Ok I posted this over on a Sienna Message board but wanted to see if anyone here has an idea...
Our 2004 sienna has developed a burning rubber smell that is most
noticeable inside the cab when running the heater and when stopped at a
light.
We have almost 60k on the van and I decided to have it looked at. The
mechanic has told me they cannot find anything wrong, nothing is leaking
no coolant or oil. It is not coming from the accessory belts, so I
had then pull the timing cover to check the timing belt. They told me
the belt looked fine, no wearing or cracking, all the idlers and pulleys
looked fine as well. The water pump looked fine with no coolant leak.
They are at a loss at what it could be.
The small only happens when the van is hot, can be smelled outside the van after it has been run for a while. It is not a constant smell, it comes and goes.
The smell is only noticable with fresh air on, vs recirc.
Sounds like you have the general area pinpointed - if you only smell it when the HVAC system is set to fresh air/vent and when standing outside the car - then that means it is pulling air and the accompanying odor through the cowl area. Only thing that could producing that odor has to be under the hood or under/around the chassis/wheels.
Could be a number of things - rubber/plastic part making contact with hot engine parts (should see some damage, unless the part is under something else/hidden). Plastic bag or other road debris stuck to exhaust system. Rubber exhaust isolators could be melting onto the exhaust system. Cosmoline protectant can cause that acrid burning rubber smell as well - but generally happens on newer cars, where the protectant could be sliding off. Brakes could be sticking, but create a little different smell than burning rubber.
That is a pretty tough thing to try and pinpoint - have to catch it when it happens.
I think you if you check the things which are listed in the upper post then you will definitely got the problem. Because it may be something then rubber which you are considering. hope you will get rid of it soon. Good Luck
