My 1997 Discovery XD can't brake after I changed the brake master cylinder. I put a brand new brake master cylinder on, but after the complete bleeding and I started the engine I found the brake pedal didn't travel down as much as before, also the braking had no power and it took a fair long distance to fully stop the truck. With the hood open, I can hear a hissing noise from the brake reservo area when someone stepping the brake pedal. The engine became running rough after this,and now the check engine light went on with the codes P0300 and P1316.

It seems to me something is wrong with the brake booster or the vacuum line to it.

Can someone guide me on how to check the brake booster on a Disco 1? and how to disconnect the vacuum to the booster and replace it if needed?

 

Is there a check valve on the booster? Check that too....