need help bleeding brakes...ASAP - Page 2 - PeachParts Mercedes-Benz Forum

cmbdiesel · #16 04-10-2009, 12:57 PM

Quote:

Originally Posted by BodhiBenz1987

Yes, engine off. Does it build any pressure if you pump it a few times quickly (with bleeder closed)?

I ended up investing in a power bleeder for this job ... took a lot of the puzzle out of it. Without one I think the big key is not letting up the pedal while you have the bleeder open. Pump, pump pump pump pump, hold down pedal, open bleeder, let fluid out, close bleeder ... pump pump pump, etc.

I use the invaluable MityVac.

Brian Carlton · #17 04-10-2009, 01:00 PM

Quote:

Originally Posted by mouramen

But there is no pressure on the pedal now, it sinks easly...
I'm doing the procedure with the engine turned off, is this right?

The reservoir is divided into two sections..........one for the front.........one for the rear.

Your likely issue is that you've got no fluid in the reservoir for the rear brakes. The design of the reservoir is not all that great...........the front section needs to be filled to the very top to allow fluid to spill over to the rear reservoir.

Check the rear reservoir by looking at it from the passenger side...........it's probably empty.

leathermang · #18 04-10-2009, 01:02 PM

Quote:

Originally Posted by compu_85

If you can get a longer line and put it in a container with some brake fluid (an old brake fluid bottle works good) you can just press the pedal over and over without closing the bleeder: it will just suck back on the fluid in the container. For the final bleed close the valve, have your helper press the pedal hard, then open and close the bleeder really quick to give a quick burst of fluid.-Jason

I suggest that is not a good plan.
We are dealing with fluids... seeking their own level, taking the easy way first, ... all the usual fluid physics....
That seal around the nipple at the top is not sealed when the nipple is open for the fluid to be coming out...
When the pedal is allowed to come up it will try to suck... but fluid has more resistance than air... and it will suck air back into the system rather than the new fluid..

mouramen · #19 04-10-2009, 01:35 PM

Quote:

Originally Posted by Brian Carlton

The reservoir is divided into two sections..........one for the front.........one for the rear.

Your likely issue is that you've got no fluid in the reservoir for the rear brakes. The design of the reservoir is not all that great...........the front section needs to be filled to the very top to allow fluid to spill over to the rear reservoir.

Check the rear reservoir by looking at it from the passenger side...........it's probably empty.

Humm...
Didn't knew that... I'll check the reservoir, but I think mine isn't divided...

Been PRESS - OPEN NIPPLE - CLOSE NIPPLE - DEPRESS for about 20 minutes and nothing!!!!! Only bursts of air...

mouramen · #20 04-10-2009, 01:36 PM

Same thing now in the other rear wheel... Only air...

mouramen · #21 04-10-2009, 01:38 PM

If the back fluid reservoir was empty it shouldn't send air thru the lines right?

cmbdiesel · #22 04-10-2009, 01:39 PM

Quote:

Originally Posted by mouramen

Same thing now in the other rear wheel... Only air...

What Brian said.

Sounds like you've completely emptied the reservoir.

cmbdiesel · #23 04-10-2009, 01:41 PM

Quote:

Originally Posted by mouramen

If the back fluid reservoir was empty it shouldn't send air thru the lines right?

The reservoir is where the new fluid comes from, if it is empty it is where the air comes from.

mouramen · #24 04-10-2009, 01:43 PM

Quote:

Originally Posted by cmbdiesel

What Brian said.

Sounds like you've completely emptied the reservoir.

Nope, it's more than half fill...
I'll check the reservoir division thing now!

I'm doing this with the reservoir cap off, is this right?

JonL · #25 04-10-2009, 01:54 PM

I tell my helper "pump," let him pump four or five times, then I say "DOWN." He holds it down while I open the bleeder, and then close the bleeder. Then I say "PUMP" again. After three or four cycles, I add the word "HOLD" after "DOWN" so I can go check the reservoir before he comes up on the pedal and possibly sucks air.

I also firmly (no pun intended) believe that the pumping should be relatively slow and deliberate, with firm pressure on the down stroke. I like to do it slowly because I believe that rapid motion will encourage the air to mix into the fluid and create tiny bubbles that migrate through the line, whereas a slow motion on the pedal will encourage the air to remain segregated and concentrated for more effective removal.

Finally, don't forget that brake fluid will remove paint. Be careful topping up the reservoir, be careful where the bleed fluid goes. I usually put the cap on loosely during the process because sometimes fluid can splash out of the reservoir during pumping.

And start at the right rear, then left rear, then right front, then left front.

mouramen · #26 04-10-2009, 02:00 PM

I just topped de reservoir to the TOP!! It took quite a bit of fluid to top it, it looked liken the fluid was going somewere...maybe the rear...LOL

I'll try now!

leathermang · #27 04-10-2009, 02:18 PM

Quote:

Originally Posted by JonL

believe that the pumping should be relatively slow and deliberate, with firm pressure on the down stroke.

I think so also... a few gentle pushes until some resistance is felt... and hold the pressure works just fine... not trying to blow out any seals anywhere... or get leg exercise... just push unwanted air out of the system with the fluid which is associated with it...

mouramen · #28 04-10-2009, 04:58 PM

Quote:

Originally Posted by Brian Carlton

The reservoir is divided into two sections..........one for the front.........one for the rear.

Your likely issue is that you've got no fluid in the reservoir for the rear brakes. The design of the reservoir is not all that great...........the front section needs to be filled to the very top to allow fluid to spill over to the rear reservoir.

Check the rear reservoir by looking at it from the passenger side...........it's probably empty.

Yep, only when I topped the reservoir I was able to bleed the back lines, inspite the reservoir seamed full, the rear one was empty...

Note to self: Always bleed the brakes with the reservoir fully TOPPED!!!

Thanks for all your inputs guys!!!

I was so happy that I changed the PS fluid too!

Tomorrow will change the Diff fluid and the engine oil!!

tbomachines · #29 04-10-2009, 07:41 PM

Glad to hear you were able to get to the bottom of things! I'd suggest picking up a mityvac/brake bleeder, its a huge help!! Not to mention you'll be able to diagnose any vacuum issues in the future.

Skid Row Joe · #30 04-11-2009, 01:11 AM

Invest in a one-man hand trigger pump to bleed the system, and 86 the guy pumping the brake pedal. Works like a charm for me.