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2002 S40 Brake Pressure S40-V40

When the car is cold, usually in the morning, I have to apply a great deal of pressure on the brake pedal to stop the car. Once the car is warm, the brakes appear to work normally. I have read that it could be the brake vacuum pump?? Not sure obviously. Any experience or knowledge in this area is appreciated. If so, is the repair complex or costly?








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    2002 S40 Brake Pressure S40-V40

    Unless technology has taken a turn for the worse, there is no vacuum pump for the vacuum assisted brakes. It uses vacuum generated naturally by the engine. There is a line from the intake manifold to the vacuum cannister with a one way valve on it. The valve could be defective, the line could have a slight leak, or a massive leak somewhere in your vacuum system.

    Joel gave good advice about flushing the brake lines, do it.

    The easiest test would be to firmly place your foot on the brake pedal and start the engine. The pedal should go down at least an inch after engine start when the vacuum pressure builds. If that doesn't happen, check the lines for a leak.

    Klaus
    --
    Common sense trumps a PhD








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    2002 S40 Brake Pressure S40-V40

    I don't know much about this specific problem, but most people either do not realize or do not care that they should be changing their brake fluid every few years. It is "hygroscopic" (I think that's the word) which means it sucks up moisture any chance it gets, and this moisture not only reduces its 'hydraulic' capacity, but also corrodes the insides of your braking system.

    Regardless of what the ultimate solution to this problem is, I'd wager you've got the original factory brake fluid in there, and you should change it with new fluid, doing a complete flush (bleed all lines out at the calipers). This will at least let you know that you're dealing with the proper 'baseline' configuration. And who knows, it might help or fix your prob too, though I think that's less than likely. I've heard of stranger things though.

    I don't know much about the S40 line, but I would expect it takes synthetic DOT4+ fluid.

    In my 1998 V70 there is one rather large vacuum hose that supplies vacuum to the brake master cylinder, and I believe it runs from the master cylinder to the throttle body area, underneath all the intake plumbing. It would be prudent to check out that line.

    Other than that I would suggest inspecting your lines for signs of 'washing' where the fluid might be leaking. You won't necessarily see any pooling under the car because the fluid evaporates fairly quickly, but it should leave a dark spot where it's leaking out.
    --
    1998 V70 AWD Turbo 190k+







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