Master Cylinder Question

[1988325e]

New member to the site.
Great info!


I have a stock 1988 325e.
The brake fluid has not been replaced in some time and i found rust or what appears to be rust in the fluid.


I removed the brake fluid reservoir to clean it out and also removed the reservoir to master cylinder rubber seals.


I found a round flat metal plate (with a hole) in the front master cylinder inlet port. The rear port did not have a metal plate.


Am i missing a metal plate for the rear master cylinder inlet port?


Also, what is the correct position of the metal plate? There is a tab on the bottom of the port that prevents the metal plate from sitting flat.


Any and all help will be appreciated.

[jeffnhiscars]

If your brakes worked at all leave the master cylinder alone and flush the entire system with new fluid. Brake fluid absorbs moisture and is a 2 year change interval. If neglected your calipers will get gummed up and the pistons will become sluggish. Let's not talk about rust.

I wouldn't be surprised if your bleeders are plugged in which case you should rebuild them all.