Toyota Sienna AWD Problems/Questions

loucapriloucapri Member Posts: 214
edited March 2014 in Toyota
I notice my AWD sienna has a leak from the rear "gear box?"
it's kind of a clear fluid.
I used to own a AWD Town and country and I had the same problem. Not sure if it is common to AWD


  • cableguy06cableguy06 Member Posts: 299
    I, too, had a 2002 T&C with AWD and a 2005 XLE Limited AWD Sienna. You should NEVER see a leak from the gear box so take it back to the dealership as you may have a bad seal or another problem that I would think you'd want fixed before the snow comes :)
  • loucapriloucapri Member Posts: 214
    I got it fixed under warranty. But it took me whole day to explain to them "the leak is in the rear" and they kept calling me and told me they didn't see any leak (becauae they kept looking at the oil pan near the engine)
  • cableguy06cableguy06 Member Posts: 299
  • loucapriloucapri Member Posts: 214
    I know the AWD gets less than the FWD but shouldn't be that much.
    We got a disappointed 16mpg in avg.
    I am not sure how my wife drives the van but I will consider "normal" driving with 70% freeway. Don't know why and what to do to improve the mpg. any idea?
    Maybe the run-flat tires?
  • loucapriloucapri Member Posts: 214
    Can anyone owns a AWD sienna shares there real experience with the van? I just want to see how they perform. Does the AWD sienna drives well on snow (that's prettly much the reason why we bought the AWD version, right?)

    Please share your opinion.
    FYI, I know AWD won't stop better so no need to talk about that part.
  • wheels13wheels13 Member Posts: 51
    After driving 40 miles in heavy slush the next morning I went to use the car it made a very loud sound from the drive shaft hitting the body. Drove anyway, kill or cure, and later found that the drive shaft in the center of the car was packed tight with frozen slush. Had to crawl under with a hammer to clear away the ice riding on the drive shaft. Have any other owners of this 2006 LE AWD seen this problem? The car has been around a few years? Thank you
  • loucapriloucapri Member Posts: 214
    was it cold outside when this happened?
    If you drove in heavy slush, sounds like the weather is not that cold.
    I remembered I couldn't steer my car when living in eastern washington many years ago but only happened under cold cold weahter because the ice built up around the front suspension.

    I don't think you need to worry about this because the worst case is the drive shaft got stuck and the lost of AWD for a while until everyting melt
  • mleonardomleonardo Member Posts: 45
    My AWD sienna handles very well in the snow. I run studded tires on seperate wheels in the winter and the van has never broken loose. It even handles well without studded tires. I have had a few problems however with the van in general. Number one is the tires! I HATE runflats. If you get a flat on the interstate, your stuck! Those tires will not hold up at 55 mph with no air pressure And you have no spare. I went around and around with Toyota about this and got nowhere. Another problem is the fuel mileage is HORRIBLE! My window sticker said 18mpg city and 24mpg hwy. That is an all out lie! I barley get 18mpg on the highway. This thing gets the fuel mileage of a V8 with nowhere near the power. My last complaint is the quality of the interior. Mine is falling apart. The leather cover on the driver's headrest is coming off. A panel on the driver's side of my dashboard keeps popping loose and the seat release on the rear seat keeps coming out of its mount. People make fun of domestics but I had fewer issues with a GMC that I sold to buy this van.
  • wwestwwest Member Posts: 10,706
    Your realization of poor FE is more the responsibility of the US Government than Toyota. Our government REQUIRES the manufacturers to test for FE under unrealistically favorable circumstances and then FORCES them to publish the results.
  • wwestwwest Member Posts: 10,706
    "..worse case is the drive shaft got stuck..."

    In that case the vehicle would be entirely NO GO.

    If the front wheels rotate but not the rear then the AWD tarction control system will apply the front brakes along with dethrottling the engine. If that doesn't work to "force" the rear driveshaft to turn you're dead in the (frozen) water.
  • mleonardomleonardo Member Posts: 45
    Yeah Im sure Toyota was sick with guilt being FORCED to publish numbers so favorable to their sales. I guess thats where they get their great reputation for fuel economy.
  • lazzarlazzar Member Posts: 1
    How good is the non AWD in terms of handling and getting stuck in the snow.

    We live in NH and not sure we can afford the AWD version.

  • ateixeiraateixeira Member Posts: 72,587
    Consider snow tires as an alternative, that might be a little cheaper. You do get traction and stability control.

