brake servo hissing

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geoff
Posts: 123
Joined: Tue Jan 31, 2012 1:19 pm
Your car is a: 1982 Spider

brake servo hissing

Post by geoff »

I have just started hearing a hissing sound from where the brake pedal rod enters the servo. This is accompanied by a hestitating of the engine.
Are we talking about the need of replacing the servo ?
regards
geoff
rridge
Posts: 162
Joined: Thu Aug 10, 2006 11:59 am
Your car is a: 1981 Turbo Spider

Re: brake servo hissing

Post by rridge »

Diagnosis by part replacement is particularly inconvenient on the brake booster. Two other air leak suspects are the check valve on the front of the booster where the vacuum hose connects and the vacuum hose itself. Put a helper in the driver's seat while you get your ear closer to the booster while the brake pedal is depressed. But yes, the rubber diaphragms inside the booster housing have a finite life.
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courtenay
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Posts: 1321
Joined: Mon Nov 30, 2009 11:41 pm
Your car is a: 1980 Spider 2000
Location: Courtenay, BC, Canada

Re: brake servo hissing

Post by courtenay »

geoff wrote:I have just started hearing a hissing sound from where the brake pedal rod enters the servo. This is accompanied by a hestitating of the engine.
Are we talking about the need of replacing the servo ?
regards
geoff
Yes. Use vise grips to Pinch the vacuum hose leading to the booster. Then put your foot on the brake. If no whoosh and no change in idle, the unit is pooched. See my booster replacement thread in the General Maintenance section.

http://www.fiatspider.com/f15/viewtopic.php?f=9&t=39014
Bruce Shearer
'80 Spider Fi
'10 Volvo XC70
'06 GMC 1 Ton PU
'72 Spider a long, long time ago
SteinOnkel
Posts: 1000
Joined: Tue Feb 19, 2019 9:31 pm
Your car is a: 1978 124 Spider 1800

Re: brake servo hissing

Post by SteinOnkel »

Text book example of vacuum leak at brake booster.

Enjoy. It's a pita to replace, just like everything else on these cars.
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