Hi
I'am having the same problem with a 2009 Sienna LE, i am still trying to get an answer.
I can even feel the vibration of the engine on the steering wheel, i think it's related to air system because when i touch the hoses, they seem too choke a little bit...
Dealers (3 of them) keep saying that it's normal...but i know it's not.
Last month, i test drove another Sienna 2009 and it's smooth as silk... :disappoin

 

i have a 08 model and it has a tappet sound when cold, but as it warms up it runs very quiet as my 02 model did.

I thought i might change the oil/filter and add some lucas oil stablizer to the oil.

Could be a tappet or loose exhaust manifold. vehicle has 48K miles,
unit was a rental so no telling how it was treated!!!

may wish I had not bought a rental unit.

 

The new 3.5 is by nature a much more mechanical sounding engine than the 3.3. There is alot going on in there. {3 timing chains}

 

I would buy that IF i hadn't test drive another 09 Sienna that runs as smoth as a Camry...
I think my problem is related to the idle because sometines the car is starting to have inconstant idle...but only a couple of times...

 

My problem is that even when it warms up, it only decrease a little bit but the vibration is still there and is so annoying....
My car has 9200 miles

 

Same thing with me. I have a 2008 model and it has a rattling or tappet sound when cold, but as it warms up it runs very quiet.

It has 49K miles and was a rental unit when I purchased it.

I do not know what I should do.

 

Same thing with me. I have a 2008 model and it has a rattling or tappet sound when cold, but as it warms up it runs very quiet.

It has 49K miles and was a rental unit when I purchased it.

I do not know what I should do.

My 08 LE now has 52K, it also was a rental, I just changed the oil and put in Valvoline 10w30. That is the oil I use in all my vehicles, just guess I am more used to the noise as I no longer notice it.

Van runs great and mama loves it, the 02 had a quieter engine, but that engine had the timing belt, this engine has a timing chain, that may be the reason for a bit more noise.

So far I am just driving it and not worring about the additional start up noise, it runs great and we get 26mpg on the road. Its quiet, with michelin tires, on a good road you better not play soft music or you will go to sleep.