Update - done and done. Perfect working brakes now.

Had to break down and purchase a rear caliper for my 1988 300SEL today. Removed the hose and the caliper was still sticking, so we assumed the caliper was bad. Within 2000 miles it had already eaten up the new brake pads we had installed! We already had the new hose, so went ahead and installed it as well.

This evening me and my dad tried bleeding the brakes, starting at that wheel (right rear), but the pedal will not pump up at all. Also when the screw is turned, nothing will come out but air. No fluid at all. We tried it about 30 times. Reservior is staying full too. No fluid coming out. I dont think the master cylinder is bad, because the brakes were working fine before, other than that RR sticking some. We had just decided to replace that hose, as someone said the hose may have swelled up, but even when removed, it was still sticking.

Anyone know what is going on? Is there a special way to bleed brakes on a W126? We have never done brakes on a W126 (other than new pads before), so we are clueless as to what is going on.

Thanks for any information!

I did a search and confused now. Read something about needing a bleeder? Also, there appears to be no fluid in the back of the reservior. I read that is for the back brakes?? How do you get fluid in there?

Apparently Mercedes brakes are not like your typical American or Japanese car.

Yes, a power bleeder is the easiest and quickest way to bleed the brake fluid.

You simply have to pour additional fluid into the reservoir in order to fill the rear half.

Thanks. That may be why we were only getting air then, because the rear was empty.

... but is it possible bleed w/o a bleeder? Out of all of the brakes we have done before, we have never needed a bleeder when replacing the calipers. I dont have one.

Yes you can bleed these without a power bleeder. Just like any other vehicle... pump and pump via the pedal.

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'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

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Even though it's full, slowly pour more fluid in!

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That can do damage to an older master cylinder though.....I always try to avoid doing it that way. I bought a power bleeder years ago, it is very helpful.

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Johnathan is correct. Although there is only one fill opening, the reservoir is divided into three compartments---one for the front brakes, one for the rear brakes and one for the clutch circuit (not used on your car). The compartment for the rear brakes only gets filled after the front circuit is completely filled. Once properly filled the brakes can be bled the old fashioned way without problem. I would top up the brake fluid after no more than 10 pump and bleed actions to prevent reintroducing air into the rear circuit due to low fluid in the rear reservoir. Mark

I just replaced rear calipers and flushed new fluid in.I had a helper,the book says to start with wheel furtest from master cylinder( passenger rear,then driver rear,passenger front,then drivers front). Ok with my son manning the brakes,I have him pump 10 times,hold it to the floor open bleeder Repeat,till fuild bubble free comes out.Takes maybe 5 times till new fluid shoots out(empty master,with turkey baster,pour new).
I repeat this on all 3 remaining wheels.Some times little bubbles will still remain,what I do is take a stick or something to hold down brake pedal at night.Maybe take all week.Soon you will have top working brakes.
Note* Always check if brake pads slide freely,I have had to grind coatings that stick in calipers, or the caliper itself.

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For less than the cost of 30 minutes labor at most shops you can buy a pressure bleeder that makes a one-man 20 minute job of bleeding brakes. Should cost around $50. or less with the correct adapter for your car and it won't take "days" to do the job. The one I use is a Motive Products Model 0100. Comes with old Benz adapter and is available many places including ebay.

Some advocate the use of a vacuum bleeder such as MityVac but the vacuum bleeder is vulnerable to sucking air in around the bleed screw threads when it is loosened.

very few people pay head to above , When the pedal is pumped to the lower end it pushes the cylinder seals into unused and rougher areas. Shortly after they fail due to the abrasion. If necessary to bleed without a bleeder than place a block of wood under the pedal to stop it from bottoming out .
mak

Thanks for the replies guys. Yeah, I told my dad about this and he filled the back reservior. I told him what I leaned here... just to slowly keep pouring. It was no wonder was getting nothing but air.

I have to go to Knoxville tomorrow, but we will bleed when I get back home. I thought this caliper had stopped sticking but apparently not... it has been dragging all of this time. The pad was worn WAY down, but the driver side was still like new. I suspect I (well, my mom now, lol) will surely feel more power and better MPG.

Thanks again!

Oldsinner111.... you are just down the road I see! I am in Bristol - what, 20 miles away? Small world!