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Discussion Starter #1
1991 300e 3.0:


Does this pictured loose/dislodged pin and washer mean that the brake booster is broken?
Or can I put the pin back in place and properly seat the master cylinder onto it?

Thank you,



264 Posts
Discussion Starter #2

Last week, I went to replace a bad master cylinder, and brake fluid flush
When I put the new M/C in place, at first it wouldn't bolt up

Then I jiggled it a little, and nested it into the booster

as I tightened it, I heard a 'clunk', which to me meant it was now seated in place.

fast forward to today

I am going to do a two-man brake fluid flush
I try flushing from the rear right caliper first, working my way to the front.
Fluid is not coming out the nipple

I decide to first flush the new master cylinder.
The rear line flushes properly
The front fluid going through
I thought maybe bad M/C again.

So I remove the master cylinder to bench test it

Then I see the attached pin and "washer" (for lack of a better term)
loose inside the booster

Perhaps the clunk I heard dis-lodged this pin and washer

Premium Member
Current, 90 300CE, 92 400E (Sold 95 E320,70 250C, 91 190 2.6, 91 420 SEL, 95 300D, 87 TD)
1,692 Posts

I have never done this job......yet:unsure:.
But hopefully someone will answer.

I know someone knows!
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