300E Rear Brake Failure

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goofy871@gmail.com - 14 Nov 2005 05:22 GMT

Hi,

i was changing my brake pads on my 300E 1989, and when i got to the
rear, i couldn't get the pistons to go in because they were stuck.
When i asked the NAPA guy what to do, he asked me if i had taken the
caliper off yet. I decided to go home, and see if i could get it off,
but i removed the wrong bolts, and opened the caliper. My pedal was
then low, so i bled the brakes. This did not help. I replaced the
rear calipers, and bled for hours. No fluid was coming out, and they
are not engaging. Does anyone know what could have gone wrong.

Thanks in advance for any help

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T.G. Lambach - 14 Nov 2005 06:09 GMT

Does this car have ABS brakes?

Before attacking the rear calipers what was done to the front brakes?
Did you bleed the front calipers?
After the front brakes were reassembled did you drive the car?

Now to the rear.
The rear caliper pistons were stuck.
You mistakenly opened? the caliper's bleeder?
You removed the rear calipers from the car? If so, did you remount each
to its respective side? L to L, R to R?
When you bled the brakes did you refill the master cylinder with DOT 3
or 4 Brake fluid?
When you bled the caliper, someone pushed the brake pedal while you
opened and closed the bleeder or did you open it and leave to pump the
brake pedal?
What about the stuck rear pistons? Are they still stuck?

So now the rear brakes are reassembled but there are no brakes because
the brake pedal sinks to the floor?

I once installed the left side caliber on the right wheel and the right
onto the left. They fit but I couldn't figure out why bleeding wouldn't
firm the brake pedal. My boss saw my error had put the bleed screws onto
the calipers' bottom side - of course air is lighter than fluid so it
was trapped in the caliper's upper section and would still be there but
for him!

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goofy871@gmail.com - 15 Nov 2005 02:01 GMT

My front pads had already been changed, without any problem. When those
are bled, the pedal sinks to the floor, and when you finnish the pedal
is firm until the car is turned on. When i put the new calipers on, my
dad sat in the car and pushed the pedal down and held it while i opened
and closed the bleeder. I had the cap off the resevoir and topped off
w/ dot 3 brake fluid. The front brakes work, but the rear do not

I took a jar and filled it w/ brake fluid, and stuck it down in there.
My dad and i pumped the pedal, and when we did air and dirt was coming
out. But when we tried it without being in the fluid, no fluid came
out of the hose.

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T.G. Lambach - 15 Nov 2005 02:24 GMT

"When those (front calipers) are bled, the pedal sinks to the floor, and when you finish the pedal is firm until the car is turned on."

And then, when the engine is running and its vacuum hits the brake booster, what happens?
Brake pedal sinks to floor or "normal"? (Still on the front brakes here.)

You bought new / rebuilt calipers for the rear brakes and mounted them.

Now you can't get them bled, in fact no fluid comes out of these
calipers' bleeders when you press the brake pedal UNLESS the bleed hose
is hanging into a jar of brake fluid?

That's strange. What's the brake pedal doing then? Very firm or on the
floor?

You should know that without the engine's vacuum the physical effort to
brake is quite high and the car's reserve vacuum is exhausted after
about three "stops". Start the engine for a half minute or so to rebuild
the vacuum in the reservoir and then try to bleed the rear brakes.

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