General Brake Bleeding

[Mike Millar]

Hi Guys and Gals just a quick question regarding brake bleeding

Is it ok to use a vacuum pump to bleed the brakes

Cheers

M

 

[varesecrazy]

Hi Guys and Gals just a quick question regarding brake bleeding

Is it ok to use a vacuum pump to bleed the brakes

Cheers

M

Hi.

Normally fine.

Obviously you have to maintain the level in reservoir.

Is this a full flush.. or following work on one coner??

General advice.. do NOT risk pushing old fluid (and associated debris) back into ABS

Charlie

 

[Mike Millar]

Hi.

Normally fine.

Obviously you have to maintain the level in reservoir.

Is this a full flush.. or following work on one coner??

General advice.. do NOT risk pushing old fluid back into ABS

Charlie

Hey Charlie

Thanks for replying it's a full change
I work on air systems so hydraulic brakes aren't my strong point.

I have a vacuum bleeder like the one in the pic I'm assuming that will be fine

According to hayne's you start with the caliper nearest the Master Cylinder

I wouldn't have thought twice it's just the Haynes manual made a big deal about the ABS system

 

[varesecrazy]

I suppose there could be a concern with
Too strong a vacuum .. as its obviously a system designed for pressure.

Personally.. I would syringe out the reservoir.. (and refill with the start of the fresh fluid)
so minimising the amount of foreign matter floating around.. of course the breaking down of rubber lines may be the worst offender(but obviously basically adjacent to the bleed points)

If you are not in a vast hurry..

Worth enquiring in the TechTalk section.

Charlie

 

[Pugglt Auld Jock]

I suppose there could be a concern with
Too strong a vacuum .. as its obviously a system designed for pressure.

Personally.. I would syringe out the reservoir.. (and refill with the start of the fresh fluid)
so minimising the amount of foreign matter floating around.. of course the breaking down of rubber lines may be the worst offender(but obviously basically adjacent to the bleed points)

If you are not in a vast hurry..

Worth enquiring in the TechTalk section.

Charlie

I've had a Gunson Eezibleed for many years. It works by pushing fluid through from the master cylinder end and automatically tops up from it's own bottle. It uses air pressure from a tyre (spare if you've got one) but you must reduce the pressure - if you don't the result is spectacular and can involve a respray! I much prefer it to the vacuum type (my pal has one) because I find you sometimes get air bubbles which enter around the bleed nipple threads with the suction type so it's not so obvious when you've got all the air out of the brake lines.

I too like to draw off the old fluid from the master cylinder reservoir and refill with fresh before starting to bleed through. It's worth having a look in the bottom of the reservoir as there may be "foreigners" or "black gunge" which you don't want to flush into the system and you won't see that through the old dark coloured fluid. There is much said about back flushing dirt into the ABS module if you force fluid back into the system from the calipers (maybe when fitting new pads). After years of working on systems where a tandem master cylinder was a big deal I didn't pay much heed to this and have never had a problem when just forcing the pistons back and allowing the fluid to return to the reservoir. But it's always nagged away at my mind so, a couple of years ago I decided that if (and it's a big if) the bleed nipple can be easily slackened I would clamp off the flex hose and allow the old fluid to be expelled as the piston is pushed back. I thought it was going to be a big "phaf" but it's actually quite easy to do - admittedly it is a bit more fiddly on rear calipers where you are trying to wind them back at the same time. If I run into a seized nipple then I tend to just let the fluid go back. I've started asking around the chaps I know in workshops where I'm known and most say "let sleeping dogs lie". No one I've asked says ABS contamination is a problem they particularly recognize.