1982 240d rear brake problem

[Alaska240D]

I recently bought a 240d with a lot of delayed maintenance. At least one rear brake was not working. I replaced both rear calipers, pads and bled them quite a bit two different times. Pumping the brakes sends brake fluid out the bleeder however apparently not enough to lock up the brakes. What should I do next? Master cylinder?

You should flush the system with a bottle or two of fresh fluid first. Then, the MC.

How well does the car stop?

[toomany MBZ]

Yes, the brakes won't lock up when bleeding.
Good on the replacing calipers, test drive, and compare to previous brake feel, stopping power.

[t walgamuth]

I don't understand your problem. when bleeding them why would you try to lock them up. I think maybe you are not bleeding them correctly. In any case if you have a good firm brake pedal you are fine.

Tom W

I think he means they are receiving fluid while bleeding but they are not getting any pressure to stop the wheels when he is not bleeding them.

[JimFreeh]

Originally Posted by ForcedInduction

I think he means they are receiving fluid while bleeding but they are not getting any pressure to stop the wheels when he is not bleeding them.

This can happen if the master cylinder runs out of fluid while bleeding, and you can get an air bubble. Might need to pull the lines at the MC and "bench bleed" the master.

Jim

[vstech]

this sounds like you have plugged lines, or damaged flexible lines. I would pull the flex lines and replace them.

[Skippy]

I second replacing the soft lines. I did mine when I rebuilt the brakes on my '83. The hoses were like ten bucks apiece at NAPA and only added a few minutes to the total job.

If new hoses followed by a thorough bleed don't help, then it might be master cylinder time.

[Alaska240D]

The bleeders on the ATE rear calipers are on the bottom.
New brake lines have been ordered. The old ones are not kinked.
The brake pedal is firm when pressed. The front brakes work fine.
I allowed each caliper (one at a time) to drip bleed about 20 minutes each last night and I did not test the rear brakes yet.
How should I diagnos a malfunctioning master cylinder?

[tangofox007]

Originally Posted by Alaska240D

The bleeders on the ATE rear calipers are on the bottom.

I thought that might be the case. It's hard to bleed the air out of the caliper with the valves on the bottom.

Originally Posted by Alaska240D

How should I diagnos a malfunctioning master cylinder?

Typically, a leaking m/c will allow the brake pedal to go the the floor if pressure is applied continuously.

[P.E.Haiges]

Alaska,

The bleed screws have to be on the top to get the air out of the calipers. Sounds like U reversed the R and L calipers .

Reverse them again and see if your problem goes away. If problem goes away, hit your self in the head with a hammer so U remember to never do that again. LOL

P E H

[Alaska240D]

I had installed the calipers in reverse. It is quite a relief to have the brakes working without buying parts needlessly. No need to hit my head with a hammer, my self inflicted mental abuse and this humiliation is enough.
Thank-you again. I would never have figured this out.

[P.E.Haiges]

ALaska,

Were the original calipers reversed too? If they were, U probably wouldn't have had to replace them.

I could see that if the original calipers were reversed it would be logical to install the replacement calipers reversed, so I will take back the hammer comment. Its the guy that reversed the calipers the first time that was the ducking fummy.

P E H

[Alaska240D]

I thought that I replaced the calipers the same way I took them off but I didn't take a digital photo to be sure. One caliper had an unworn brake pad and the other was very worn. The calipers appeared to be in bad condition and the inside area that moves had deteriorated seals or whatever. I will take more pictures before I remove things to make sure they go back as removed.

I still have a lot of things to repair. I will be adjusting the valves and changing the transmission fluid/filter once I get the center console back together and more parts arrive.

[P.E.Haiges]

Alaska,

OK, sounds like the original calipers were bad. I would have rebuilt the calipers.

Keep the old pads, they might come in handy some time.

P E H