My old MC went out about two years ago. I looked at replacement options, saw the Metalli version at $27 and said, "Well, it's cheap. Master cylinders are easy to replace. It's worth taking a chance." So I bought it. Fast forward two years or so to present day. I started up my rig to go to work and found the brake warning light on. The brakes still worked, so I decided to continue on and check into it later. After work, I went by my preferred fuel supplier for a tank of B20 and checked under the hood while the fuel went in. Brake fluid low. No signs of an external leak. I expect I'll find the missing fluid hanging out in the brake booster when I get the MC off. I'll be going upmarket a little with the next MC.

Questions:

1. What brands of master cylinder is everyone running?

2. How to clean brake fluid out of a brake booster?

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I would go OEM,because mine is 32 years old.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran

I've got ATE on two cars. Good stuff.

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Have you checked the condition of the brake pads first? I wouldn't be quick to name the master cylinder as the culprit. You could have worn brake pads allowing the caliper pistons to be out enough to lower the fluid level in the reservoir.

__________________
1983 123.133 California
- GreaseCar Veg System

I put an MC from Autozone on both my 84 & 85 W123, maybe 2-4 years and no issues. I vaguely recall Febi brand. Cost ~$45 and came w/o reservoir. I found brake fluid in both boosters, and had to repaint them. I have DOT 5 fluid in both now so no more paint removal and rust.

Pads, rotors, and calipers are new as of last month.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Was it a new Metalli or a rebuilt one? When I ask the sellers on ebay that sold Metalli MCs they said they were made in Italy.

I put on a new New Master Cylinder Autozone a Fenco NM52326 Made in Taiwan (no ABS on my car) back in I think it was 2008 with no issues so far. Note that FENCO also Sells rebuilt MCs. Mine was new and about $42 but since that time the price on them has gone up or at least it was a few Years ago.

If if is leaking from the Rear there is a Plug with a hole in the Center. The center is where the end of the Piston Passes through and where the Rod goes.
The Plug OD has a regular O-ring on it but on the inwardf side of the Plug is a Seal that Seals the Piston. That is if the Metalli innards are the same as the originals.

__________________
84 300D, 82 Volvo 244Gl Diesel

Looks like the master isn't at fault. I'm having transient clutch issues and I suspect the slave cylinder. It's nine years old and on it's second car. I still need to investigate further to confirm. Having a rather bad oil leak from the valve cover isn't helping either.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.