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.

[Bill R.]

at least 2 cars a week for the last 35 years? Doesn't seem that
long.... but anyway, I've alway bled them the 2 man way with full stroke all the way down. I've never had a failure yet due to corrosion in the bore chewing up the seal. I've had some fail like a 65 mustang that sat out in the weather with the hood off and reservoir cap off for 3 years, but on that one everything was rusted, master cylinder , brake lines ,wheel cylinders etc.
Typically here in arizona moisture obviously isn't a problem so people rarely change their brake fluid on a regular schedule. I see fluid thats 10 years old and black. I flush the entire system and bleed with full strokes with no problems. If you have enough corrosion that you have to worry about the master cyl. seal or caliper seal hitting on damaged surfaces then you should have changed it anyway.

Bleed with full strokes and surge bleeding helps to remove more air than short strokes.

[Ross]

I've never seen it happen either but I've seen calipers go **** after new pads.
The principle is valid if perhaps overcautious.

[whiskychaser]

at least 2 cars a week for the last 35 years?
Bleed with full strokes and surge bleeding helps to remove more air than short strokes.

I must admit I havent done 2 cars a week but over the same time period I've used the same method with no problems. Ferret has warned about getting air into the ABS system. I have never experienced a problem but perhaps someone could shed some light on it for me?

[e34.535i.sport]

Hey guys many thanks for all the responses... Attempted to get going on it the other day only to find the bleed screw was tiny and the smallest spanner I had was 8mm. I'm assuming its a 6mm? I'll be getting one tomorrow and getting it done.

I'm worried about what Ross said about the capiler now... It's had new pads and not leaking or anything but the front wheels aren't spinning freely when off the ground... They'll move by hand but stop almost instantly after spinning them: Could this be related? I'm hoping bleeding will sort this anyway...

I was looking at my little container thing with the clear tube and it seems to have a valve on it that only lets stuff go one way... It reckons "1 man bleeding kit" but I'll still watch it and get the GF to push the pedal for me...

Thanks guys...

[Ferret]

I must admit I havent done 2 cars a week but over the same time period I've used the same method with no problems. Ferret has warned about getting air into the ABS system. I have never experienced a problem but perhaps someone could shed some light on it for me?

As far as I understand it there are voids within the ABS unit where the pump actuators are - there's a few cubic centimeters of fluid within the the unit. If you get air into these voids it's an absoloute bugger to get back out again.

The way the peugeot guys did it was to plug the car into something that caused it to trigger the ABS pump. While the pump was firing they undid each of the pipe unions at the pump and let the fluid spray out into a rag.

Really let a lot flow through as well - then bled it up normally and the pedal came back after that.

Dunno if firing the pump was strictly proper, but it was pretty impressive :D

Just keep an eye on the reservoir as you bleed the system!

[Ross]

I'm not inclined to accept Pugeot's practices.

[Washburn]

Pressure bleeders are mentioned a couple times. I have a vacuum pump one man bleeder that I've used on various cars. Does anyone see why a vacuum bleeder would be effectively any different than a pressure bleeder?

[Bill R.]

vacum bleeder both. I prefer the vacum bleeder if you follow the instructions exactly ,which means you have to remove the bleeder valves and wrap them with a number of layers of teflon tape so they will seal at the threads even when you have it open a half turn. That way the vacum can't suck around the threads and you just pull brake fluid only. Mine uses shop air . However if i have a helper i much prefer to do both a vacum bleed and a conventional 2 man bleed to make sure that i have all the air out. If you want a fairly cheap neat solution i also like Jeff N.s solution with the speed bleeders that you replace the bleed screws with. If you bleed your brakes often this is a easy solution.






Pressure bleeders are mentioned a couple times. I have a vacuum pump one man bleeder that I've used on various cars. Does anyone see why a vacuum bleeder would be effectively any different than a pressure bleeder?