OK, I give up. After doing a brake 'freshening' on a functioning 230SL, I am giving up on figuring out why it will not funtion now. I rebuilt the master, calipers, wheel cylinders. I replaced all four flex lines. Attempts to bleed down the system have failed. I bought a new master today. Bleed down goes normally (bubbles first, then good steam of fluid. After bleeding all four corners in the accepted patten, I have NO PEDAL. There is no movement of wheel cylinders or caliper pistons. There are no external leaks. I have moved the excentric fulcrum pin through all angles of rotation. Any 'tips' at this point would be greatlly appreciated unless someone is lurking in the wings awaiting me to set it at the curb (could happen).
Much Thanks
BB

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BBAY

Hmmm.

You must have air in there somewhere, or a busted line you've not found.

Did you get any pedal while bleeding the calipers, or did it stay soft then?

Make sure you don't run the master cylinder too low on fluid while bleeding -- you might not notice a "gulp" of air going in, and that means no pedal.

Have you pumped up the pads yet? If you put new pads in, you have to pump the pedal several times to move them out to touch the rotors. I didn't do this once, and we have a rather steep slope on the drive from the garage to the road. I backed the car out (my old Buick) and the pedal hit the floor! I remembered I hadn't pumped them up first, so was madly thumping away, hoping I'd get some brake before I rolled out onto the road.

My brother wanted to know what the funny thumping noise was, and nearly split his sides laughing at me when I told him.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter:
Thanks for the reply. I consider myself a pretty accomplished mechanic after home wrenching for 40 years. I do mainly British, but have a '63 300SL and an '85 500SL in the Mercedes side of the shed. I immediately concur with your evaluation, but have been on the problem for a week. There is no fluid loss. Due to the dual nature of the hydraulic system,if there were an open line, I would expect a failure in either the front or rear system. I get no movement in either the front or rear pad/shoes. There are no fluid losses in the reservoir. There are no puddles. I am in pain.
Regards
BB

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BBAY

Now this does sound like fun!

Have you checked to see that you can generate pressure at the master cylinder? I don't know how you could get air trapped in there and still get fluid out the caliper bleeds, but it sure sounds like that is the case.

Also, I've know systems to hold huge amounts of air -- took an amazing amout of fluid to get the brakes on my brother's chevy 1-ton to work, the right front must have a mile of line or something.

You might want to pull the master and do another bench bleed -- you can check for it's ability pressurize the lines at the same time. Its always possible you got an ancient master cylinder in which the rubber was already gone.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Sure sounds like there must be air left in the master cylinder ,I have had luck bench bleeding MB masters by finding thick walled vacuum tubing or rubber fuel line that is slightly bigger that the brake line outlets on the master cylinder and screwing the tubing in all three outlets and putting the other end of the tubing in the fill hole in the master culinder resivor which of course is full of fluid ,sometimes takes 50 or more pumps to get all the air out............

William Rogers.......

Thanks for the replys. After pumping several quarts through a factory fresh master, the thought that I have not been energetic enough doing the bleed is a hard thought to swallow. The run to the front calipers is so short, the possibility that there is such a great quantity of air in the system that I get insufficient pressure to even budge the pistons seems to defy the laws of physics. I welcome all suggestions, including additonal advice to bleed the air out.
Regards
BB

__________________
BBAY

Are you using a power bleeder or the "pump the pedal" method?

I have had problems in the past getting rebuilt brake systems bled, I switched to a power bleed setup and have not had a problem since. It takes about 1/10 the time and works perfectly.

One some models the amount of fluid held in the master cylinder for the rear brake circut is very small, in the W124 two or three pumps will exhaust the fluid supply. Make sure that the rear brake circut has an ample fluid supply.

What's the angle on the master cylinder on the W113? Fairly flat or canted upwards a bit?

I don't believe you should have air in there either, but something is wrong. Again, I'd check to make sure that you can generate pressure at the master cylinder itself before going further, you will just be chasing your tail.

Fixed the problem on my brother's truck -- he's loosened the lines on the master cylinder to change it before we found the bad wheel cylinders in the back, and forgot to tighten them. Works much better now, no fluid leaks, either.

You should be able to gravity bleed the fronts, at least, so something screwy is going on here.

You must have master cylinder piston travel, or you wouldn't get fluid pushed out of the calipers, and if they were all stuck (very unlikely) you would have a nice hard pedal!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter. Thanks for the reply. Though I prefer not to power bleed due to the danger of spraying the paint remover DOT3 all over the place, I did set up my bleeder today. I pushed about 2 quarts through the system. Then the poor seal against the lip of the flexible reservoir sprayed the paint remover DOT3 all over the place and destroyed the new paint job in the engine bay. By the way, after the power bleed, I had zero pedal front and rear. The car is level. I notice that on the return stroke of the pedal, there is a fountain of fluid erupting from the rear chamber of the reservoir. As the reason for the brake system needed bleeding was that over the last several months I stripped the engine bay to perform a show quality repaint and detailing of the area, the fact that this effort was for naught due to the paint damage, I am more than discouraged.
Regards
BB

__________________
BBAY

BBay:

Something is wrong with the master cylinder. Some fluid movement is normal, but it is usually just upward flow as the pistons move forward until the fill orifice is covered. I don't remember fluid coming out on the upstroke. I would see if you can generate pressure at the fittings on the cylinder. If not, remove and disassemble, sounds like something isn't right way round in there.

Paint will be fine if you imediatly was down with copious quantites of soapy water to remove the glycol before it softens the paint.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks to all who took the time to respond to my request for advice. While I would prefer to just slink away in embarrassment, I will expose my senility to the world and tell the truth as to the cause of the problems (those under 50 may snicker). I inadvertently installed the front calipers right for left. This left the bleed nipple on the bottom vs. the top of the caliper. Though this fact should have only impacted the front system, the rears also were affected. This might be due to a restricted pedal movement or ineffective self adjusters. So...I have brakes and a red face. I also have an engine bay repaint to do and a new unneeded master cylinder. I think I'll buy a bottle of Ginkgo Biloba and/or Jack Daniels. Thanks again, all, for your patience and assistance. BB

__________________
BBAY

Um, uh, that would do it, I suppose!

I only take calipers off one at a time because I'm rather dyslexic. Right from left is impossible some days, and up from down is problematic when lying on my back.

Pedal has to go WAY down to work the rears if there is no pressure in the fronts.

You have drums on the back? Thought the W113 was discs all round.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

The 230SL has rear drums. Glad all is well - sorry the power bleeder advice did not work out too well for you engine compartment.