Master Cylinder Bench Bleeding

Started by dubstar, July 21, 2013, 05:58:31 PM

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dubstar

I have just got the golf on all fours and taken it for a test drive.  When the engine is off, 2 pumps of the brake pedal leads to a solid pedal.  With the engine running, the pedal sinks to the floor and I only get 'braking' at the very end of the pedal movement.

This probably shows I have air in the master cylinder still........

I am using my power bleeder and, on my 2 previous master cylinder changes, I never had to bench bleed the m/cyl.  Any tricks to getting air out while in the car? 

I have heard you can pressurise the system with the power bleeder, crack open a nipple and then depress the pedal a couple of times.......

For those, who haven't read my build thread, I have new brakes all round and a new booster/master.
"I am so clever that sometimes I don't understand a single word of what I am saying."

Gordo

I don't know about your specific car, but some others can be a ***** to bleed due to their pressure limiting valves - some have even had bleeders at the valves.
Other thing may be the master cylinder sealinf rubber and/or bore is faulty - under high pedal forces it may seal OK but ligher forces the seal may not seal against the bore properly.

All I do is use a check valve type bleeder and go round the wheels in turn. Worked 100% so far, even on cars with limiting valves - but I may just be lucky.
These are my thoughts and opinions - sometimes I'm wrong, but not often ;-)