Weird booster/vacuum issue

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Ansell
Cadet
Posts: 181
Registered for: 9 years 5 months
Car Make: VW
Car Model: 1997 Golf 3
Location: Somerset West, Cape Town

Weird booster/vacuum issue

Post by Ansell »

Hey ya'll,

Two things:

1 - So for a while now Ive had a really soft brake pedal. It feels like my booster isn't really assisting at all. My brakes work but I have to push the pedal down really hard and far before I get adequate brakes. When I start the car the pedal does drop down a bit, does that mean the booster is working? Could I have a vacuum leak? Could it be my booster? I haven't replaced my pads and drums in a while, could it be that?

2 - Today while my car was idling i pump the brakes a bit and i noticed my rpm rose and then when i stopped they dropped quite low and then came up and stabalized. Like i could hear the rise and fall and then stabalization of the idle. Is this a vacuum issue?

Thanks thanks!
Current:
1997 Golf MK3 GSX (1.8 MP9)

Specs:
79.7kw at 5209rpm and 160nm at 4240rpm (Saichs Dyno)

Modifications:
Stock exhaust with one 50mm-57mm freeflow box.
Standard airbox
Standard cam

Ex: 1970 Beetle 1300 twin-port


If you don't look back at your car after you park it, then you own the wrong car.
VAG Fan
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Posts: 1440
Registered for: 8 years
Location: Pretoria

Re: Weird booster/vacuum issue

Post by VAG Fan »

Regarding 2:
Pumping the brakes always introduces some unmetered air into the engine via the booster. This can destabilise the idle to some extent, yes. I'm not sure what is normal for your engine, though.
Mark R.
- - - - - - - - - -
2004 VW Golf TDI, type 1J, AHF, 317k (2016-current) --- daily
1990 VW Fox, type 16, HM, 304k (2005-current) --- spare runaround
Previous:
1992 Audi 500 SE, type C4, AAR (2001-2020) --- nice while it lasted
1983 VW Golf GTS, type 17, FR (1992-2005) --- most fun car I've ever had
1978 Audi 100 GLS 5E, type 43, WC (1991-92) --- died in the side of a Rekord who cut me off
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EX-DOHCTOR
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Car Model: 2014 Jetta 6 TDi DSG.
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Location: Bryanston, Johannesburg
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Re: Weird booster/vacuum issue

Post by EX-DOHCTOR »

When is the last time you flushed and replaced brake fluid?
2014 - VW Jetta 6 - 1.6 TDi DSG
2000 - VW Golf 3.5 Cabrio - 2.0
1980 - VW MK1 GT - 1.8 Carb - https://www.vwclub.co.za/forum/viewtopi ... 1&t=153861
1971 - Mitsubishi Colt 1100F - https://www.vwclub.co.za/forum/viewtopi ... 1&t=220503
MK1 Build Register: https://www.vwclub.co.za/forum/viewtopi ... 1&t=192835
Instagram: https://www.instagram.com/projectkirschwasser/

Racing is meant for the RACE track - deal with it...
User avatar
Ansell
Cadet
Posts: 181
Registered for: 9 years 5 months
Car Make: VW
Car Model: 1997 Golf 3
Location: Somerset West, Cape Town

Re: Weird booster/vacuum issue

Post by Ansell »

VAG Fan wrote:Regarding 2:
Pumping the brakes always introduces some unmetered air into the engine via the booster. This can destabilise the idle to some extent, yes. I'm not sure what is normal for your engine, though.
This makes me feel better then. Its probably normal. Thanks!
Current:
1997 Golf MK3 GSX (1.8 MP9)

Specs:
79.7kw at 5209rpm and 160nm at 4240rpm (Saichs Dyno)

Modifications:
Stock exhaust with one 50mm-57mm freeflow box.
Standard airbox
Standard cam

Ex: 1970 Beetle 1300 twin-port


If you don't look back at your car after you park it, then you own the wrong car.
User avatar
Ansell
Cadet
Posts: 181
Registered for: 9 years 5 months
Car Make: VW
Car Model: 1997 Golf 3
Location: Somerset West, Cape Town

Re: Weird booster/vacuum issue

Post by Ansell »

EX-DOHCTOR wrote:When is the last time you flushed and replaced brake fluid?
Its been a couple of years, maybe like 4 years, could be even more. It was my moms car and she bought it in 2012 and i got it in 2014. I think ill give that a go. Ive been wanting to do it to be honest but never got around to it. Any idea which fluid i must use? DOT3 or DOT4?

Ill let you know if it sorts out the issue.

Thanks!
Current:
1997 Golf MK3 GSX (1.8 MP9)

Specs:
79.7kw at 5209rpm and 160nm at 4240rpm (Saichs Dyno)

Modifications:
Stock exhaust with one 50mm-57mm freeflow box.
Standard airbox
Standard cam

Ex: 1970 Beetle 1300 twin-port


If you don't look back at your car after you park it, then you own the wrong car.
User avatar
EX-DOHCTOR
Field Marshal
Posts: 13737
Registered for: 19 years 3 months
Car Make: VW
Car Model: 2014 Jetta 6 TDi DSG.
Membership No: 712
Location: Bryanston, Johannesburg
Contact:

Re: Weird booster/vacuum issue

Post by EX-DOHCTOR »

Use Dot 4 Brake fluid.
2014 - VW Jetta 6 - 1.6 TDi DSG
2000 - VW Golf 3.5 Cabrio - 2.0
1980 - VW MK1 GT - 1.8 Carb - https://www.vwclub.co.za/forum/viewtopi ... 1&t=153861
1971 - Mitsubishi Colt 1100F - https://www.vwclub.co.za/forum/viewtopi ... 1&t=220503
MK1 Build Register: https://www.vwclub.co.za/forum/viewtopi ... 1&t=192835
Instagram: https://www.instagram.com/projectkirschwasser/

Racing is meant for the RACE track - deal with it...
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