Brakes Series 1 3.8 original

Technical advice Q&A

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Womanofstraw
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Joined: Sat Apr 23, 2022 4:45 pm
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#1 Brakes Series 1 3.8 original

Post by Womanofstraw » Sat Apr 23, 2022 4:51 pm

Advice needed -

Brakes working great when engine is not running but when engine is running brakes stay in after pedal is pressed.

I know my way around a car but stumped.

Thanks :roll: :swerve: WOS

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DWW
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#2 Re: Brakes Series 1 3.8 original

Post by DWW » Sat Apr 23, 2022 5:35 pm

Not an expert but sounds like it is something to do with the servo or vacuum lines.
Danny

1962 S1 3.8 FHC (1012/1798)
2015 Range Rover Sport SVR
"Experience is something you don't get until just after you need it."

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abowie
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#3 Re: Brakes Series 1 3.8 original

Post by abowie » Sat Apr 23, 2022 10:31 pm

Without the car in front of me my best (not really that good) guess would be that you have vacuum to the booster going the whole time.

You could start by disconnecting the vacuum line from the top of the Kelsey Hayes booster and see if this changes things. The car can be driven safely without brake boost.

Then check the air valve assembly 6 isn't jammed and that it is not being actuated with the brakes off. There is a lever on an eccentric that should be just clear of the valve with the brakes off.

Image

Also check if the check valve c14693 on the Reservac tank is working.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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mgcjag
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#4 Re: Brakes Series 1 3.8 original

Post by mgcjag » Sun Apr 24, 2022 7:34 am

The service manual has a fault chart for the Kelsey servo and describes checking/setting the valves....Steve
Steve
69 S2 2+2 (just sold) ..Realm C type replica, 1960 xk150fhc

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abowie
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#5 Re: Brakes Series 1 3.8 original

Post by abowie » Sun Apr 24, 2022 8:38 am

mgcjag wrote:
Sun Apr 24, 2022 7:34 am
The service manual has a fault chart for the Kelsey servo and describes checking/setting the valves....Steve
I didn't know that. Excellent.

We did 165km in my E Types today on the monthly "Exercise Class" run.
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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