I just changed my rotors and pads on my 1983 300SD, and also bled/flushed the brake fluid. It's the first time I did it, so I'm sure I did something wrong.

I'm noticing that the brakes don't respond until the pedal is almost to the floor. It was working before (pedal was responsive at maybe 1/4 way down) and I suspect something about changing/bleeding the fluid was not done right. There is no gradual 'pneumatic' feel as there was before (from the booster), now it just is a hard/firm braking when I press the pedal all the way down. Any ideas?

Is there perhaps a way with the vehicle stationary that I can check whether the calipers are functioning properly, such as if I have someone in the car and press on the brakes to see the calipers move?

I'm also noticing that JUST the driver's front brake/wheel seems to have some sort of strong vibrating/creaking noise as I am almost to a stop, and that the creaking persists for a few seconds AFTER I let go of the brakes and start moving again. It's almost like a sensation of the brakes slipping. I don't know if it's a loose caliper, if the caliper is stuck, there is air in the or what.

The only things that may be questionable about the job is if the caliper is slightly loose (the two main bolts aren't on tight enough) and possibly how I bled the fluid. I opened the bleeder, put new fluid in the master cylinder, turned the ignition to ON (so the booster would kick in), and then pressed the brake pedal maybe 20 times. I had it attached to a hose that went to a reservoir for my mityvac. I then pumped the mityvac for maybe another 10-20cc's until it was at maybe 90cc's. There was still little chunks of air (or bubbles) coming out/into the mityvac tube, so I'm not sure if that was a problem. The brake pedal pumping seemed to do a better job at getting more solid streams of fluid (thought there still were chunks of air) than the mityvac by itself.

I don't know if maybe there is air somehow getting back INTO the caliper, if this is preventing the brake fluid from doing it's job, the caliper getting stuck or what.

I checked the brake fluid level after about an hour of driving and stop-and-go, and it's still where it was when I drove off. So I don't think fluid is leaking.

The hard braking and the weird creaking/vibrating of the left front brake/wheel is something I don't think is normal and should not be left alone.

I also changed the motor mounts, which I don't think is related, since the sensations/noises I hear/feel is only when I brake.

Sounds like air in the system to me. As long as you are getting bubbles you have air in the system.

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1983 300SD
200000miles

I was worried that the air I saw was coming from elsewhere, ie the mityvac connection to the bleeder, since I kept pumping and probably got 100cc (a full cup) out of it (while the master cylinder was still at a reasonable level). I'm wondering how much fluid (cc's) is a reasonable amount, too much, etc to bleed through?

Is there a chance that as I bleed the brakes, that air will go back into the caliper? Should I keep on pumping until I get a constant stream of fluid and then tighten the bleeder without taking the line off yet? Maybe there is a better connector than the one I have, it seemed a bit big that it wasn't on tight enough, like it was letting air get back in.

I noticed that the (vacuum) gauge on the mityvac was never staying even. I have the small 100cc reservoir that takes a two-way cap, one tube to the bleeder, another to the hand pump. Air seems to be leaking through the cap, is there maybe a gasket for it I'm forgetting? It doesn't seem to be sucking very hard.

When I did my old 300D I couldn't get a good bleed on the system. Ended up having a shop use a pressure bleeder on it.

Were you using the full-sized vacuum tube onto the bleeder? I think if it doesn't fit snug, then it won't create any sort of vacuum/sucking.

There is a chance that air returns to the cylinder when you lift the pedal. The air runs around the threads of the bleeder screw. Usually, it's tolerable, but not always.

I recently bled the front calipers on the SDL (they were replaced). Instead of attempting the pedal pumping solution with the standing bottle of fluid, I simply opened the bleeder screw and sat back and had a cup of coffee. In about 10-15 minutes, clear fluid emerges from the opened bleeder screw.

You tighten the screw............and you're done. Couldn't be simpler............but, you just need to wait a few minutes.

I cannot be certain that such a procedure will work for vehicles that suffer air in the lines between the m/c and the calipers............that might require some pressure to force the air to the cylinders, but it absolutely works for caliper replacement only.

If you are certain that the m/c reservoir did not run out of fluid during your bleeding attempts, the above procedure should work fine for you.

