Our W140 600 series has probable low brake pedal/master cylinder problems

Has anyone had a master cylinder problem with a 600 series W140. We have replaced our prized 93 600SEL brake hoses, new rotors and pads front and rear, calibers are ok, and fluid flushed several times, all by repair shop. still have soft and low brake pedal. We have ordered and repair shop now has in hand a new master cylinder costing well over $1000. We hope this will fix the low brake pedeal problem.
Any thoughts? thanks. Bill & Monika Mercer

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Bill & Monika Mercer

A low or "soft" brake pedal isn't abnormal on the V8 & V12 W140 chassis as they have a SPECIAL solenoid on the master cylinder. That solenoid changes the proportion % of the brake fluid flow to the rear brakes. Going straight the rears get 37% of the pressure & in a corner that changes to 28% (like most other MB's). IF you think the pedal is going to the floor have someone depress the pedal & put your hand between the pedal & the carpet to see if there is any travel left. THERE is a big "hump" in the carpet that makes you think the pedal is too LOW!
Have replaced several $1,500. master cylinders on those cars with NO change in pedal position!

HAVE the brakes been bleed with the solenoid activated?

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

i know it's possible-'cause everything is-to activate the solenoid and bleed brakes at home?

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'95 s500 (bought for wife but can't bear to share!!!) 125kms
'92 legend 180kms
'88 tbirdturbo(fantastic car-only regular maint.)120kms
'87 mustang gt(gone)
'86 tbirdturbo(gone)
'85 mustang gt(gone-but not forgotten)

many thanks, will try and stop the msrt cyl rplcmnt in the shop, what you indicate seems technically right and I will pursue that.
thanks

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Bill & Monika Mercer