breaks go to floor 93 940 wagon

js_pierce · Post by **js_pierce** » 14 Sep 2008, 20:25

When I get on the breaks they go to the floor. If I pump them few times I can get more resistance. Initially I thought that the master cylinder was bad. I replaced it. I have bled all of the lines for air and checked all wheels for leaks. None observed.

The only break component that I don't know what it does is a 'cone' that sits on the firewall where the master cylinder is bolted into. It has the linkage to the break pettal. What does it do? If it were bad would it cause a soft pettal that could be pumped up?

Thanks for your help

DeRail · Post by **DeRail** » 15 Sep 2008, 00:23

Welcome to MVS!

That conical unit behind the master cylinder is your brake booster. It attaches to a vacuum line and assists in braking. It's my understanding that if the booster fails, you will get the opposite effect: a stiff brake pedal.

Other than what you've tried (bleeding, etc), I'm not sure what else to try, then again I'm just a volvo guy trying to help out, but not an expert.

js_pierce · Post by **js_pierce** » 15 Sep 2008, 06:00

thanks

Post by **billofdurham** » 15 Sep 2008, 11:53

By those symptoms you still have air in the brake lines.

The best way to bleed the brakes is with a pressure bleeder which can be obtained at most parts stores.

Whichever way you choose to bleed the brakes do them in the order - Left Rear; Right Rear; Right Front; Left Front.

On the 940 with a live rear axle it is recommended that you remove the pads from the rear wheel that you are bleeding and press the pistons back as far as they will go and wedge them so they do not move as you apply pressure to the system. Of course Volvo have special tools for this but they are not necessary if you take care not to damage the dust seals.

If the front calipers are of the two piston type you need to open both bleed valves on the caliper at the same time. Attach the bleed tube to the bottom valve and place paper around the top valve to catch any fluid that is ejected.

Bill.

wojeepster · Post by **wojeepster** » 16 Sep 2008, 06:31

If your brake fluid level is going down you have a leak somewhere. A common place is the brake safety junction block. (It leaks where the electrical connection goes. If this is the case unscrew being careful not to loose the plunger and spring and wrap with teflon tape a few turns, problem solved. If you look on the inside of all four wheels you may find a leak elsewhere although this is not as common and you have already eliminated brake master.