I have been poking around and came across Build a Brake Bleeder, on how to create your own pressurized brake bleeder.

Apparently you attach a pressure gauge to the spray bottle, then a clear hose to a modified master cylinder cap that has a brass nipple/fitting screwed onto it (just drill a hole and then attach the nipple with some sealant). Once it's up to the right pressure (20psi only), you then open up one bleeder and let it come out into a container.

I figured since I already have the mityvac, I may as well put it in pressure mode, and attach it to the cylinder cap fitted with the nipple, rather than getting the whole spray bottle doohickey. Just pump until it's at the pressure and then open a bleeder. Stop. Refill cylinder (slowly depressurize), put mityvac-cap back on, pressurize, move on to next caliper. etc. Seems cheaper (that I already have the mityvac) than getting a whole unit built.

it may be cheaper, but it's NO WHERE NEAR as easy, or safe to use.
the pressure bleeder, fills the system as it bleeds. it's AMAZING how easy it is to use, and bleed an entire system.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

The last shop I worked in had a pressure bleeder. It was nice.

I've gotten good results using a mightyvac to do vacuum bleeding. I have hoses that fit the bleeder screws very well, and I always pump up a large vacuum before I open the screw, and keep pumping until I close it. This way any air that makes its way around the threads of the bleeder screw gets sucked out and not allowed back into the brake system.

The old two-man pump up, hold pedal down, open and close bleed screw, and repeat as needed way also works.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

..............provided that you do not use more than 1/2 the pedal travel.

I never like this procedure with old m/c............can result in the death of them.

A Motive power bleeder is one of the most worthwhile things I've bought for my garage. I know there are several imaginative money-saving ways to do it, but the power bleeder was worth the money to me just for ease and ending up with a properly bled system. Of course, it didn't fit on my dad's GM van, and I had no luck bleeding that the pedal-pump way (which I tried to do by myself using a 2X4) ... it really made me appreciate how nice it is to not have to do that for the Benzes!

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

... I'm just having a ball imagining this scenario... no chance there is a youtube video of it?

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I finally found my mityvac manual and kit box, and noticed there was a slightly smaller hose that fit MUCH better onto the bleeder. The manual also says that a flow of tiny bubbles is (probably) ok as long as they're not big, since this is air leaking through the bleeder threading.

The manual also properly showed how to hook up the pump to the bleeder. This is a MV8500 kit:
1) Take the two-way black lid, placing the 1 1/2" line between the 'TO PUMP' end and the pump itself.
2) Then attach the longer line (I think there are two lines, one is much thicker than the other - in which case you want the thinner one) to the other side of the lid
3) Use the black L-shaped fitting all the way at the bleeder end
4) Attach the last 1 1/2" line to the underneath of the black lid and then tighten the lid onto the cup.
5) Pump about 10-15 times, to around 25 Hg. The pressure should hold, for the most part.
6) Open the bleeder, and keep on pumping, until you get either a solid fluid or just tiny bubbles (around 60-80cc's). The tiny bubbles are from the bleeder threading and won't do considerable harm. Apparently you can put teflon/white plumbing tape around the threading to stop the bubbles, too.

I've already tried the front two calipers and will try the rear two in the morning, and will post a progress report.

I just tried the procedure above and any hand operated bleeder will NOT work from the bleeder end if there is air in the lines. I accidentally bled the master cylinder dry. =(

Any sort of suction on the bleeder won't work because the bleeder valve leaks air, unless you maybe get some teflon tape, etc... The problem is that there just is never enough suction to pull all the fluid through at once - air pockets stay stuck where the are while only small streams of fluid pass by to the bleeder.

After spending 4 hours and a full liter bottle of brake fluid, I've realized the only way to ensure that all air gets out is through a pressure bleeder that operates ONTO the master cylinder. I've concluded there's no other way. I've thought about an ad-hoc power bleeder using my mityvac (attaching to a modified master cylinder cap), but the hand pump mechanism is honestly not well suited (ie an inconvenient pain!) for high pressure pumping. I've probably spent $25 on parts for this ad-hoc system and I may as well pay a bit more for total peace of mind.

So I've ordered a Motive power bleeder for $60 including shipping. Seems like a small price for complete convenience and peace of mind.