Brake Fluid change problem

[Collapsedsuspension]

Hi all,

We are trying to change the brake fluid on my ABS 16v M59, starting at the back we can't seem to get air out of the system. Valve open, pedal down, splutter air and fluid, close valve, pedal up, repeat ad nauseam. Reservoir is full, but fluid is drawing out of it slowly. Are there seals that are known to go? There are no obvious leaks on the system.
We don't have any one way valves or pressure blessing equipment to help, sadly.
Do we need to do anything with the bias valve in the back? Load up the boot to push down the suspension maybe?

[Gravity]

If fluid is being drawn out of the master cylinder reservoir and the only point of exit is the rear brake you're working on, and fluid is coming out of the bleed nipple, then your efforts are being rewarded. Close the bleed nipple each time just before the down stroke is conpleted.

Just don't press the brake pedal ALL the way down to the floor. In normal braking, this never happens, so you could be pushing the seals past their normal point, which might not do them much good.

[brodfather11]

Do we need to do anything with the bias valve in the back? Load up the boot to push down the suspension maybe?

 I don't think the berlingos with ABS have a bias valve, it would defeat the purpose of the ABS. Its there to stop the rear brakes locking up the rear brakes when lightly loaded. Just like the ABS system.



 The berlingo brakes are notorious for getting to bleed properly

[Collapsedsuspension]

Thanks chaps. I'll try the Lexia bleed facility too.

[jj9]

If you're only changing the fluid and you haven't opened the system to fit any new components and you haven't let the fluid level drop below the minimum the air you are seeing must have always have been there!

As brodfather says the brakes are difficult to bleed, especially the rears, try raising the rear of the vehicle on ramps as high as you can get it.


.

[Gravity]

Or use a pressure bleeding kit,
Is there anywhere near you that will rent one? They're very simple bits of kit. I've had mine for years, and i think it cost me around £40. Helped out a few friends with it, so it has proved its worth..

[polar]

The master cylinder reservoirs are a bit low and the baffle in the reservoir is a bit high and the fluid wont go over the baffle so it empties at the back but the front is full of fluid. You need to get the front of the vehicle higher than the back. If the vehicle is sloping forward you have no chance.

Trust me on this one been there done that!

[jj9]

Yes, you are very correct about the baffle in the master cylinder reservoir, you have to keep it full almost to the brim for it to flow over into the rear section.

.

[Gravity]

Yes, you are very correct about the baffle in the master cylinder reservoir, you have to keep it full almost to the brim for it to flow over into the rear section.

Good to know that. Thanks. Never done a brake fluid change on a M59 before - that joy is coming up this week.
That's where a pressure bleeding setup is good - it doesn't matter where the internal baffle is in the reservoir, because the kit gives a constant supply of its own brake fluid.

[lorraine]

Mine is an 04.i have never changed the brake fliud,i also have a 1995 mercedes that i have never changed the fliud on either.Its such a pig job if it aint broken dont fix it,works for me.