Good day to you all.
My 1998 XKR failed it's MOT this morning as the brake servo isn't holding a vacuum. I suspect the brake servo check valve is passing, but to be sure, I have ordered a Mityvac hand vacuum tester so I can do some diagnosis.
My question is, how difficult is it to remove the check valve? Would fitting an inline check valve suffice?
Regards
Colin

 

I see you are getting a vacuum pump. That will help in determining the condition of the brake booster diaphragm. Attached is a shot of the non return valve location. And a shot of the component locations. I assume yours is RHD making removal even easier. The booster hose attaches to the right side of the throttle body. If the booster checks out as good then SNGBarratt stocks the correct hose and return valve. They are one assembly.

 

Thanks avern1 for the diagrams and information. I've just pulled the check valve from the servo and tested it. It allows air one way but not the other so appears to be functioning correctly. I've greased up the grommet and refitted the valve. I was rather hoping the valve was passing so I'll have to wait for the vacuum testing tool to arrive. Hopefully the problem isn't an internal servo leak but I'm not confident. Does anyone know if there are kits for repairing the servos?
Regards
Colin

 

Just had the same problem on my Stype with the same powertrain as my XK8. Hoped it woulld be check valve but it wasn't. Had ro replace the servo, there are rebuilders that cna do some servos but not all. Turned out mine had rusted out. Fortumately not terrible to change.

 

My mityvac vacuum tester turned up today and I've confirmed that the brake booster isn't holding a vacuum, more's the pity. I've managed to find a NEW, old stock, booster with master cylinder for an XJ8. Only £150. Ebay, should arrive in a week. I'll have to do some slight modifications as mine I believe is a 3 bolt mount, the new one will be 4 bolt mount. I will take photos and document how I get on. The mityvac is a 8550 model with adaptors and a bottle for bleeding brakes. Looking forward to using it... It'll be a few days before I start as I'm just out of hospital after a wee operation. Have some motorbikes to fix first. Fun, fun, fun.😀