Q: Is this another Toyota Sienna manufacturer defect? on 2008 Toyota Sienna

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You would think that Toyota would manufacture a vehicle to survive the Western PA winter condition. Not so! My Sienna is 3 years and 2 months old with 43K miles. The A/C tubing (exposed part in the rear and beneath the vehicle) is already corroded. Dealership blames it on road salt and is asking for > $1,350 to replace the tubings, with no guarantee that it would survive more than 2-3 years. I am a mechanical engineer myself and consider this to be a costly design flaw. There is a history of corrosion with Toyota vehicles. Unfortunately, it is not going to cause a recall like the corroded spare tire cables or the rusted frame in other Toyota vehicles. But what a shame! The dealership staff has great pride of the brand and wants happy customers, but the product just does not live up to its reputation!
(2) Answers
(3) Comments
i understand your frustration. first of all, i would not use the dealer for replacing the lines. i would look at a good shop to do this for you. after the repair, you should have the lines z- barted so the salt cannot attack the lines. it will probably double the life of the lines depending on your winters.
i live in the philly area and we see tons of these issues with all manufacturers that have exposed tubing under the vehicle.

i still consider Toyota tops for there product, too.

thanks for using repairpal

Yes indeed, as Roy said -- not just Toyota has this issue. It's a fact of life, unfortunately. Being from the Pittsburgh area myself, I can tell you that PennDOT seems to be extra salt happy there...ha. Every vehicle my family has ever owned there has decayed, even with the best of undercoating intentions.

Having moved out west, I nearly forgot about Ziebart!

One other thought: Make sure when you get your car washed during the winter (which I recommend regularly, by the way), you go somewhere where they spray the undercarriage. Many of the automated washes in Pittsburgh, even, have an undercarriage wash as you drive in. It's vital that you do your best to clean off the corrosive materials. This may extend the life of your undercarriage, too, regardless of your vehicle manufacturer. Good luck!
"They all perform the same" is not a valid excuse for poor product design. Engineers are problem solvers; they can come up with a better design or at least a less costly fix. Often, it is the financial side that keeps the product from getting more robust. Car manufacturers do not want to build a car to last too long! Remembering in the 1970's and 1980's, car rust was a problem. I owned 3 cars since then (Chevrolet Corsica, Chevrolet Impala, and Plymouth Grand Voyager), none of them had rust-proofing and they survived okay. I did have to change mufflers and associated pipes once awhile, but it did not cost me $1,350 each time. I disagree that the burden has to be on the consumer side. Actually, Pittsburgh uses much less salt than Montreal and Toronto due to its mild winters. I feel sorry for the Canadian side.
i agree with not being a valid excuse, but the fact is that it is reality today and we have to deal with it.
the exhasuts systems today are stainless steel which is a reason for the higher pricing. even with that, the water inside still rots out the pipes but ata a slower rate.
it seems we get better each year with technology, but our out of pocket repair and maintenance prices keep going up. thats is something i have a real problem with myself.