(Another) brake question
Hi,
My G failed its MOT on the brakes. It has had new wheel cylinders, calipers. pads and brakelines. The tester failed it on: brakepedal very slowly sinking when depressed and has told me it is the servo that is at fault. Before I change this (very expensive!) what are your thoughts?
The last time I had a servo go bad on me the pedal was rock hard :roll:
The G seems to be braking fine but I obviously need this sorting or it won't pass its test.
THanks in advance
Regards
Richard
That does'nt make sense.
More likely the master cylinder. I believe you can get repair kits from MB but I would go for a complete new one.
check the slave cylider as well
If the pedal goes down, then you are looking at brake Master cylinder fault.
Servo would not do this, you would have a hard pedal with difficult braking and you would be exerting more force on the brake pedal to achieve braking.
Regards,
Servos tend to work or not. Sinking pedal is external leak or internal leak inside master cylinder.
To test servo... stop engine... give pedal 5 pump to exhaust servo vacuum reservoir. Then with foot on pedal for medium brake pressure restart the engine. It should feel as if the pedal is falling away from you (as boost amplifies your input).
If you get sinking pedal when holding after the 5 pumps to exhaust servo with engine off .. you have proved it is beyond the servo (ie external leak or internal leak on master cylinder) as you have effectively taken the servo out of the equation by your 5 pumps.
I have only had one servo fail, ( not on a G) it hissed like a snake. I reckon MOT man means Master Cylinder. Incidently is it only the 463 that has extra reserve (capacity) for the Brake servo?
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Gentlemen,
thank youf for your input. I will get them to change the master cylinder. Is this a dealer only part or can I get it cheaper from the motorfactors?
Is it the same as the Merc vans because I have acces to loads of them....
THanks again
Richard