Do I have a brake servo problem?

Discussion in 'Chassis' started by Trev16v, Jul 30, 2008.

  1. Trev16v

    Trev16v Paid Member Paid Member

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    Hi all,

    I have just had the first ever MOT done my 16V G60 project MK2 and I shall be collecting it back from the garage later this week.

    Now even though the car has passed on everything, when out on the road the brakes are absolute crap. Quite scary, in fact.

    The car started out as a 16V. It has the normal rear discs on the back but with what I think are early MK3 rear calipers. At the front, I have got a 280mm G60 brake setup. The brake servo is what I believe to be a 16V item (can't be totally sure as I pulled it out of my parts bin). The 22mm brake master cylinder is brand new (and it is the second brand new one I have tried). All new pads. Many new brake lines and pipes, and there are no leaks. I have bled the system through using my Easy-Bleed many, many times over.

    The problem is that when you press the brake pedal, it does feel a little soft maybe but not quite the same as when you have air in the system (which by now I surely can't have). The car is VERY sluggish to stop, and most certainly does not give you the 'jolt' you expect when you quickly step on the brakes.

    The brake servo does certainly work because when you turn the engine off, pumping the pedal a couple of times results in a hard pedal. But despite this, could there still be a problem with the servo?

    My mate was suggesting there's a problem with how I am providing the vacuum feed for the servo. I have got the standard 16V servo hose going to the back of my Scirocco 16V inlet manifold. The pipe looks all okay to me.

    When I press the brake (when the engine is running, or when there's still vacuum left after just turning the engine off) I hear a slight hiss from down near the pedal. I initially thought this was a leak somewhere, but then I realised that my wife's Corrado makes the same noise, as does my mate's Jetta.

    Any ideas?

    Trev
     
  2. rubjonny

    rubjonny Administrator Staff Member Admin

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    as long as it was from a 1.8 MK2 it'll be the same as a 16v one, they all got the 9" servo. are you 100% sure of the condition of the pressure regulator?
     
  3. Matt82

    Matt82 Forum Addict

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    i had something similar with mine for months. tried everything, but ended up in wicks the other day, walked past some jubilee clips and thought id try one of those on the servo vac hose, where it joins the manifold.

    sure enough, my pedal is completely transformed. pedal is firmer and higher (may have to adjust the throtle cable as heel n toe is slightly off now) but one corner is still locking before the others :S
     
  4. pigbladder Forum Addict

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    theyre a complete sod to bleed well

    if in doubt about air in the system get it coasting along say 30-40mph and touch the pedal a few times without slowing the car too much , if its air the pedal will get harder and harder with each pump

    if thats the case...try the easybleed with more pressure
     
  5. Tristan

    Tristan Paid Member Paid Member

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    Also make sure you bleed it without without having the rear jacked up . The old skool way of checking a servo is ; Run engine , turn off... press pedal 4-6 times til pedal gets hard , hold pressure on pedal when it does , then start engine , pedal should sink to the floor slowly , then recover after a pump or two .
    Like the guys said, check the hoses , and also the one way valve on the hose from manifold to servo .
     
  6. prof Forum Addict

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    rear brake comp valve under load while you are bleeding it? and do you have the one way valve in the servo line?
     
  7. Trev16v

    Trev16v Paid Member Paid Member

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    Thanks for the advice so far, gents.

    Each time I renewed the brake fluid, I used the Easy-Bleed system with a relatively high pressure (up to 30psi) in the tyre. When bleeding brakes on a MK2 I always, always clamp the rear pressure regulator so that the valve is open. I've also rebuilt much of the braking system on another MK2 recently and had no trouble whatsoever with the brakes on that other MK2.

    Prof: The valve is definitely there in the servo line, but I ought to check that it works properly.

    Rubjonny: I've fitted a brand new rear regulator.

    Matt82: Most interesting idea. I'll check all the clamps.
     
  8. rubjonny

    rubjonny Administrator Staff Member Admin

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    could be air in the master cylinder itself or perhaps a bad seal between the reservoir and cylinder letting in air? Some say you should bleed the cylinder before you fit but cant say I've had problems, might be worth cracking off both the blanking bolts with the eezi bleeder attached to see if that helps any.
     
  9. c8dhc Forum Member

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    I have the same problem with my mk2 16v and could do with a little advise too.

    My car has been sat a few months + I have done a bit of work to it. My brakes are now poor (same symptoms as above) I replaced one of the rear calipers + have bled system 3 times now.

    After reading this, the only other thing that I think could be related is a vaccum pipe problem. When fitting a new air filter/modifying my filter box - to make the job easier I removed all the little pipes. I needed to tidy them up a bit anyway as they were all over the place. Im wondering if I maybe got them on wrong? Anyone got any diagrams of these?
     
  10. Imteyaz Forum Member

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    Slightly off topic, it's not too difficult to change the servo itself so why not try it. I read that the MKII Golf Auto's have a larger servo as standard (confirmed by a Haynes manual, unfortunatley I don't have one at hand but I'm sure someone can check the specs on it). Try your local breakers for one of those, it seems like you have tried almost everything else so maybe the servo is worn / faulty and in need of replacing.

    Considering you have a 16v G60, any extra braking assistance would be required in your case I would imagine....
     
  11. rubjonny

    rubjonny Administrator Staff Member Admin

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    it'll just be the bog std 9" servo as fitted to GTIs there are only 2 servos offered for MK2s, 7" or 9" :)
     
  12. Matt82

    Matt82 Forum Addict

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    after jubilee clipping the servo vac hose to the manifold, my pedal is now much firmer. it "bites" much higher and the brakes feel more effective over all

    OSR still locks up first tho haha
     

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