leaking Master cylinder
One of the jobs I've just got around to is changing the brake fluid. I used a pressurised tool to do this. all ok but there is a leak between the reservoir and the master cylinder. It only leaks when the pressure in on, not in normal use. Anyone had this issue? Is there a seal kit available to repair this area?
Thanks for any advice.
The seal has probably hardened with time. There is no pressure on this seal in normal use so if it is not leaking when in use/standing then it was only your pressure bleeding that causes a leak. I might be tempted to pull, polish bore(1000 grit wet n dry) and reseal the master cylinder.. it is the only thing stopping you sometimes! Don't compromise brakes.
I may be wrong but seal kits are no longer available from the dealer but do check. They will need to know what make it is i.e. ATE or ????; you may try ATE suppliers to see if the rubber kits are supplied through them. Often, Mercedes tie up contracts with suppliers that they are unable to sell their specified kits.
There are two bore sizes to the brake master cylinder. Only way to know this is to measure the bore, dismantling from servo.
The cylinder are not cheap and if you decide to replace, please save the old unit for the club unless it is on an exchange price. My proposal is if the club through me (Rakesh) may have your old unit; if I can refurbish this I will do and sell through the club for the club, if they are agreeable.
Ps; What pressure did you bleed at? Maximum bleeding pressure should not exceed 20 - 22 psi.
Good Hunting.
I think he was referring to the two little grommet seals that locate the reservoir onto the master cylinder.
Ah, the reservoir seals. In that case these should be available. I was thinking seal in the master cylinder into servo.
- I must read carefully what is written down!
- I must read carefully what is written down!
- I must read carefully what is written down!
- I must read carefully what is written down!
100. I must read carefully what is written down! 
Oh those seals.. yes you can get them but not very well shown on EPC.. I was doing a blind guess with the storeman; cannot find what I actually ordered written down..
I think there are 2 types..
While you are in there.. if it has a hose.. replace the 6mm hose .. EPC sell it by the meter, The diff lock masters probably already need that hose replacing ;-)
Discussion on here; http://www.gwoa.co.uk/content/460-rhd-clutch-fluid-tank-and-master-cylinder
Anyway .. if that leaks under pressure.. no problems but it does indicate you were using too much presssure so reduce it next time. I prefer the good old foot myself.. uses the system how is was designed to be used.
Yes, rapid pumping of the pedal develops more pressure and helps expel dissolved gasses.
Looks like a few types of Master Cylinder but it only lists the Rubbers to suit one type?
Maybe all the same anyway... all the Petrol & Diesel appear the same..
A000 431 16 49 x2 @ £2.20 each + vat MB Germany have stocks
463 list 2 different types
Thanks very much for all the tips. I was using the pressure system instead of pumping as I had been advised that pushing the piston to the bottom of the cylinder was to be avoided in case a worn bore damages the seals in such an old girl!
I had a read of the articles, I have to say mine looks different, there is no separate reservoir for the diff locks, which don't work, that job is a bit down the line! The diff lock levers don't seem to want to move! I don't have the front propshaft as it was removed to save on fuel economy apparently!
lots to do!
The levers should move irrespective of popshaft present or not. They just operate slave cylinders with an over-centre spring action. Missing diff-lock fluid reservoir may be another one of your issues.
The Diff Lock Reservoir is in the Left Rear of the engine compartment, not anywhere near the Master Cylinders under the levers... Just a simple pipe down the left chassis leg that connects to the twin Master Cylinders with a plastic T piece...
And the diff lock mechanism crank mechanism that operates the slaves (turns the force 90 degrees from vertical to horizontal) will seize, the springs will rust and the clips (same as gearchange ones) rust. So have a peer at that. There is a short length of the 6mm rubber hose that feeds these master cylinders and that perishes.. so then no fluid in the wee reservoir.
Note front prop UJ should be timed so they are out of sync...go search "41.61 propeller shaft pdf"
Thanks for the replies. I've located the diff lock reservoir on the left as you say Gav. I was looking at a pic of a LHD!
I managed to get tthe front diff lock lever up but the rear is proving difficult to budge, more investigations tomorrow. There was nice clean oil in the reservoir.
I'll try to find a suitable front shaft hopefully reasonably priced! It should be a 4WD after all!
I managed to get tthe front diff lock lever up but the rear is proving difficult to budge, more investigations tomorrow. There was nice clean oil in the reservoir.
Not oil.. use brake fluid .. just before you put the wrong stuff in there.
I did meant brake fluid LOL!
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They're the ones Arni, and the pressure was probably 32psi Rakesh, so may have overdone it there