Permission to bleed the brakes...

[e34.535i.sport]

Hey guys been wanting to bleed the brakes for a while as they feel a bit less responsive than they used to (not bad or anything...) - so I tried to do a bit of reading up on it first.

I've bled brakes before on a ford escort without a problem with the Captain pumping the pedal etc...

From what I've read on here about the 535i it seems it requires a pressure bleeder? I have a normal piece of clear pipe and a small container on the end. I'm not looking to change all of the fluid, just to ensure there is no air in the system and to get rid of any crappy fluid left at the caliper end... Can I just use the normal method?!

I'm looking for the go-ahead here - anyone???!!!!

[Tiger]

It is best with pressure bleeder and it also saves you tremendous time. It is worth $50 investment so then you can change your fluid every 2 years.

You have to change all your fluid for the best pedal feeling.

[yaofeng]

Your leg muscle works. Or give your son a good leg exercise. You should flush the brake system every few yaers anyway. I am cheap.

[Rus]

Changed mine without a pressure bleeder. Works just like any other car I've changed fluid on. HTH

[E34-520iSE]

You can bleed them the same 2-man way you did your escort, no problem. Just don't forget to top the reservoir up from time to time.

HTH,

Shaun M

[Ross]

You may also gravity bleed. Just open the bleeder and let the fluid run until clear, topping off the resevoir as needed. Suck as much old fluid from the resevoir and refill before beginning. Begin at the farthest wheel from the master and proceed to the next furthest, etc. DON'T touch the brake pedal with an open bleeder or you will draw air in.
If nothing flows, the bleeder screw could be munged up. Take it all the way off and clean it out.
This is slow but effective and one man can do it without any special tools.

[johnbmw524td]

Not sure what you mean by "normal" method, but with the old 2-person bleeding procedure you risk pumping the master cylinder beyond its normal working range (i.e, pushing to the floor while you open the bleeder screw) and raking the piston seal over uncharted (and typically corroded) cylinder walls, resulting in more damage to the seal. Pressure bleeding keeps everything in place and avoids this unintentional failure of the master cylinder. Maybe try short strokes?

[yaofeng]

You need to state your concerns bleeding the brake using the leg muscle in more concrete terms. What are they? When you bleed the system the downstream port is open. The system will see far, far less pressure than during normal braking. The pressures are likely several orders of magnitude different. If any component is in a corroded state, bleeding by any method will not make it fail if braking on a sealed system has not.

[Ferret]

Pressure bleed would be best here I think, halfords or the like sell a cheap gunsons kit that you plug into your spare tyre for pressure.

Works really well as well as it tops up the reservoir as you bleed the system!

Whatever you do, dont let air get into the system as you bleed it up - you'll have to bleed up the ABS pump and it's not an easy job. I tried it once on a bosch abs pump in a peugeot - ended up taking it to a dealer in frustration!

[Ross]

What he is saying is the master will make a longer stroke with a bleeder open(pedal to the floor)than it ever does in actual service. Any corrosion in the far extreme of the cylinder will now abrade the seal. This is why short strokes were suggested.
The same thing often happens to brake calipers after pad replacement. With the piston way back in the bore to accomodate new pads the seal is riding on a portion of the bore previously not swept regularly by the seal and potentially corroded from fluid contamination. If corroded the seal either won't seal and leaks immediately or the rough surface wears the seal rapidly.
He makes a valid point.