Haven't done much troubleshooting yet but figured I throw the issue out here anyway. I recently finished rebuilding/replacing the brake system on my Mark 2. Drove out of the driveway and after a few taps realized brakes were not releasing. The work completed to date includes new master, new lokeed booster, wilwood front upgrade, rear cylinder/handbrake refurbishment, and some new lines. Had to crack a line coming out of the booster to release pressure to get it back in the driveway. Thanks for any two cents in advance.

John

 

If Auto check the anti creep valve & circuit.

Can also be the servo. Sticking/tight main vacuum piston seals or air valve sticking.

Good luck!

 

Last night we did some more troubleshooting and when we removed the vacuum hose no locking so definitely something with the booster. I might put the original booster back in as it may be fine.

 

Funny ~ when I got up this morning I was thinking about it & was going to suggest you pull the vacuum hose but you beat me to it.

 

Good News! Removed the Lockeed booster and replaced with one of the original units I had, bled the systems and I now have functioning brakes that don't lock up on their own. Guess the old saying if it aint broke dint fix it rings true again. I may send out another original unit I have to be rebuilt at some point. Test drive planned after work.

Thanks
John

 

 

Good news! Damn servos/boosters.

 

The old booster failed too. Expecting a new refurbished unit in the mail today from XKs unlimited. Ordered a new reservac valve as well. Going to take the opportunity to replace the last few lines I hadn't previously as well.

Found another related post on the Jaguar Enthusiasts forum as well: https://jec.org.uk/forums/viewtopic.php?t=6633


Stand by for updates......

 

I presume you are not messing around with Silicone Brake Fluid? It can cause severe elastomer compatibility issues.

 

Nope using synthetic.

 

Please use good old conventional DOT 4 Polyglycol/Polyglycol ether fluid. You are likely causing your own problems with boosters unless the rebuilder/supplier guarantees compatibility of elastomers with fluid. "Synthetic" can mean many things with many different seal swell & other compatibility issues.