Mo Murphy Posted April 10, 2013 Share Posted April 10, 2013 I've a spot of bother with my brakes. Braking results in a hard pedal without much braking. Lack of servo assistance methinks and indeed the brake pedal does not sink on starting the engine. The vacuum pump has a nice sharp suck on the skin of my thumb on tick over so I assume thats OK. What else am I looking for Gents, how to test the remaining parts and suggestions. TIA Mo Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted April 10, 2013 Share Posted April 10, 2013 I believe the servos are known for cracking around where the master cylinder mounts, might be worth checking that. Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted April 10, 2013 Share Posted April 10, 2013 IIRC the servo has a diaphram in (similar to the one in the injector pump) it coukd be split or maybe the pipe from the vac pump to servo split. Quote Link to comment Share on other sites More sharing options...
Tanuki Posted April 10, 2013 Share Posted April 10, 2013 Yes, the servo-casing can crack, then all the "suck" produced by the vac-pump goes to waste. The test is: with the engine stopped, pump the brake-pedal vigorously 6 or 8 times to exhaust any retained vacuum from the servo. Then, with a light pressure on the pedal, start the engine. If the servo is servo-ing, the pedal should go down as the vacuum from the engine builds up. If the pedal goes down, switch the engine off, wait 30 seconds and release the pedal. Then apply pressure to the pedal again. If it feels 'harder' than before then the vacuum's all escaped! Note-for-reference: it takes me about 20 minutes to replace a Defender servo. No need to break the hydraulics/bleed the brakes if you know what to do. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted April 10, 2013 Author Share Posted April 10, 2013 Tanuki, there's no movement at all on the pedal on starting the engine. Mo Quote Link to comment Share on other sites More sharing options...
Tanuki Posted April 10, 2013 Share Posted April 10, 2013 Tanuki, there's no movement at all on the pedal on starting the engine.Mo If the pedal's hard with the engine not-running and doesn't get lighter when the engine is running it all points to the servo truly not fulfilling its servoing-duties. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted April 11, 2013 Author Share Posted April 11, 2013 Well, I've got a replacement non return valve coming tomorrow, if that doesn't fix it then it'll be new servo time by the looks of things. Mo Quote Link to comment Share on other sites More sharing options...
Baz2236 Posted April 11, 2013 Share Posted April 11, 2013 I have a similar problem but when I turn the engine off I can hear the hissing like a kettle which is the vacum escaping. I have pull the master cylinder off and the rubber on servo is split and perished if I wobble the rod you can her the hiss. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted April 18, 2013 Author Share Posted April 18, 2013 Just to update, the non return valve made no difference so I had to bite the bullet and replace the servo. Normal service resumed Mo Quote Link to comment Share on other sites More sharing options...
Baz2236 Posted April 18, 2013 Share Posted April 18, 2013 My brakes were very hard and also this hissing noise i have replaced the servo yesterday and my god what a difference that makes just the lightest touch on the pedal stop me now. Baz Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted April 18, 2013 Author Share Posted April 18, 2013 Glad to see you've sorted it too, Baz. Mo Quote Link to comment Share on other sites More sharing options...
discomikey Posted April 18, 2013 Share Posted April 18, 2013 if you can get hold of a vaccum tester and gauge (basically its a pump with a gauge on it, and it sucks, and you then watch the gauge for excessive leakyness Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted April 18, 2013 Author Share Posted April 18, 2013 Would it cost more than a new servo Mikey ? Mo Quote Link to comment Share on other sites More sharing options...
Yostumpy Posted April 19, 2013 Share Posted April 19, 2013 Out of interest where did you get your servo from, and how much., Mine has 2 cracks, but have put gaffer tape on them (6 months ago) and works a treat, not sure the MOT man will think so tho' in 6 weeks time. Quote Link to comment Share on other sites More sharing options...
Baz2236 Posted April 19, 2013 Share Posted April 19, 2013 I got mine fro. Lrdirect for £70 quid if I know it would improve that much I would of brought one ages ago. Quote Link to comment Share on other sites More sharing options...
Dave_SFX Posted April 23, 2013 Share Posted April 23, 2013 I've had a very similar problem with my brakes - did the servo and master cylinder and they worked great for a couple of months but now brakes are near non-existent. Tried the test above to ascertain servo's servoiness with very poor results. No cracks around master cylinder joint, any other hot spots to have a look at? Is there a way to test the servo on it's own to show it has failed? I'm thinking 2-3 months is certainly within warranty... Quote Link to comment Share on other sites More sharing options...
cackshifter Posted April 23, 2013 Share Posted April 23, 2013 Can you measure the vacuum? Should be about 0.8 bar. The EGR valve connection is a handy place to attach a gauge. Quote Link to comment Share on other sites More sharing options...
Baz2236 Posted April 24, 2013 Share Posted April 24, 2013 After fittibg my servo this weekend I only have good brake on the first press of the pedal every time I press pedal after that the effective ness of the brake is reduced and the pedal gets harder. I have swap the vac pump and same surely my servo should do better then that. Quote Link to comment Share on other sites More sharing options...
Baz2236 Posted April 24, 2013 Share Posted April 24, 2013 After fittibg my servo this weekend I only have good brake on the first press of the pedal every time I press pedal after that the effective ness of the brake is reduced and the pedal gets harder. I have swap the vac pump and same surely my servo should do better then that. Quote Link to comment Share on other sites More sharing options...
Baz2236 Posted April 24, 2013 Share Posted April 24, 2013 After fittibg my servo this weekend I only have good brake on the first press of the pedal every time I press pedal after that the effective ness of the brake is reduced and the pedal gets harder. I have swap the vac pump and same surely my servo should do better then that. Quote Link to comment Share on other sites More sharing options...
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