Q. I read your column all the time and love it so when this problem came up with my van, I thought, who better to get a straight answer from than you.
Some history -- in July I purchased a 2007 Toyota Sienna certified vehicle from a Toyota dealership. The van had 70,000 miles and was in excellent condition. Shortly after taking possession (and a road trip), I noticed between 30-35 and 45-50 mph (especially 1,300 to 1,400 rpm) there was a louder "droning noise," as Toyota calls it. Along with this noise was a vibration that reverberated throughout the cabin and was felt in my seat.
I should mention that right after I purchased the van, I had a set of Hankook H737 Optimo tires put on with an alignment.
The first time I took the van back to the dealer, they indicated they could not find a problem and they would want to try driving another van (same year, mileage, model, etc.) to determine if this is just how the van operates. They did not have such van at the dealership.
I investigated online and found a van with all the same specs at another dealership and took it for a test drive. That van did not have the louder humming and vibration at those speeds. I took the van back to the dealership and they looked over the van again and found that the transmission fluid was "black" (I was upset about that especially because this was a certified vehicle and that should have been checked before they sold it to me) and that it was probably the cause. They did a complete transmission flush no charge
When I picked up the van, I wasn't more than three blocks from the dealership when I noticed the same occurrence of the humming and vibration. I returned to the dealership. The technicians consulted with their Field Technical Specialist and opened a case report. They determined next that it was the center front motor mount that was the cause of the problem. They replaced that part at no charge.
When I picked up that van and drove it a few blocks, the same noise occurred. I returned it to the dealership. After discussing it with the specialist again, they decided to adjust and reposition the exhaust mounts. This did solve the 30-35 mph hum and vibration, but did nothing for the 45-50 mph problem. So once again I returned to the dealership and they again contacted the specialist.
This time the dealership contacted me and stated that upon review for that model year and engine that this problem has been brought up with Toyota, they investigated it, and tried to identify the problem but were unable to. So the dealership told me in so many words that "there is no fix for this problem" and that Toyota is aware of it. I feel as though the dealership doesn't want to spend any more time on my issue because this was not the first time the specialist was involved and if there were such a documented problem within Toyota, then why didn't they tell me that the first time the specialist was involved
I would have thought if the 30-35 mph noise/vibration was eliminated by adjusting the exhaust, that some further manipulation of the exhaust or replacement of the entire system (which is still under warranty) would solve the problem. I've read online of similar issues with noise/vibration at certain rpm resolved by an exhaust system fix.
I'm hoping you might be able to confirm this is a documented issue with Toyota and hopefully have a fix for this type of a situation.
A. Thanks for reading the column and for a great question.
First, I had one of my technicians check our online sources to see if there were any known or common problems with your van relating to vibration issues. While we found nothing on our normal technical forums, it seems Toyota has not been able to figure out the problem. On a simple Google search I found a lot of Sienna owners who have gone through the same thing you experienced. Most of what dealers are finding is related to an engine vibration or the transmission of vibration through the body of the van via the exhaust system, causing some harmonics.
The majority of responses I found seem to relate to the exhaust system. These problems can be hard to pin down. Exhaust pipes that touch, and motor mounts can be the source of the problem. Sometimes it can be as simple as some loose heat shields. Now that the droning sound at the lower speed is corrected, I wonder if the other noise is more related to the rolling of the van, like a wheel bearing or maybe even tire noise. A technician should be able to determine if it is a rolling vibration or more of a harmonics in the body on his test drive.
The way you worded your explanation it seems you did not notice this initially. Is it since the tire replacement? With so many folks complaining about this issue I would love the opportunity to drive your car and see if I can get anywhere with it.