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brakes need lots of pressure and engine running a bit rough.

Discussion in 'Brakes' started by ButterFingers, Sep 8, 2018.

  1. ButterFingers

    ButterFingers Active Member

    Hi there,
    I have been using the car fairly frequently and today on my return trip from town , I noticed that I had to use a lot of pressure to stop the car when braking. The brakes were working fine up until then. When stopped it was running a bit rough and not its usual smooth self.
    I opened the bonnet the only change that I could detect was that there was oil traces around the D/S rocker cover from the vent with the flame trap in the line.
    The pipes were all connected to the brake servo unit and in good condition.
    Peter
     
  2. quattro

    quattro Well-Known Member

    Sounds like an air leak in the servo system somewhere. Try taking the brake vacuum hose out of the servo and blocking the end. If the engine ticks over better, the problem is in the servo.
     
    sdibbers and ButterFingers like this.
  3. roverp480

    roverp480 Active Member

    Agree, could be a leak in the pipework or servo itself.
     
    sdibbers likes this.
  4. ButterFingers

    ButterFingers Active Member

    today checked the pipes and did the test recommended by disconnecting the hose, result the engine ran smoother.
    reconnected the hose, put a new small short hose on vacuum unit itself and secured with hose clips, no change, no brake force etc.
    Noticed that if I apply the brake with the engine on tick over, the engine shakes, remove foot from brake and smooth again.
    so it definitely points to a faulty booster unit. It will cost $650 to have it rebuilt and 3 weeks off the road.
    It is going to be a trial, as this in my every day car at the moment and I live out in the country....no bus either :(
    Peter
     
  5. mikecoombs

    mikecoombs Active Member

    Hi peter,
    I think i still have a spare unit and some kits here. I've just bought a place up at Bulahdelah and should get up there this coming weekend. I'm crook at the moment. I could come by and have alook at it as there are a few cheaper fixes than a complete rebuild. I'll see what i have as i could post one up and you could just do a change over while yours is repaired.
    Michael
     
    ButterFingers likes this.
  6. ButterFingers

    ButterFingers Active Member

    Hi Mike,
    Thank you for the kind offer, that would be great.
    Peter
     
  7. ButterFingers

    ButterFingers Active Member

    Yesterday I stripped a spare servo unit that I had. It did not take very long.
    There is virtually nothing inside , just the large rubber diaphragm and an enormous spring.
    All the rubber parts were in good condition too.
    There was a lot of hydraulic oil in the container , so the seals on the plunger must have been leaking.
    I was amazed at what a simple construction it is.
    I too then puzzled at how air could leak in or out and found nothing to blame?
    Having checked my faulty booster, I am at a loss as to where the air leak is?
    Peter
     
  8. roverp480

    roverp480 Active Member

    Did you check the air valve seals, air could be passing straight through the whole thing rather than past the diaphragm ?
     
  9. ButterFingers

    ButterFingers Active Member

    do you mean the white air valve device on the top of the servo?
    Peter
     
  10. roverp480

    roverp480 Active Member

    Yes. Just to add a little extra. with brakes off and engine running there is a vacuum on both sides of the diaphragm, the spring pushing it to one end. Then braking, the air valve is opened allowing air into one side which pushes it with the hydraulic cylinder, adding to the braking effort. If the valve isn't sealing, air is entering all the time and thus no vacuum.
     
    Last edited: Sep 11, 2018
    ButterFingers likes this.
  11. mikecoombs

    mikecoombs Active Member

    that is the main cheaper fix I was thinking of. I'm afraid i'm still not well enough to travel but I will get into the storage and see what i can post up.
    there are two valves on the same shaft one either side of the white plastic disc, passing through the middle of it. Normally it is the lower one(s) that go. Do you have the manual? It is explained in 70.50.01, You can do it in the car, just beware of the springs when dissassembling. You probably won't need to remove more than the plastic bits but I have all the gaskets (and the seals) if you do.
     
    ButterFingers likes this.
  12. ButterFingers

    ButterFingers Active Member

    hi Mike,
    get well soon...
    I have a reconditioned servo in the post from Winns. They sell kits of all the parts needed to recondition a servo, and I almost bought the kit, but Geoff, the owner of Winns, advised me that the kits have a reputation for not working and that the only way to be sure was to buy the complete refurbished servo that he sells, that has been sleeved in S/S .
    So that is the option that I have gone for.
    I completely striped a spare servo unit that I had, to see how it all worked and went together.
    The most difficult part to remove was the metal air valve directly beneath the white plastic upper air valve.
    I eventually got it out by using CRC rust remover and air and tapping upside down on the bench, (every force has and equal and opposite force theory) o_O
    It was just very stiff inside the bore, the rubber seal holding it in very well.
    To do that job without removing the complete unit would be almost impossible.
    Peter
     

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