93 volvo 940 wagon brake prob.

My daughters 93' 940 wagon seems to have a brake pedal that changes height. It seem to start stopping the car lower in the range than than usual. here is the weird thing . It only does this occasionally.

I checked for vacuum leaks and have disconnected the brake vacuum booster after sitting all night and it still has the big suction sound. so it isn't leaking. not low on fluid and we have not added any.

Any Ideas are appreciated. Bob

Reply to
Sailor
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From what you are stating here it sounds as if the brake master cylinder is starting to go bad you need to have this corrected soon either by yourself or a local Volvo repair shop /or dealer

Reply to
Glenn Klein

Normally the booster doesn't cause the pedal to drop.

Besides the obvious master cylinder suspicion, it can be sticking slide pins in the front calipers - especially if the low pedal height includes a pull to one side when braking. If it pulls to the right the problem is in the left caliper and vice-versa. In my 85 765T I had my daughter gradually depress the pedal while I tried to turn the wheels one at a time. The right front still turned by hand when the pedal was all the way down! I had to drive the slide pin out with a mallet. If this is the problem, be sure to have both front calipers cleaned and lubed. The rear doesn't use floating calipers on my model; I'm assuming yours is the same. Otherwise the rear calipers are under the same suspicion.

Mike

Reply to
Michael Pardee

While you are at it, flush and change the brake fluid as it sounds as if it has started to become contaminated with water. As the fluid is Hygroscopic (ie absorbs moisture) it should be changed every two years (Volvo recommendation).

Cheers, Peter.

Reply to
Peter K L Milnes

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