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  1. #1
    Join Date
    Mar 2019
    Location
    GA
    Posts
    35

    Default I think I need to bleed my brakes

    Pedal feels spongy, reservoir still full.

    I guess bleeding is step one ( hopefully of one ) towards diagnosis.

    I have seen plenty of generic how to bleed your brakes vids on you tube.

    Anything specific for an 01 v70 xc ? Any european "eccentricities" I need to consider ?

    Thanks

    Ben

  2. #2
    Join Date
    Dec 2009
    Location
    GA
    Posts
    1,420

    Default

    Quote Originally Posted by BenF View Post
    Pedal feels spongy, reservoir still full.

    I guess bleeding is step one ( hopefully of one ) towards diagnosis.
    You bleed brakes to get air out - the question is - How did the air get in? If it's never been low enough, air has not infiltrated the system.
    So yes bleeding the brakes is a good first step, but probably not the only step.

    Have you been changing the brake fluid every few years? If not you may have a master cylinder going bad, or sometimes a sticking caliper (not sliding) can make the pedal softer (but it's rare with single piston calipers)

  3. #3
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    4,116

    Default

    Did you recently replace your pads?

    Did you put the caliper spring on correctly?

    Is the caliper spring missing?
    Current Fleet:
    2016 Tundra Crewmax 4WD 1794
    2005 MB S600 (126K, Michelin AS4, HPL 0W40)
    2005 MB SL600 (55K Michelin AS4, Mobil 1 0W40)
    2004 V70R (143K, six speed M66, HPL 5W40)
    2004 XC90 (235K, HPL 0W30 Euro)
    2002 V70-XC (295K, HPL 0W30 Euro)
    2002 V70-T5 (225K, IPD bars, Bilsteins)
    2001 V70-T5 (125K, IPD downpipe, cat back and other mods)
    1932 Packard Sedan (straight 8, dual sidemounts, original paint and interior, Shell Rotella 15W40)

  4. #4
    Join Date
    Aug 2017
    Location
    Pleasanton CA USA
    Posts
    486

    Default

    Brake fluid slowly goes bad over time, by absorbing moisture. Because of the high pressure in a hydraulic fluid, water boils at a low temp. The moisture in the brake fluid
    boils and forms pockets of gas which become compressible...this makes the brake response go soft. 40,000 mi. is a recommended interval for flushing brake lines.
    2013 XC70 T6 Flamenco Red (hers)
    2015 XC70 T6 Seashell Metallic (his)
    past: 13 Volvos going back to '74 242 sedan

  5. #5
    Join Date
    Sep 2020
    Posts
    12

    Default

    Quote Originally Posted by pbierre View Post
    Brake fluid slowly goes bad over time, by absorbing moisture. Because of the high pressure in a hydraulic fluid, water boils at a low temp. The moisture in the brake fluid
    boils and forms pockets of gas which become compressible...this makes the brake response go soft. 40,000 mi. is a recommended interval for flushing brake lines.
    This must explain what happened to my uncle's car running at 50k miles with a soft brake pedal.

  6. #6
    Join Date
    Mar 2019
    Location
    GA
    Posts
    35

    Default

    I have never touched the brake system, I don't know when if ever it has been bled / fluid changed. I agree that it maybe the master cylinder or something else, but it seems to me that step one is to bleed / replace the fluid. If the problem persists then I will start further investigation.

  7. #7
    Join Date
    Feb 2010
    Location
    Virginia Beach
    Posts
    4,116

    Default

    Quote Originally Posted by BenF View Post
    I have never touched the brake system, I don't know when if ever it has been bled / fluid changed. I agree that it maybe the master cylinder or something else, but it seems to me that step one is to bleed / replace the fluid. If the problem persists then I will start further investigation.
    When you bleed it, take good look at your front caliper springs. If they aren’t installed correctly, or have broken, you will have a soft pedal.

    In fact, post a picture of those springs here, and let me take a look. There are dozens of threads on P2 Volvos with soft brakes following DIY brake work, and it’s all from incorrect spring installation.

    I’ve had a caliper spring fail/break. Instant soft pedal.

    It could be your master starting to fail.

    I don’t expect much improvement from a brake flush to be honest. Brake fluid absorbs water over time, and causes all sorts of problems, but old brake fluid works fine from a hydraulic perspective, it doesn’t suddenly become compressible and cause a soft pedal.
    Current Fleet:
    2016 Tundra Crewmax 4WD 1794
    2005 MB S600 (126K, Michelin AS4, HPL 0W40)
    2005 MB SL600 (55K Michelin AS4, Mobil 1 0W40)
    2004 V70R (143K, six speed M66, HPL 5W40)
    2004 XC90 (235K, HPL 0W30 Euro)
    2002 V70-XC (295K, HPL 0W30 Euro)
    2002 V70-T5 (225K, IPD bars, Bilsteins)
    2001 V70-T5 (125K, IPD downpipe, cat back and other mods)
    1932 Packard Sedan (straight 8, dual sidemounts, original paint and interior, Shell Rotella 15W40)

  8. #8
    Join Date
    Aug 2020
    Location
    Seattle-ish
    Posts
    11

    Default

    Quote Originally Posted by Astro14 View Post
    When you bleed it, take good look at your front caliper springs. If they aren’t installed correctly, or have broken, you will have a soft pedal.

