Dusty
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| posted on 16/2/12 at 07:36 PM |
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Polo brakes.
Just bought a 10 year old polo saloon two weeks ago. It's been fine till today when the brakes scared me. Most of the time the pedal is softish,
going perhaps 1.5 inches, responsive, progressive and the brakes work a treat. Starting on a slope today I nearly hit the car in front as the pedal
was hard, dead and the brakes were almost non existent. Another 100 yards and they were fine again but if I brake twice in succession the brake gets
more wooden and less effective. Almost as if the servo is exhausted by one operation.
Its a 1.9 diesel and my first oil burner. Do they have servos? Is this a known problem? Anyone any ideas?
Oh, and my airbag light is on too!
[Edited on 16/2/12 by Dusty]
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Ninehigh
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| posted on 16/2/12 at 07:50 PM |
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Ah is this the same thing as when you pump the brakes with the engine off... It gets harder and harder, but if you just keep the pressure on then it
slowly goes down..
Vacuum something? It's some part called vacuum something
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martymcfly
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| posted on 16/2/12 at 08:05 PM |
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Faulty vacuum pump?
Not sure on the VAG set up, sometimes mounted on the cam end and sometimes as part of the alternator iirc. Could also be a leaking vacuum hose between
the pump and the servo.
Pump might look something like this i guess
VW GOLF MK4 BORA POLO 1.9 TDI SDI **GENUINE** VACUUM PUMP | eBay
[Edited on 16/2/12 by martymcfly]
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rusty nuts
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| posted on 16/2/12 at 08:18 PM |
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It's either the brake pump, servo , or brake pump .Remove the one way valve from the servo , start the engine and block the valve with your
thumb, you should feel a vacuum. To test the servo pump the brake pedal without the engine running, hold the pedal down and start the engine, the
pedal should go down. Older petrol engined VWs had a rubber connecting hose on the servo pipe that often split causing exactly the same symptoms you
have, not sure if the diesels have a rubber hose?
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Dusty
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| posted on 16/2/12 at 08:24 PM |
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It is like the wooden feel you get when the engine is stopped and you try the brakes till the servo is exhausted but while driving it recovers but
doesn't seem to have any reserve. One shot and it's done. Is that whatyou would get with a leak in the system? So pump is down on
efficiency to almost zero or I have a hose leak or servo diaphragm leak.
Just had a look and nothing obvious but there are two small rubber hoses also come off the servo pipe and both seem a bit old and loose. They are that
special braided rubber that VW do which always splits at the ends after a couple of years.
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Dusty
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| posted on 17/2/12 at 01:05 PM |
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Found a leak. One of the small hoses that comes off the main pump to servo hose was split and off at the other end. Sealed and brakes back to normal.
Pump is sucking well and servo doesn't leak. I think I caused the leak when doing maintenance.
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