hissing under dash

[daddyfixit]

problem;  A constant hissing under dashboard from brake servo; touch pedal and it goes away till you next brake ? 
I took car for new clutch this morning, got there and he had to rebook me.  So driving in traffic and The brake pedal went rock hard (no servo) but I kept trying brakes for rest of journey and had no problem.

1. deffo servo failure, but wasn't there an issue were the ends of servo pipe spilt off causing an air leak ??   its an X-reg so I can appreciate it may have split (not looked yet)

but the fact it can be heard inside car bothers me--I know brake pedal linkage to master cylinder is under dash, but what kind of a job is it to change a servo ??

[regw]

I'd say the noise from that area kind of makes sense in that the servo (aka brake booster) is just forward of the pedal.
Just had a quick shufty at the hyenas manual and at least part of the servo can be accessed from inside the cabin when the lower fascia is removed.
the actuator shaft is connected to the pedal lever.
and you have to remove the nuts down there to get it and the master cylinder out of the engine bay.
 
Only inspection will tell but it's possibly a worn leaking servo unit sucking in air or the pipe from the vac pump on the cylinder head is possibly failing at the servo end
(I'm assuming its a deisel)

[daddyfixit]

thanks Regw;

  Yes, its a Pd 90hp model (the baby one !)      But my mrs and kids say there has been a hissing from the brake pedal area for years, which I could not ear as I have tinnitus!
  But on Tuesday it had a new dual-mass & clutch fitted----the car feels, sounds and drives like a new car now but now I can hear the hissing noise. I have noticed that on the 2nd or 3rd application of the brakes, the pedal goes rock hard until you leave it a few seconds then its all ok again ?

I have been reading a post about main servo pipe splitting so I am going to try and have a nose at that when the rain eases off (later this year )

thanks for replying.

[daddyfixit]

hello people;

just let you know it was the servo at fault, got a used one from Cornwall off ebay for £38 !  exact same part number as well.   Got local garage to fit it, ripped me off but kept it 2 days so they could play out how difficult it was to swap.   Its back on the road, awaiting sill repair and then some paintwork getting done.

[Chrispb]

Not the easiest of jobs inside or under the bonnet

[daddyfixit]

Not the easiest of jobs inside or under the bonnet

an R-sole of a job, so I got a garage to do it..who over-charged me and left car covered in oily shite hand prints on seats/dash/doors= everywere !!