Follow the correct bleeding order.

Passenger rear, driver rear, passenger front, driver front.

__________________
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The 'Noid is always a great convo starter.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
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OKAY. WTF!!!!

I took off the res (after sucking it mostly dry.
I bled the MC while on the car, the DH pumped slow while I fed fluid into the MC and saw the fluid come out the screw lines, screwed the lines back in while full. Put the res back on, filled totally full, watched the bubbles and filled until no more bubbles in the res, bled rear pass side, bled rear drive side. Had my big son keeping the res filled to the top during the whole bleed process so that never went low. The entire res was full the whole time.
STILL NOTHING COMING FROM THE FRONT BLEED LINES AT THE WHEELS!!

Please help me out!!! This is the last nice day for a few weeks and I need this car running!
Thanks!

__________________
Ginny in Denver-ish
78 300SD, 265K (mine)

You need to find out how far the brake fluid is getting - loosen the flexible pipe at the joint between hard and flexible lines (high point) - see if some comes out there (9mm open ended spanner if I remember correctly).

If it comes out of that then loosen the flexible pipe at the caliper with out tightening the top one - because the flexible pipe is not flexible enough to do up one end or the other: it just springs back.

If fluid leaks out of both ends of the flexible pipe then you know that is still good.

If that is the case move to the caliper bleed nipple. Take it out - all the way - clean it.

(I must say if you'd drained the system this way - instead of sucking fluid out of the system - you would have found this problem earlier)

You should then be able to push fluid through. If not a caliper piston could be stuck. Then you have another problem.

Good luck.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Ginny,

Most likely, the rubber hose feeding the front caliper has swollen shut. Therefore, no fluid is flowing through.

I bet that even if you removed the bleed screw there would still be no flow.

Replace that front brake line and you should be all set.

Ben

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Ben
1987 190d 2.5Turbo

A stuck piston shouldn't have any impact on the bleeding process.

Depends where it is stuck - and on the caliper design (which I'm unsure about) - but usually the supply hole going into the piston sleeve of a caliper is on the end wall (so to speak) and the bleed vent is often on a side wall. A piston could in principle be stuck with muck at the end wall and thus the bleed vent is blocked. There would have to be a lot of muck in there though as the sealing on the caliper piston is on the seal that is usually much further towards the mouth of the piston sleeve.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I don't think so. A caliper design which permitted a bottomed piston to obstruct fluid flow would be a poor design, indeed.

Okay, more info. There seems to be an intermitent vac leak, too. Could that be the seal between the booster and MC? Could that have been the problem all along?
The reason for the replacement is that the car would creep forward at a stop. I would have to pump up the brakes at a stop and the pedal would slowly go to the floor. I had no fluid leak and the res stayed full in all sections. General consensus was a new MC was needed. I got a working used one from Vtech.

I took off the old, put on the new one without bench bleeding it. I bled the back wheels with no problem and nothing coming from the front bleed screws.

This morning I took off the res, bled the MC while on the car and replaced the res. Filled it up, kept it totally full while rebleeding the backs. Nothing in the fronts.

Meanwhile, I now have a vac leak. The car no longer stops right when the key is turned off. It stays running for 2-3 seconds before stalling. I thought I'd found and fixed the leak, a line that went from the booster to the engine, used a hose clamp to keep it on the tube coming from the engine. Doesn't seem to be that, as it still has the leak. I followed each and every vac line under the hood and found nothing loose or off anything. I'm frustrated.


Could it be something like the seals that hold the res to the MC are off center and keeping the fluid from going down into the MC? I couldn't get the res on the MC with the seals on the res, so I put the seals on the MC and pushed the res onto the MC that way. Could that be a problem?

Thanks!
Ginny

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Ginny in Denver-ish
78 300SD, 265K (mine)

Replace the brake line? How the do I do that?
Does that mean i'd have to get UNDER the car? I don't do that. Claustrophobia.
5000# over top of me is not going to happen.

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Ginny in Denver-ish
78 300SD, 265K (mine)

Vacuum has nothing whatsoever to do with the hydraulic portion of the brake system.

The flex line (hose) is located entirely in the fender well.

The thing about it that no one seems to get is that BOTH SIDES in the front have nothing coming out. I took both front wheel bleed screws out and getting zero fluid out of both sides. Neither side is giving me even drips.

Which makes me wonder if there is something wrong with how I put the res on the MC. Could the rubber seals that go on the two feet/holes that feed the fluid into the MC be the problem? The holes into the MC are very small and located at the sides of the well. Could the seal be blocking the hole to the front wheels?

I put the seals in the MC and then snapped the res onto the MC. Should I have put the seals on the res and then put the res on the MC?

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Ginny in Denver-ish
78 300SD, 265K (mine)

You can see if fluid is going thru the MC by just cracking the front brake line right at the reservoir and seeing if it leaks fluid when you press on the brakes. If it does, fluid is going thru the MC. tighten the line before letting up on the brake.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

you do not have to get under the car to replace the brake lines. if you remove the tire, you can see the rubber brake line coming from the caliper to the metal tubes coming from the MC.

if the rubber brake lines are original or the car has been sitting for a while, that is most likely the culprit.

I strongly recommend spraying the nuts with WD40 (or similar) before loosening. Also, you should try to use a crescent wrench (not just a regular open end wrench) to loosen the nut to avoid rounding it. i has been on there for a while and will be reluctant to move.

keep us posted

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Ben
1987 190d 2.5Turbo

Are you 100% sure that the rear chamber of the reservoir is filling with brake fluid? Can you see fluid in both chambers?