Two problems related to manifold/header/muffler/tail pipe have been reported for the 2008 Toyota Sienna. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2008 Toyota Sienna based on all problems reported for the 2008 Sienna.
The contact owns a 2008 Toyota Sienna. The contact stated that while driving 55 mph, smoke began to emit from the rear. The contact stopped the vehicle and noticed that a high pressure hose under the intake manifold was pierced and leaking oil. The vehicle was towed to an independent repair shop and was in the process of being evaluated. The vehicle was not repaired. The manufacturer was made aware of the failure and offered no assistance. The failure mileage was 40,105. Updated 4/2/12.
That was around 2012 new year time when I , my wife and my kid visited our friend at atlanta, GA. We drove our van on interstate highway I-75, in the middle of our trip, our van started shaking vigorously. I felt that was from engine, it forced me to stop on the side of I-75. After a while we restarted our van, we could only drive for < 65 miles/hour. Any acceleration resulted in vigorous shaking. After we came home I drove my van to an auto service center, and was checked. It turned out that 3 ignition coils, spark plugs, and manifold gasket had to be replaced. Yesterday (9/10/2015) the same problem happened again.