98,000 MILES ON ODOMETER. THIS APPEARS TO BE A COMMON COMPONENT FAILURE ON MANY TOYOTA AWD VEHICLES MANUFACTURED IN THE LAST 15-20 YEARS, AND THE COMPONENT IN QUESTION MAY BE UNDER-ENGINEERED TO PERFORM AS EXPECTED IN NORMAL DRIVING CONDITIONS. REPLACEMENT PART COSTS $1300+ FROM TOYOTA, NOT INCLUDING INSTALLATION. *TR

MY 2012 SIENNA AWD XLE HAS 103K MILES AND HAS A WHIRRING NOISE COMING FROM THE REAR DIFFERENTIAL AREA FOR A WHILE NOW. THE PITCH AND VOLUME IS PROPORTIONAL TO SPEED AND IS LOUDER AS SPEED INCREASES. MY RESEARCH TELLS ME THIS IS A COMMON DEFECT WITH THE COUPLING BEARINGS IN FRONT OF THE REAR DIFFERENTIAL. IT SEEMS THAT RAV4 OWNERS GOT A RECALL FOR THE SAME ISSUE, BUT SIENNA OWNERS DID NOT. TOYOTA HAS REDESIGNED THIS PART ON LATER MODELS TO AVOID THE ISSUE. HOPE YOU CAN GET THIS RESOLVED. THANKS.

FRONT AXLE LEAKING FLUID

REAR DIFFERENTIAL HAS FAILED AT ONLY 60K MILES. WELL DOCUMENTED ISSUE FOR AWD SIENNA MODELS YET NO RECALL ISSUED. SAFETY CONCERN FOR THIS FAMILY OF FIVE.

WHILE PARKED, DRIVER BEGAN EXITING VEHICLE AND VAN BEGAN TO ROLL AND CONTINUED TO ROLL WHEN GEAR SHIFT LEVER CONFIRMED IN PARK AND BRAKE CONTINUALLY PRESSED, EVENTUALLY HITTING A HOUSE.

REAR DIFFERENTIAL COUPLER DYSFUNCTIONAL WITHOUT NO REASON. ALL OF THE SIENNA ESPECIALLY AWD ARE SUFFERING FROM THIS ISSUE.TOYOTA DENIES TO COVER IT.