1991 Q45 - Rebuilding Master Cylinder - How Much Brake Fluid is Required?

[lino]

I'm having my Master Cylinder rebuilt tomorrow and was wondering how much brake fluid I'll need. I'm not flushing entire system, simply replacing whatever fluid is lost during the process.

[maxnix]

Not replacing the hygroscopic brake fluid in its entirety after being exposed to air is extremely unwise!

[lino]

I have to replace the front rotors and pads and the rear rotors and pads. I'm preparing for it right now. Hopefully I'll be able to do that in a few weeks. The master cylinder is being rebuilt now. I have to do my work in installments.

[maxnix]

Then a single can should do it.

But don't delay replacing it.

[bullittandy]

I don't know how you could repair/replace the master cylinder without flushing the system. I mean you have to remove lines and what not which will open the system introducing air.

Am I missing something?

[lino]

Then a single can should do it.

But don't delay replacing it.

Thanks Brian. I have 1 unopened 12oz bottle and 1/2 of a 12oz bottle that I bought a month ago. The place that I buy the brake fluid from is sold out of the Valvoline synthetic that I use and is the only place here that sells it. I don't want to mix fluids and don't want to lose my appointment for tomorrow.

[lino]

My mechanic removed my master cylinder to rebuild it only to discover the kit I bought from the dealer (Part number 46011-60U86) was the wrong one. The pistons were too big and did not go in. FAST says that's the correct part number and so did the dealer. Fortunately for me, it turns out that my master cylinder was working fine and it didn't need to be rebuilt. I decided to rebuild it because I had noticed that my fluid level had gone done a bit and thought maybe it was on its way out. Anyway, its fine now and I'm still trying to figure out why the kit was the wrong one. My car was built in the 10th month of 1990.

You were right Brian . I didn't need very much fluid at all and it only took 5 minutes to bleed the system.

Anyone know why the rebuild kit was the wrong one?
Modified by lino at 3:52 PM 5/18/2009