big ives Posted September 9 Share Posted September 9 Factory Defender V8 CSW 1989 Just past MOT last week Only just started yesterday twice my brake pedal got spongy giving the impression no vacuum at the servo had to push the pedal to the floor to get her to stop then the pedal got hard again Only happened two times yesterday doing about a 140 mile drive. Already checked the following this morning: - Hose to servo good vacuum no leaks and relatively new hose. Pump brake pedal start engine pedal moves a little bit as normal. No brake fluid leaks no loss of fluid. All callipers rebuild over a year ago. All wheel bearings checked no play. Spin the wheels and all brakes operate (no engine running) Also looking I have a G valve going to the rear wheels not a bias valve. Can not see or detect/hear any leak at the servo pretty hard with the v8 running. So, is my brake servo on the way out? Any other checks I can do to the servo? Brake master cylinder? Also does anyone have the part number for this G valve? Can this G valve be replaced with the normal defender bias valve? As always many thanks Ivan Quote Link to comment Share on other sites More sharing options...
big ives Posted September 9 Author Share Posted September 9 Factory Defender V8 CSW 1989 Just past MOT last week Only just started yesterday twice my brake pedal got spongy giving the impression no vacuum at the servo had to push the pedal to the floor to get her to stop then the pedal got hard again Only happened two times yesterday doing about a 140 mile drive. Already checked the following this morning: - Hose to servo good vacuum no leaks and relatively new hose. Pump brake pedal start engine pedal moves a little bit as normal. No brake fluid leaks no loss of fluid. All callipers rebuild over a year ago. All wheel bearings checked no play. Spin the wheels and all brakes operate (no engine running) Also looking I have a G valve going to the rear wheels not a bias valve. Can not see or detect/hear any leak at the servo pretty hard with the v8 running. So, is my brake servo on the way out? Any other checks I can do to the servo? Brake master cylinder? Also does anyone have the part number for this G valve? Can this G valve be replaced with the normal defender bias valve? As always many thanks Ivan just found this part number for the G valve NRC 8215 so i belive this is the correct part Quote Link to comment Share on other sites More sharing options...
fmmv Posted September 9 Share Posted September 9 My experience of loss of vacuum or servo assistance is the pedal goes very hard, you need a colossal push. So if yours is springy, or goes roght down, I would wonder if it was more to do with hydraulics, air getting in perhaps or maybe master cylinder going bad? 1 Quote Link to comment Share on other sites More sharing options...
steve b Posted September 9 Share Posted September 9 1 hour ago, fmmv said: My experience of loss of vacuum or servo assistance is the pedal goes very hard, you need a colossal push. So if yours is springy, or goes roght down, I would wonder if it was more to do with hydraulics, air getting in perhaps or maybe master cylinder going bad? I would agree with this. Unbolt the MC from the servo can and inspect the piston end and bore for fluid. No pipes need to be disconnected to do this and with a small G clamp the piston can be pushed in to see more bore. Drum or disc on the back? Steve Quote Link to comment Share on other sites More sharing options...
big ives Posted September 10 Author Share Posted September 10 Sorry for the late response travelling back to work Ok I will look at the master cylinder maybe time to replace it looks like it been on from the factory in 1989👍 For sure not leaking, no fluid in the drivers footwell But better to replace Many thanks Ivan Quote Link to comment Share on other sites More sharing options...
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