    Still, I'd spring for a low mile CPO AWD model. Should cost no more than a new one, and the warranty is effectively longer in most cases.
  • siennaswedensiennasweden Member Posts: 7
    Does anyone now what kind of differential thats in the 2007 awd?
    Electrical or something else?
    How fast does the awd comes on if a weel starts to spin?
    And how are the normally spread on the driveshaft 50-50% or 70-30% or something else.
    Thanks for any replays.
  • ateixeiraateixeira Member Posts: 72,587
    It's a full-time viscous coupling.

    Basically the power goes to both axles (50/50 by default IIRC), and when one rotates at a speed quicker than the other, they temporarily lock together.

    The fact that it's full-time means it's pro-active and should be very effective.

    Combine that with traction and stability control and if you get stuck, it's your own fault. ;)
  • wwestwwest Member Posts: 10,706
    The viscous coupling was dropped from the Toyota/Lexus (FWD)/AWD drive train across the board in '04 and while it was again adopted for the RX350 I haven't seen anything (I checked)for the other FWD/AWD products.

    Absent the VC you have a simple open differential with a slight overdrive ratio to the rear such that you get a little extra "kick" at the rear when TC activates and applies brkaing on the front, presumably slipping, wheels.

    That same overdrive ratio results in a normal F/R torque distribution of 95/5 absent TC intervention. And even with a VC it takes several seconds for the VC to stiffen up enough for a maximum of 75/25. Those numbers were obtained with my '01 AWD RX300 on a 4 wheel dyno so later VC formulations, say an RX350, may vary.

    In my judgement the FWD version with VSC/Trac will give just as good, maybe better, wintertime performance as would an AWD absent the VC. If the VC is again being used the fluid formulation has likely been changed for the better.
  • ateixeiraateixeira Member Posts: 72,587
    I don't think the Sienna changed, even though the RAV4 did, for instance.

    This article says it's still old 50/50 type system:
  • siennaswedensiennasweden Member Posts: 7
    Ok thanks
    It seemes to be a rather old solution of awd.
    Volvo uses the Haldek much quicker system.
    Its a long time left to winter here in sweden ,but i will let you now what i think about it when it comes.
  • loucapriloucapri Member Posts: 214
    Prior to the LE AWD, we had a Town and Country AWD and it worked better than a Jeep (I am not kidding. A Jeep and a Ford Explorer tried to make the hill near my house and both failed but my T&C had no problem going that hill and I got to get home)

    The LE AWD works great on snow but I believe FWD works fine on light snow based on what other posted.

    If budget allows, get the AWD. We got our 04 used with 40K miles (we could have gotton a 06 12K mile FWD) but my wife and I decided to got the AWD since we don't have any 4WD or AWD at home.

    One caution about the AWD is the run flat tires. They are pricy and don't last that long.
  • ateixeiraateixeira Member Posts: 72,587
    You also can't get the 8 seat model. That's the reason I passed (we also have a Subaru in our fleet, so we have a snow car already).
  • wwestwwest Member Posts: 10,706
    Apples and Oranges....

    Our 2000 AWD T&C has a VC, viscous coupling, to the rear driveline that is ALWAYS in effect at a reasonably high level, additionally the fluid is obviously formulated to have a very high "attack" rate, rapidly increasing torque coupling coefficient, upon front wheelspin.

    Whereas the Sienna has a simple open center diff'l and relies on TC braking (and engine dethrottling) to apportion engine torque to the rear driveline ONLY AFTER front wheelspin/slip occurs.
  • ateixeiraateixeira Member Posts: 72,587
    Actually, this article implies the Sienna still uses a full-time system just like Dodge's. I'm not sure there is any difference.
  • subewannabesubewannabe Member Posts: 403
    Our 2005 SLE AWD has 45,000 problem-free miles if you discount the run-flats that Toyota replaced at 24,000 miles under the revised bumper-to-bumper warranty. We live on top of a ridge in mountainous WNC, and AWD is more of a precaution than a regularly-needed feature, because our snow is rarely more than 6 inches at a time and it melts quickly...but it is a real issue when your are climbing a winding, 14 % grade to get home.
    I have never spun a tire in the snow or slush or off road when camping. The ride is a little too low to attempt serious off-roading in a Sienna, but its the most reliable people and luggage hauler on the market that isn't a giant SUV. We have made trips to SC beaches, the Gulf Coast of Florida , Louisiana and Michigan, and the same car that enables our family to quietly and comfortably eat up interstate at at 75 mph (while my wife reads or works on the laptop via wireless data modem,my mother-in-law reads or sleeps, the 17 yo and the 11 yo watch DVD's or listen to whatever they want on headphones) also allows us to ride along with a great sense of safety and security in snow and heavy rains. The seats are so comfortable and supportive that I choose to drive the Sienna on my business trips to Eastern NC, etc.
    My average over 45,000 is 18.9MPG, and we get around 22 MPG on long trips with 5 people and all the luggage, etc. That is the same as my other vehicle , a 2004 Subaru Forester XT, which requires premium fuel. The Subaru is a lot more fun to speed up, down and around mountain roads, but it was a crowded, packed situation going to the beach.
  • wwestwwest Member Posts: 10,706
    If you don't already have the practice of shifting your F/AWD Sienna into neutral as you approach a curve on your downhill drive when the roadbed is slippery you might want to consider adopting same.