    In fact, post a picture of those springs here, and let me take a look. There are dozens of threads on P2 Volvos with soft brakes following DIY brake work, and it’s all from incorrect spring installation.

    I’ve had a caliper spring fail/break. Instant soft pedal.

    It could be your master starting to fail.

    I don’t expect much improvement from a brake flush to be honest. Brake fluid absorbs water over time, and causes all sorts of problems, but old brake fluid works fine from a hydraulic perspective, it doesn’t suddenly become compressible and cause a soft pedal.
    I'm coughing to the left in my sleeve (in embarassment) on one point. Mr. Tomcat always has sage advice. I did a pad change a few weeks ago as the sem-metallic Jurid pads were just eating the rotors. I had the rotors turned and put in ceramic pads, and the pedal is a *little* softer and the braking not as firm. But in the process, I lost the LF spring in some ivy on the side of the driveway and after 1/2 hour of hunting for it, I said, "I'll just find it when the RoundUp kicks in next week." Which I did. It's still in the glove compartment waiting for the tire swap in a few weeks to go in. Despite a lot of years (decades) of wrenching, I assumed it was a squeal device and wouldn't affect feel like that. Live and learn. Thanks for teaching, Astro.

    However, I will comment constructively on this:

    but old brake fluid works fine from a hydraulic perspective, it doesn’t suddenly become compressible and cause a soft pedal.
    agree 100%. And unless you are an experienced wrench, I don't advocate doing a brake flush vs. a better way that exists. Siphon out your fluid reservoir, clean it the best you can (if needed), then put in fresh fluid. This alone will drop your fluid water content by 1/2. The reservoir fluid will mix with the system fluid over the course of time as the MC piston activates. It won't be instant, but it will get into a homogenous mixture after enough driving. It's been tested and shown to work. (If you doubt this, look at a diagram of how an MC piston works and you see it will). If you need to see it, this tedious video will walk you through it:

    https://www.youtube.com/watch?v=Xk2zGvKfrhc

    The reason this is good is that you can do it cheaply two, three times and drop your fluid content down to near zero and never risk introducing more air into the system via bleeding. Bleed screws are finicky and being slightly loose with the wrench on them can get air sucked back in via the threads on them VERY easily. Unless you suspect a bad bleed job was done and there's air in the system, a few drain/fills on the reservoir will get you right. I live in the PNW (Seattle area) and maintain a lot of cars and motorcycles. Just dumping the reservoir annually and refilling is all it takes to keep everything 5x5.

  9. #9
    Join Date
    Mar 2019
    Location
    GA
    Posts
    35

    Default

    Thanks all interesting stuff, so I had a go at this last night and can report some good progress, the travel has reduced and a short test drive felt better, I will monitor it over the next few days ( does anyone else find themselves so hyper vigilant on a test drive that its hard to be objective ).

    Anyway, the fluid in the reservoir was a horrible black color and some rusty looking crap and big air bubbles came out of the calipers. That said I might try again as it was a bit of a comedy of errors.

    1. I made tube in bottle type device and had the tube going in a really tight fit to the lid and neglected to make a breather hole, so when I took it off the first one I made a nice brake fluid fountain!
    2. My floor jack leaks like ****
    3. The back drivers side wheel did not want to come off, I resorted to driving around my neighborhood with really loose lugnuts to break it loose.
    4. So I forgot about the springs because I was racing the dark by the time I got the front.

    But to astro's point. The brake pedal didn't suddenly become spongy, it probably always was a bit and in the last couple of weeks just got to where I had the occasional moments doubt as to whether or not I was going to stop. Basically it was a very gradual process of going soft.

  10. #10
    Join Date
    Dec 2010
    Location
    Cumbria, UK. Maine USA.
    Posts
    513

    Default

    Quote Originally Posted by BenF View Post
    3. The back drivers side wheel did not want to come off, I resorted to driving around my neighborhood with really loose lugnuts to break it loose.
    Refreshing to see someone who actually thought about it and decided on a method to solve this rather common problem rather than brute force and destructive remedies.
    Current Junk: Couple of worthless rusty old clapped out Volvo bricks, XC70's 02, 04 & Countless P.O.S's, Rust buckets, Junk cars,( 50W Oily cesspool Sludge) Stolen and other assorted rubbish cars, 1928 Jed Clampett Tourer, (8 hole cast iron lump, original rust and decay, 40W Straight Bacon Grease),

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