Brake bleed - PeachParts Mercedes-Benz Forum

96C280 · #1 02-09-2003, 04:38 AM

Ok guys, here's the dumb questions.....

Where are the brake bleed screws and do you have to take the tires off to access them? What does it look like? And what tools do you need to loosen them? Obviously, I'm thinking of bleeding the brake fluid. Thanks.

J.HIDALGO · #2 02-09-2003, 07:46 AM

You don't have to take the tires off, if you have a lift. Otherwise, it would be a lot easier to take the tires off. Plus you can check all the related components while the tire is off.
The brake bleed screws are on the top inside (away from the tire) of the calipers. It is probably covered with a rubber cap. Just remove the cap and it should expose the nipple like screw. You will need a 10 or 12 mm flared wrench (a regular will work too). Start with the fartest from the brake reservoir (right rear tire) to the closest (left front tire). I use the "brake bleeder", it works great...
Good luck!

Mike Richards · #3 02-09-2003, 01:28 PM

Some use a 9mm to loosen brake bleed screws. In my case, I find that the flared wrench doesn't access and connect that well - a deep socket 9mm works best to loosen and tighten.

Gilly · #4 02-09-2003, 04:40 PM

I just use a 9mm box end wrench. I put the wrench on, then you can put a 1 or 2 foot section of clear windshield washer hose on the end of the bleeder screw, and put the end of the hose into an old glass jar, like an old canning jar.

Gilly

J.HIDALGO · #5 02-09-2003, 05:12 PM

daddiojiggy · #6 02-09-2003, 08:37 PM

i do it the same way with one difference.i have the end of the tube immersed in brake fluid in the jar.i'm sure you do it this way as well but forgot to mention it

Gilly · #7 02-09-2003, 09:05 PM

No, I start with the jar empty. Why have the end of the tube in brake fluid? I use a pressure bleeder, if that makes any difference to you. I'm talking about doing a brake fluid flush here, but I do the same if I am doing a air bleeding job.

Gilly

rickjordan · #8 02-10-2003, 12:59 AM

Just exactly how do these power bleeders work. I have seen some that are connected to an air compressor, but others are manual. Do you open a bleeder screw and push all the fluid out, then bleed the brakes with new fluid?

Jim's500E · #9 02-10-2003, 12:07 PM

Motive products makes a nice $45 brake bleeder...works on pressurized air..simple stuff. Do a search on the name.

German Parts and Resto is where I got mine...many others carry them too.

Thomaspin · #10 02-10-2003, 12:55 PM

It has a built in rubber seal and drain hose attached, and has an integrated handle for torquing - you can see it on the brake job illustrated on my web site. (Not one of my greatest photos, I'm afraid).

I don't see it on their German or US sites, but it may be in the hard cover catalog.

Using a pressure bleeder (I use the Eezibleed) once the car is on jacks with wheels removed, I can flush and bleed all four brakes in 3 minutes - just timed it two days ago - without rushing.

I have read many times that pumping the brake pedal runs the risk that you run the brake fluid in the reservoir too low and heretofore unused (and potentially corroded) parts of the brake caliper pistons are forced into their respective counterbores in the caliper, scoring the surface and destroying the brake. I wonder if anyone can confirm this?

Gillybenztech - am I right in saying that pedal pumping is ineffective with ABS brakes? And even more so for ASR?

Gilly · #11 02-10-2003, 10:16 PM

Thomaspin:

Quote:

Gillybenztech - am I right in saying that pedal pumping is ineffective with ABS brakes? And even more so for ASR?

Do you mean while driving, like trying to stop the vehicle? Or brake bleeding/brake fluid flush?

Quote:

I have read many times that pumping the brake pedal runs the risk that you run the brake fluid in the reservoir too low and heretofore unused (and potentially corroded) parts of the brake caliper pistons are forced into their respective counterbores in the caliper, scoring the surface and destroying the brake. I wonder if anyone can confirm this?

No, I can't confirm this. I can't even envision what you're trying to say.

Quote:

It has a built in rubber seal and drain hose attached, and has an integrated handle for torquing

It's made out of a piece of steel tube, not tool steel, and quickly wears out. The 9mm hex wears out. It frequently requires repair where the plastic/rubber hose is supposed to attach to the bleeder screw, or it'll leak brake fluid. It may be OK for a DIY'er, which is fine. I haven't seen ours for quite awhile. I thnk someone probably pitched it. (no, not me, I just ignored it).

Gilly

jsmith · #12 02-11-2003, 08:02 AM

Quote:

Originally posted by Thomaspin
I have read many times that pumping the brake pedal runs the risk that you run the brake fluid in the reservoir too low and heretofore unused (and potentially corroded) parts of the brake caliper pistons are forced into their respective counterbores in the caliper, scoring the surface and destroying the brake. I wonder if anyone can confirm this?

i believe the risk has to do with the master cylinder and not the caliper and it is when an inexperienced person makes the mistake of pumping the brake pedal to the floor...

Thomaspin · #13 02-11-2003, 10:24 AM

Q: Do you mean while driving, like trying to stop the vehicle? Or brake bleeding/brake fluid flush?

A: I mean when brake bleeding/brake fluid flush.

Q: No, I can't confirm this. I can't even envision what you're trying to say.

A: I think 'jsmith' has answered that one, thanks.

Q: It's made out of a piece of steel tube, not tool steel, and quickly wears out.

A: Yes, I use mine twice a year at most and, accordingly, it is used infrequently, so it's just fine for this DIY'er! Incidentally, Stahlwille provides a lifetime warranty on most of its tools purchased in the USA.

Thomaspin · #14 02-12-2003, 10:59 AM

....for that sweet brake bleeding tool - it is # 3006 (74 66 00 09) but sadly appears to have been discontinued.

This will doubtless make Gillybenztech a happy camper, but I still commend the tool to those who do not fix cars for a living. It works well - if you can get it.

Take a look at http://www.stahlwille.com/closeout.htm - some nice, expensive torque wrenches ($600-800 new) being remaindered for <$150.

Gilly · #15 02-13-2003, 09:39 AM

Thomas:
When bleeding the brakes, you never want to pump the brakes when a bleeder screw is opened, as the release of the brake pedal will allow air to go into the screw, and then of course into the caliper. The pedal has to be pumped up when the screws are all closed (this is when you worry about running out of fluid in the reservoir), then once there is a pedal "feel" (pedal is somewhat higher, usually 3 to 5 slow strokes of the pedal is enough), then the pedal is held down slightly, while the bleeder screw is loosened. The "pumper person" should hold the pedal down until the person running the bleeder screw says "pump it up" or whatever verbiage is agreed upon. DON'T say "pump it up" unless you have closed the bleeder screw.

Gilly