Club 80-90 Forums

I'm about to replace the brake fluid on the van. Anyone know how much is required to refill the system following a complete drain?
Cheers

The factory repair manual says that you need to bleed 0.5 litres of fluid on each bleeder to have new fluid in all the lines.

Cheers Z. Out of interest when you say factory manual - is that the Bentley? I'm pretty sure theres no mention of it in Haynes.

From memory...something like 1.1 - 1.2 litres which includes bleeding the clutch.

Furthest away first (so for a R/H/D that's the nearside rear)

The correct way to bleed (although most people don't bother) is to use something like a Turkey Baster and suck out the majority of the OLD brake fluid from the reservoir and then top up with new fluid BEFORE you start.
Think of it this way...if you don't do this.. the FIRST wheel cylinder and brake line just gets bled with old contaminated fluid....personally, I always revisit the first bleed point AGAIN at the end and take another 100ml or so to ensure the whole system contains new fluid.
Remember....it isn't what it looks like...nice clear fluid can be contaminated with water if your van was left standing for several years....brake fluid is hygroscopic (attracts moisture from the surrounding air) just 3% contamination can lower the boiling point of the brake fluid by nearly 100C and with brakes, that is very bad news.

Martin

chuggers72 wrote:Cheers Z. Out of interest when you say factory manual - is that the Bentley? I'm pretty sure theres no mention of it in Haynes.

Here:
http://vwt3.hu/files/egyeb/Fahrwerk.pdf" onclick="window.open(this.href);return false;

No Bentley, altough I think it was written based on these german factory repair manuals.

Page 66 in the pdf is about changing brake fluid.

VAG technical data books did say 500ml per wheel that is true...but this is over generous as it is a fair bit more than the system holds. 2 litres will definitely do the job but so would 1.5l. I know that when I've completely drained my system off in the past it hasn't taken anywhere near 2litres to refill.


Martin

Appreciate the info here - top quality as usual. The German manual is v informative even though I cant read it - a picture tells a thousand words as they say! On page 56 it shows the caliper piston being fitted using a tool that looks like a vice - is this necessary? Reason I ask is I have removed the pistons and not yet tried to put them back in (waiting for new seals to arrive) - in Haynes it simply says 'push the piston back into its bore' - I was assuming I could do this by hand with a brute force. Will I need a tool to do it?

Last time I did anything with brake pistons, I used two G clamps - one across the face of the piston, and the other to do the actual pushing (if you know what I mean). Couldn't do it by hand.

California Dreamin wrote:The correct way to bleed (although most people don't bother) is to use something like a Turkey Baster

Or, if we're all feeling in the mood to invest in shiny tools, Mityvacs seem to be a LOT cheaper than last time I looked...

http://www.ebay.co.uk/itm/311133326090" onclick="window.open(this.href);return false;
or
http://www.ebay.co.uk/itm/191417934744" onclick="window.open(this.href);return false;

I've got one of the former on the way at the moment. I've used 'em before, and they really do make life a lot easier, but I've never been able to justify the prices before. However, I've currently got the Landy to fill and bleed after a complete brake rebuild, I need to replace a couple of brake pipes on the white van, and both the red van and the Pug are (over)due new fluid. Then there's the drum-brake 2cv van that I'll be starting to reassemble soon. At least the disk brake 2cvs use proper non-hygroscopic hydraulic fluid...

I think this is the point at which the 'cautionary note' is added in regard of damaging the master cylinder tandem seals. Unfortunately there have been a few incidents, particularly after manually bleeding, where the tandem seals have been damaged from riding over the ridge the seals would otherwise stop at. When bleeding the increase in pedal travel takes the seals over this 'wear point' and in some cases the seals can either turn back on themselves or damage can occur. Typically resulting in pedal creep under pressure.
I think these 'power bleeders' are the answer or if you are manually bleeding 'Fully open' bleed nipples to prevent internal pressure and use a slow/medium, pedal action to minimize the chances of seal damage.
Martin

I have one of the vacuum bleeders good in some ways but I can't use it on my Merc, it's something to do with the compensating valves in the circuits. Also, if you have arthritic hands it is a pain literally pumping the handle. The other drawback is that I found that air can be drawn in via the nipple threads which means that you cannot easily tell when all the air is out of the system. All in all I find that the Eezi bleed has less drawbacks for me.The only one being that you need to lower your air pressure in your tyre if you have tyres at 48 psi. (I burst a reservoir with too high a pressure!)