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  1. #21
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    Spotted this on Vec C...

    To test the vacuum - pump the brake pedal until it's rock solid with the engine switched off, and then while you maintain pressure, start the engine and the pedal should sink away. This will show that the vacuum is getting to the servo.

    Does this apply to the brake vacuum pump

  2. #22
    VXR enough Jon1796's Avatar
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    It’ll show vacuum is getting to servo,which it is as it works most off the time, not that you have a leak !!!

  3. #23
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    Quote Originally Posted by Jon1796 View Post
    It’ll show vacuum is getting to servo,which it is as it works most off the time, not that you have a leak !!!
    I'm not too worried if I have a leak as that can be fixed without major trouble, what I'm more worried about is that the vacuum pump isn't working. I followed the advice on the previous post and heard nothing, so does this mean my pump is faulty or that the fact that I didn't hear anything means it's working?
    Last edited by sinbrad; 8th December 2018 at 08:27 PM.

  4. #24
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    It should still return the pedal I believe just at ignition when everything is getting electric passed through. If that pedal is rock hard or you have a leak the vac pump would be running constantly like it did for me until it builds the vacuum. If you have nothing making a sound when pumping that pedal hard then maybe the pump / fuse has packed in.

    One thing to check is that valve on the pic you posted, the one with the brown plug. I believe that's a vacuum sensor. With mine unplugged the vacuum pump doesnt kick in.

    Disconnect that plug and just make sure all the contacts are clean then reconnect it / give it a bit of a tap aswell, can't hurt.

    These are just ideas from my experience with the car. Without seeing yours it's hard to tell.
    Last edited by mikez1; 8th December 2018 at 08:33 PM.

  5. #25
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    Quote Originally Posted by mikez1 View Post
    It should still return the pedal I believe just at ignition when everything is getting electric passed through. If that pedal is rock hard or you have a leak the vac pump would be running constantly like it did for me until it builds the vacuum. If you have nothing making a sound when pumping that pedal hard then maybe the pump has packed in.

    One thing to check is that valve on the pic you posted, the one with the brown plug. I believe that's a vacuum sensor. With mine unplugged the vacuum pump doesnt kick in.

    Disconnect that plug and just make sure all the contacts are clean then reconnect it.

    These are just ideas from my experience with the car. Without seeing yours it's hard to tell.
    Thanks for that. Unfortunately I'm off on holiday early tomorrow so won't get another look and test until I return but that'll be the first thing I check.

  6. #26
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    Well, followed some advice from my other thread re the brake test report and I've managed to replicate the hard brake pedal. If I take the car out and drive in a normal manner i.e. don't put the foot to the floor then the car behaves as it should. However, if I give it some hard acceleration then once I then put my foot on the brake it gives me the hard pedal. I was testing out the bed in method by accelerating to around 70mpm and then braking and repeating this. It does this every time but driving normally the brake works as it should. So the problem is related to hard acceleration and or the swift braking?

  7. #27
    VXR enough Jon1796's Avatar
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    Same as turn on engine don’t touch brake pedal, let her build up vacuum for minute or two turn off. Then pump brake a few times will go hard.
    Servos ran out off puff/vacuum.
    So it’s knackered, got a leak, or dodge one way valves.


    Sent from my iPhone using Tapatalk

  8. #28
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    Silicone hose and new one way valves....

    Did you say if the vacuum pump goes off? I've not read back but I recall you saying you didn't hear it.

    To test the vac pump fully without even messing with brake pedal, turn key to ignition then just disconnect the joint in the pipe at the back of the engine bay just above the brake servo (pretty much straight back from the power steering reservoir). It should let out a hiss as the pressure releases and the vac pump should start going continuously. If there's no sound then you have no pressure and if the vac pump doesn't go off either then it's possibly knackered too.

  9. #29
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    Quote Originally Posted by mikez1 View Post
    Silicone hose and new one way valves....

    Did you say if the vacuum pump goes off? I've not read back but I recall you saying you didn't hear it.

    To test the vac pump fully without even messing with brake pedal, turn key to ignition then just disconnect the joint in the pipe at the back of the engine bay just above the brake servo (pretty much straight back from the power steering reservoir). It should let out a hiss as the pressure releases and the vac pump should start going continuously. If there's no sound then you have no pressure and if the vac pump doesn't go off either then it's possibly knackered too.
    That sounds an easier test and will try it out tomorrow or Monday as away all day tomorrow and finish early on Monday

  10. #30
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    Quote Originally Posted by Jon1796 View Post
    Same as turn on engine don’t touch brake pedal, let her build up vacuum for minute or two turn off. Then pump brake a few times will go hard.
    Servos ran out off puff/vacuum.
    So it’s knackered, got a leak, or dodge one way valves.


    Sent from my iPhone using Tapatalk
    Doesn't the pedal go sort of hard anyway when pumping with the engine off, thought that was a result anyway as it's part of bleeding brakes? So what am I actually looking for if servo is working, will the pedal not go hard?

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