Help: questions about replacing brake fluid
 

I need to replace my brake fluid soon (like tonight). I've read all the DIY's I can find, but have the following questions.

1) Any suggestions on where to find a tube to put on the bleeder nipple ?

2) Will it be obvious when the old fluid is done, and the new fluid starts coming out? I'm ended up buying Motul 600 from Dave Zeckhausen.

3) I'll be using the "helper pumps the brakes" method. Any guess how many pumps are needed? Obviously it depends, but are we talking 10, or 100?


WARNING: If I run into trouble, I may be looking for people on IM to bother. :eeps:

1) Home Depot or Lowes
2) It should be pretty obvious, the Motul 600 is red right?
3) hmm... not sure, I have a pressure bleeder

Thanks ayn.

> 1) Home Depot or Lowes

Cool. I guess they sell generic clear tubing? What diameter are we talking about? I guess I could go home first, look at the brakes, then go find something to fit.

> 2) It should be pretty obvious, the Motul 600 is red right?

Maybe. :dunno: Didn't open the bottle yet.

It'll be obvious.

The fluid in there looks like urine, after a night of hard drug use and binge drinking. The motul will be only slightly yellow.

Thanks Nick.

I'll use hard drugs and binge drink tonight, and compare to the old fluid as well.

Awesome. Just remember that you need to moderate it enough that you'll be able to tell the difference tomrorow evening.

1/4 inch sound about right?

1/4" ID (inside diamater) should be about right.

You do realize that Motul 600 is EXTREMELY hydroscopic, and needs to be changed more often than other fluids?

Fine if you are into tracking and plan to flush several times per year, not so great for a street car.

For a primarily street car (for those who care) I recommend Castrol GT LMA fluid. Works well and one of the least hydroscopic fluids.

Cool. One more dumb question.

I'm putting on new pads as well. Would you swap the pads before, or after, the bleeding?

Yeah, I went round and round, and Dave Z. convinced me to go with Motul and eliminate boiled fluid as a source of concern. The E30 brakes are tiny, and I have no idea how well I'll manage them (my first track session).

It could be major overkill, but I don't know enough to decide how much is "enough". If I have to replace it again soon after, so be it.

You can always put the Castrol in for the winter season.

Swap pads first. Suck the old fluid out of the reservior, put in the pads, then suck out the stuff that's backed up from pushing the pistons in and bleed.

Thank you, thank you, thank you...

Going out to play with the pads.

here ya go

vinyl tubing, 1/4" id, 3/8" od
tubing splice
cheapo water bottle

http://surface-energy.com/carmudgeons/bleederparts.jpg
http://surface-energy.com/carmudgeons/used.jpg

What does your bong have to do with anything? :lol:

Hey Elbert! Thanks, that's pretty cool. I did pick up some 1/4" inside diameter at home depot and it fits fine. Changing brake pads is ridiculously easy. But I got stuck on the rear because I don't have an allen wrench large enough. :rolleyes:

A few more questions, for those willing to put up with me:

1) The bentley says that the "mounting bolts" are self locking and must be discarded. WTF? Do people buy a new bolt every time they swap pads?

2) Do I need anti-squeel on the back of the track pads? Is that functional, or just for getting streed pads ultra-quiet

3) My hub/rotor's aren't the cleanest (pic 1). What would you attack that with?

4) I've got some red gunk (see pic 2.) It looks like rust in the blurry pictures, but in person it looked more like some kind of buildup. Should I be removing this with some kind of brake cleaner?

5) My "guide pin protective boot" is old and torn. (see pic 3) I'm thinking of replacing this after the track event, unless someone convinces me that's a bad idea.

Thanks

:eeps:

I hear brake fluid works great in bongs. It cools the smoke nicely, give it a nice flavor. Just be careful not to take too many hits in succession - you might boil the fluid. :devcool:

Hey Rumatt, you might want to get some hex sockets, allen keys suck.

1. Are the "mounting bolts" the bolts that hold the rotors in place? I replace them if they look rusted. They probably should be replaced regardless, but I will re-use them. Put a tiny dab of anti-seize.

2. I don't use anti-squeal, track or street.

3. wire brush

4. wire brush

5. You might want to replace it now, it can't hurt. You might want to get those solid bushings instead while you're at it.

of course, ymmv... after all, I apparently have a bong that may be in use :shock:

No, just the bolt that goes into the guide pin, to hold the caliper in position. According to the bentley, you need new ones every time you change the front pads.

Thanks for the other answers.

BTW, there's a chance I'll be in Columbus in June. If so, you, Andy and I should have a :drink2:.

Really? That's the first I've heard that they need replacing. Uh, needless to say, I don't replace them.
Sure, just lemme know when you're in town

EDIT: wait, what car is this for?