    Or just keep this thought in mind when the day arrives that your F/AWD Sienna begins to PLOW toward the outside, DROP-OFF side, of that curve.
  • ateixeiraateixeira Member Posts: 72,587
    I don't see how that would help, to be honest.

    Keeping it in gear and using engine braking will shift the weight forward, reducing understeer. Tapping the brakes may help, too.

    If you put it in neutral and coast you will have to use the brakes alone.
  • wwestwwest Member Posts: 10,706
    "Keeping it in gear and using engine braking will shift the weight forward, reducing understeer."

    Yes, that is true, VERY true, right up to the point wherein the level of roadbed traction is no longer sufficient to support both the braking and lateral (stearing/directional) loading.

    Believe me, it WILL happen. You can either be prepared for the event, ready to quickly shift the transaxle into neutral (as recommended by the AAA), or have previously shifted onto neutral. A second bit of advice is that if you do not have VSC and your FWD or F/AWD vehicle begins to understear then you can apply the e-brake, parking brake, lightly to slow the vehicle just enough, hopefully, to bring the vehicle back into control.

    With VSC the rear brake(s) will be applied automatically in this instance.

    "If you put it in neutral and coast you will have to use the brakes alone."

    Yes, but you can alleviate the effects of actual braking virtually INSTANTLY. Alleviating the adverse effects of braking on the front tires by shifting the transaxle into neutral and then waiting for the transaxle to actually complete the shift is not so quick.
  • ateixeiraateixeira Member Posts: 72,587
    Fortunately VSC is now standard. Overdue if you ask me!
  • subewannabesubewannabe Member Posts: 403
    I drove a Ford Explorer right off the side of the mountain in low 4WD 1st gear, at 5 mph, at the hairpin directly below our house. My neighbor did the same in her AWD Outback. In addition to verifying our life insurance and building a retaining fence with locust logs, metal posts and anchored cable, we did a survey and I believe WWEst is exactly corect. When you are in a steep descent and have ABS and VSC, the best thing you can do when descending a steep grade on a low traction surface, in addition to not letting your speed get too high to start with, is put the tranny in neutral and let the computer adjust your brake effort.
    Juice, great to see another guy with a Sienna/Subaru family!
  • ateixeiraateixeira Member Posts: 72,587
    Yep, the van has served us well.

    We liked the Tribeca but it just isn't big enough for what we wanted. This weekend we took another family with us to our beach condo, 3 hours each way, and everyone was comfortable, with room for their luggage.

    When it snows, we have the Legacy. My wife stays home, so we really don't need 2 AWD vehicles.
  • automan12automan12 Member Posts: 10
    Is the transfer case required a separate oil or is it a part of transmission?
  • ateixeiraateixeira Member Posts: 72,587
    I'm not sure, but I imagine the system is sealed. You'll probably have to change the gear oil in the rear differential, though.

    On my Subaru it was fairly simple, remove two bolts, drain, replace one bolt, fill, replace the 2nd bolt. The "fill" part is a little tougher than it seems because if you are under the van you have to pump oil up into it, but I got a $7 hand pump that did the job.

    Synthetic gear oil was $4 for the one quart required, so we're talking about an investment of a whopping $11. ;)

    Gear oil stinks to the high heavens, so take a shower before you come in contact with your significant other. :D
  • wwestwwest Member Posts: 10,706
    No "transfer" case in the traditional sense, but a PTO, Power Take Off, case. And yes, it is separately lubed, with fairly heavyweight gear oil, but I doubt if it needs to be serviced EVER. At ~65,000 miles the gear oil in my 2001 AWD RX300 PTO case (includes VC, Viscous Clutch) remained clear and non-odorous. Yes, I said CLEAR.

    Silicon gear oil..??

    And gear oil doesn't STINK unless it has been subjected to extreme HEAT, which is not the normal case.
  • ateixeiraateixeira Member Posts: 72,587
    Oh, man. You should have seen the stuff that I drained out of my Miata. Just 26k miles, too. To be fair, it was 8 years old. It has a viscous limited-slip rear diff, FWIW.

    It looked like melted chocolate, too, coming out.
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