vaccum system repair
 

I have a clunk in the car when the car downshifts. From researching this forum the conclusion seems to be a bad check valve (on vac line from pump to brake booster). Either this or I will have the mechanic look at the whole vac sysstem to find the leaks. How much does this service cost?Is it necessary to do this repair?I think I can live with the ,but if it ruins my tranny, this is a whole new thing all together. What's your twocent's??? Gracias. amigos!!!

Tell us what model your car is.

I have the same problem on my 89 300E since I had it back in 95. I also have bad differential mount bushing and engine mount, could they be part of the reasons?

84 300 DT
 

The car is an 84 300D Turbo with 256k. Thanks. Is there a DIY illustration on how to check the whole vac system on this car? Thanks.