'96 960 vacuum brake booster

irbyjr · Post by **irbyjr** » 05 Jun 2010, 08:04

I have an audible air/vacuum leak sound when depressing the brake pedal. Braking is somewhat delayed until I press the pedal more, then braking is better. I can find no reference to this booster part availability. What is the situation here??
Thanks

DeRail · Post by **DeRail** » 05 Jun 2010, 10:37

There's a check valve that has a vacuum line running into the booster. Most of the time from what I understand, the valve can let go and cause problems like this. In my case however, the booster (or brake servo it could be called) has an actual leak and I'll need to replace it eventually. You're better off paying the 30$ for a boneyard part or find a remanufactured unit, because new from Volvo when I checked they were extraordinarily expensive!

Remember that if you put in a new valve or take yours out to test it to put some vasoline or something on the rubber so you don't tear it

Let us know your findings,
Darrell

irbyjr · Post by **irbyjr** » 05 Jun 2010, 12:24

After the engine is stopped, and I first press the brake pedal the hissing sound occurs only briefly . Does this mean that the check valve is OK and that the booster itself is leaking internally?
Thanks

irbyjr · Post by **irbyjr** » 08 Jun 2010, 16:45

That indeed was the problem; the diaphragm was leaking. I elected to buy a used one for $75.
One local source said they no longer sell used brake parts for safety reasons.
Thanks

DeRail · Post by **DeRail** » 08 Jun 2010, 17:19

Sorry I didn't see your response earlier! I actually did check with Volvo out of curiosity and a) my dealership doesn't stock the servo for the 700 series, b) if I remember correctly they wanted $700+ for that unit. Glad you were able to find one for not too much dough! How did you determine that the diaphragm was leaking?

Darrell