[Healeys] brake servo hiss

Bob Spidell bspidell at comcast.net
Fri Aug 1 10:48:23 MDT 2014


You have a snake in your servo (sorry, couldn't resist). 

When you apply the brakes, a 'slave' cylinder in the servo moves a T-valve and lets atmospheric pressure into the big vacuum canister (it holds vacuum when brakes aren't applied). A 'hiss' may be normal and you just haven't heard it before; or maybe air flow is being restricted on the intake side (which should have a small filter on it, though I think some older servos don't). My booster makes a slight popping sound when brakes applied, but works fine. 

Bob 

----- Original Message -----



Hello, 
B 
My wife and I went for a long drive last night had a great time car ran fair 
...(still running rich with a miss at idle)................anyway when I 
pulled into the garage I could hear a hissB like an air leak.....when I 
applied the brakes...........I never noticed this sound before...........so 
now what!B B B what should I look at (brake servo??)B how to trouble 
shoot,etc.B B Any help would be gratefully acceptedB B 
....................1966 BJ8B ....the servo was rebuiltB so says the PO. 
B 
B 
Mitch 
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