Hiss when braking?

Big lumps of metals and spanners. Including servicing and fluids.

Moderators: User administrators, Moderators

Post Reply
Blakefruid
Registered user
Posts: 48
Joined: 13 Feb 2011, 12:13
80-90 Mem No: 12486
Location: Princes Risborough, Buckinghamshire

Hiss when braking?

Post by Blakefruid »

Morning all,
I'm hoping someone can please point me in the right direction.
My brake's aren't great when the bus is first started and after a few hundred yard's when I brake you can hear a hiss coming from the pedal area- more clutch side I would say and definitely not near the master cylinder, it then goes away until I presume pressure has built up again and then hisses again- any ideas?
Cheers Blakie
'88 Club Joker 1.6TD

User avatar
R0B
Moderator
Posts: 18852
Joined: 07 Oct 2005, 17:33
80-90 Mem No: 864
Location: Cheshire

Re: Hiss when braking?

Post by R0B »

I suspect its coming from your brake servo.
2.1 LPG/Petrol Auto Caravelle

"The difference between genius and stupidity is that genius has its limits"

User avatar
Ian Hulley
Registered user
Posts: 12659
Joined: 11 Oct 2005, 08:08
80-90 Mem No: 1323
Location: Wirksworth, Derbyshire ... or at t'mill

Re: Hiss when braking?

Post by Ian Hulley »

R0B wrote:I suspect its coming from your brake servo.

Yes, DEEP joy if it is :|

Ian
The Hulley's Bus
1989 2.1DJ Trampspotter
LPG courtesy of Steve @ Gasure

User avatar
tonytech
Registered user
Posts: 1194
Joined: 11 Oct 2005, 06:40
80-90 Mem No: 477
Location: Liverpool

Re: Hiss when braking?

Post by tonytech »

Unlikely, but, did / does your bus have cruise control? There is a vacuum dump valve fitted to the pedal assembly.
There shouldnt be any vacuum in it normally, but some bright spark may have bodged it in the past.
T
There are 10 kinds of people. those who understand Binary and those who dont

Blakefruid
Registered user
Posts: 48
Joined: 13 Feb 2011, 12:13
80-90 Mem No: 12486
Location: Princes Risborough, Buckinghamshire

Re: Hiss when braking?

Post by Blakefruid »

Hi All,
Thanks for the reply's!
Rob, yeh I thought it might be the servo, so I took the binnacle off and drove about listening, but definitely coming from by my feet and not up top.
Tonytech, the bus had an aftermarket cruse control fitted (never worked!!) when I bought it, so will investigate further.

Could this have anything to do with the clutch master cylinder? just seems to be coming from around the clutch pedal area, but hard to have your head down there when driving and won't hiss when the bus is stationary.
Thanks again,
Blakie
'88 Club Joker 1.6TD

Blakefruid
Registered user
Posts: 48
Joined: 13 Feb 2011, 12:13
80-90 Mem No: 12486
Location: Princes Risborough, Buckinghamshire

Re: Hiss when braking?

Post by Blakefruid »

so finally got the dash out to fix a long list of bits so took the servo out to find it totally brimmed i.e. poured out as soon as I moved it (knew I should have covered the carpet!!!) with black fluid so either a master cylinder leak (never had a low reservoir issue) or the servo is sucking oil from the engine- if that's possible??? i'll trace the pipe tomorrow and see if I can find the one way valve. i'll update when its fixed.
'88 Club Joker 1.6TD

Post Reply