radiator and expansion tank replacement

[sealbeach740]

I am currently talking with BMW NA regarding replacing the expansion tank when my radiator started leaking (2000 740i sport). They replaced the radiator under warranty, but since the expansion tank isn't (yet) leaking, their policy is only to replace broken parts. The rep explained (in his view) that the expansion tank only holds anti-freeze for a short time & is not under pressure like the radiator. So his theory is the radiator would be much more apt to leak than the expansion tank. But he WAS surprised the radiator (& expansion tank) are made out of plastic. I know I've seen multiple posts of people complaining that they replaced their radiator only to have the expansion tank give out shortly thereafter. I don't want to get stranded when the expansion tank starts leaking. Any ideas on what to say? I'm don't know a whole lot about the mechanicals of our cars.

[martin.w]

Well the expansion tank is under pressure all the time and thats why it has 1.5 bar pressure cap on it.!
The expansion tank is made of plastic and yes so is the radiator
and in some case they have split and leaked.
Only leaking parts can be replaced under warranty unless the Dealer is willing to do a goodwill on their own.
The reason the tank leaks after a radiator leak is because the higher temps the car was running at the time of the leaking rad only manifest after the system pressure of1.5 bar is bulit up again
and then the tank that is now dry britul gives loose.
Goodluck

[sealbeach740]

Thanks, Martin. I'm going to give BMW NA a call back & see where it goes....:eyes1

[sealbeach740]

I received a phone call from BMW/NA and after talking with some of the BMW tech guys, they decided to honor my request & replace my expansion tank for free. The representative from BMW at first wasn't quite up to speed on our plastic radiator/expansion tank issues. To be honest, I was pleasantly surprised! All I need to do now is wait until the head service guy (Mr. Tetiva, I believe) at Crevier returns from vacation in 2 weeks & set up an appointment with him. I guess it pays to pursue things if you believe you are correct. If I would have left it with the decision just from Crevier, I would have been out of luck. Can't really blame Crevier, though. They were following BMWs rules of if it aint broke, don't fix it. Anyway, 2 thumbs up to BMW/NA for standing up on this issue. Martin, thanks for your encouraging words, also.
:

[martin.w]

Your welcome and iam glad you got the results you needed.
BMW na does take care of their customers,but sometimes i little extra push is needed.
Well enjoy your BMW
Martin. :