E30

I've used one of these for years and years......

http://www.rdent.com/images/eezibleed.jpg

It has many nice aspects - Some of them are-

• One Person bleeding
  The same cap works on both my BMW's and Mercedes.
  I use the spare tire as the pressure source. Forces me to check (refill) the tire pressure when I'm finished
  I don't have to get my wife to help. :)
  I can be finished doing all 4 wheels in 20 minutes (2002) and 30 minutes (420SEL)

Cost me ~$35 and worth every penny IMHO.

Get a hex socket, I have a very nice Snap On one that is a solid piece, unlike the Craftman which look like a chunk of allen key shoved into a socket. They should be 7 mm front and rear for the caliper guide bolts.

1) I never have, unless you over torque them, ala DIY on BF.

2) Street only. Smells bad when you seriously overcook the track pads. :)

3) Wire brush, by hand or rotary in drill or other power tool.

4) Same. Maybe hit it first with brake cleaner to see if that works.

5) You should replace it now, as that boot is part of the sleeve that guides the guide pin. I agree that the soild bushing setup from BimmerWorld (you can also buy it from Turner and others, but BW makes them) is nice, but it does require additional maintenance. NOt a big deal if you are swapping pads fairly often. Not good for those who don't swap pads a few times per year.

NONONONONO!

Back out the bleed valve screw when you push the piston in. This is especially important if you have ABS! You do NOT want the rust / water / crud from the caliper going back into the brake system.

John V

Thanks John. I didn't need to push them in at all because the old pads weren't worn much. But FWIW, the Bentley just says to push them in. :dunno:


I managed to make the rookie mistake of letting the tank run dry and air got in, so I had to start all over. What a dumbass :rolleyes: :rolleyes: (after a panic'd instant message to Clyde and Nick. Thanks for the advice. :thumbup: ) I was confused because the container didn't look empty, but the pedal went straight to the floor, and wouldn't gain pressure. But after enough pumping, it came back, and I eventually worked the bubbles out the back.

I also changed the fuel filter and fuel pump. That wasn't bad at all, but I was disappointed to see that the fuel pump wasn't original (the tab on the wiring clip was broken off, suggesting it has been changed). Shouldn't they last at least 10 years? I'm wondering if there's too much pressure or something, causing the pump to overwork and keep failing.

Fuel pumps on E30s are a notoriously weak point. Someone might have changed it even asymptomatically as insurance.

I don't always change fluid and pads at the same time, and always just push the piston back. Since it's a closed system (if it isn't, something's wrong!), there's no extra crud there to be pushed back - and everything is flushed clean in the other direction at least yearly when you bleed the fluid.

"closed system." :lol: :lol:

That would be true if an airtight seal existed at the master cylinder cap and if you never opened the top. The fact is that with brake fluid having such an affinity for water and water being prevalent in the air we breathe, water gets into the brake system.

Calipers are made of ferrous metal, and as such they will rust when there is water present. I'm guessing you've never rebuilt a brake caliper after buying a used car whose previous owner didn't flush the fluid. Rust, rust rust. Even if you do flush yearly, rust will still form and it's most likely to dislodge when you're pushing a piston back into a bore.

Bentley manuals are terrible. They miss all manner of critical steps, at least the E36 version does. :rolleyes: Oh, how I miss my 1,000 page RX-7 factory shop manual...

Pushing a piston back without opening the bleed screw is fine if you like gambling. I tend to keep my cars for a long time. :dunno:

In my cars, my friends' cars, local track cars, race cars... I've never heard of a problem with that. :dunno:

THAT'S where the problem resides.

...yet. :P
Not entirely. Brake components still rust, even if the fluid is flushed regularly. It's unavoidable. Unless of course you can hermetically seal your brake fluid container, your master cylinder, AND the transport device between the two.

Oh, did I mention releasing the bleed screw makes it much easier to retract the piston? :) There's no reason NOT to do it.

1) Hardware store.
2) Yes
3) 10 to 12, go till you see new fluid.
4) Yes, replace you pads first

What car? Do you have ABS? If so after bleeding go out and romp on the brakes to activate the ABS a couple times then re-bleed. This gets the old fluid out of the ABS actuator

Fuel pumps in BMWs can be problematic, if hte person runs the tank low. They are mounted in the fuel tank, and cooled with fuel. So running low reduces cooling of the pump motor.

While I agree with JohnV intellectually on the pushing the piston back in, I just shove them back in most times. :)

Interesting. It's an E30 with ABS.

The ABS question has been debated, and again - although it's technically "better" to actuate the ABS, it's very common in local club BMWs to just bleed them normally. Again I know a lot of BMWs from E30s to M coupes that have logged a lot of track miles with normal bleeding on ABS setups.

If you get into ABS between flushes, you are flushing the ABS system.

Or if you are truely an*l, flush, go out and activate the ABS 5 - 6 times, then flush again.