While bleeding brakes, the pump monkey said the pedal went straight to the floor without me opening bleeder valve. I opened up the bleeder valve while pedal was down and fluid, which had been spurting out, was now barely a trickle. I got in the car and pushed the pedal several times. Pedal goes straight to the floor with little resisitance. I can hear fluid swooshing around in the master cylinder. I don't see any leaks. Does this sound like problem with master cylinder, vaccum booster or both? Shouldn't the pedal get really stiff and not go down at all after pumping the brakes several times with the enigne off if the vaccum booster is okay?

Do you have fluid in the reservoirs ????????????

__________________
A Dalton

One of the reservoirs MB uses camouflages the rear fluid level. It is actually surrounded by the front fluid and the rear chamber goes empty without being noticed. If you remove the cap and the black rubber fluid guide one can see the empty chamber.

If that isn't the issue, the other thing that happens is that bleeding procedures state to not fully depress the pedal when open. When the piston seal is driven into the muck at the bottom of the bore it can easily never seal again.

The issue is in the master cylinder not the booster.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

If your master cylinder is pumping fluid into the booster, you need to clean it out ASAP or it will deteriorate.

You won't feel the effect of the booster unless the car is running to give it vacuum.

Remember the bleed order: R/R, L/R, R/F, L/F

I recently bled mine and the pedal didn't really start to firm up until we started on the front passenger caliper.

__________________
Chad
2006 Nissan Pathfinder LE
1998 Acura 3.0 CL
OBK#44
"Pleasure in the job puts perfection in the work." - Aristotle (384-322 B.C.)

SOLD
1985 300TD - Red Dragon
1986 300SDL - Coda
1991 - 300TE
1995 - E320
1985 300CD - Gladys

As far as I see the reservoir is full all around.

As we posted, there are 2 reservoirs....one for the front and one for the back.
Take the top off and you will see there is a wall in between the two reservoirs...so you have to fill it right to the top for the fluid to go over the wall and fill the other one..otherwise, you are pumping air and wasting your time.
Look in there real close b/c you can not see the other chamber from the outside.
That is what was meant by " camouflages " and that is why I posted "reservoirs " ..in Plural.
Check it out closer and I think you will see what we mean.

__________________
A Dalton

Have never seen a brake bleed order before. From where did this information come? Does this include all MBs?

The order is bleeding the furthest point first and working back. It doesn't matter on cars with ABS, although it is still recommended to do the passenger side first.

__________________
Chad
2006 Nissan Pathfinder LE
1998 Acura 3.0 CL
OBK#44
"Pleasure in the job puts perfection in the work." - Aristotle (384-322 B.C.)

SOLD
1985 300TD - Red Dragon
1986 300SDL - Coda
1991 - 300TE
1995 - E320
1985 300CD - Gladys

I'll check it again, but I filled to the very top of the spout as I bled.

I removed the master cylinder. Manually pumping it, fluid squirts out of the rear connection (front brakes?), but the fluid barely comes out of the front connection (rear brakes?). So I guess this means that "seal" is bad. I've ordered a new MC which I will be installing on the car. BTW, while I realize you guy's wouldn't put a rebuilt MC on your car, does anyone sell a kit for rebuilding these (1991 190E 2.6)?

THANKS!

get a pressure bleeder - you can make your own (a quick search will show all you need)

i had the same problem - once i did the process with the pressure bleeder, pedal returned to normal

Pressure bleeders are great! It's nice to be able to bleed the brakes by yourself.

You need to have a turkey baster or a fluid extractor to remove the excess fluid down to the max level line after the bleed or flush is done.

__________________
Chad
2006 Nissan Pathfinder LE
1998 Acura 3.0 CL
OBK#44
"Pleasure in the job puts perfection in the work." - Aristotle (384-322 B.C.)

SOLD
1985 300TD - Red Dragon
1986 300SDL - Coda
1991 - 300TE
1995 - E320
1985 300CD - Gladys

Best $20 i ever spent - and easy - i tried to bleed with my son and the old fashion method - took 2 hours

Did it with the prower bleeder last night - took 20 minutes

I thought the parts for this were at least $40.00! Can you give me more info on the $20.00 power beeder?

Sorry my bad total is $26.57

Sprayer: $12.99 (ACE)
Master cyl. cap $3.99 (Pep Boys)
1/4" brass fitting $1.24 (Lowes)
1/4" brass fitting $1.27 (Lowes)
Vinyl Tubing 1/4 ID $1.82 (Lowes)
O'ring pack $1.27 (Lowes)
Air pressure guage $3.99 (AutoZone)

Also figure on 1 1/2 liters of brake fluid

Either way still cheaper than buying one - and me and my son had fun doing it to boot