My 1991 350 SDL has a serpentine belt drive system with a dual shock absorber system to take up slack and keep tension on the belt. The previous owner replaced one (maybe both) of these shocks about once every 1.5 years. Is this normal? Is there an alternative to using a part with such a short useful life?

I keep wondering if I am missing something.

Thanks to everyone. Appreciate a response to the bb as well as to my email.

George
george.stephenson@trw.com

There is only one shock, the tension is from a spring next to the shock. WE(dealer) install the idler pulley(& bracket) from the later W140 chassis S350D so that the belt doesnt jump around so much!

Thanks MB Doc
 

You are correct, of course. One tensions and the other offloads the shock, right?

If you go to later S model (140) pulley and bracket, do you use same shock and spring or part numbers for 91 SDL? What is the difference between the two? Different "net location" of the tensioner pulley taking more slack out or what?

Thanks.

George

Everything is still the same, it's a additional GUIDE pulley!