E30 Brake fluid on carpet

May 01, 2006 11 Replies

I've got a 1990 BMW 325i convertible that I bought about a month ago.. Brake fluid light came on a couple of weeks ago so I put some brake fluid in. Today the light came on again. So I put some more in. Drove about five miles and had brake fluid on the carpet on the driver's side. How did this happen? Can someone tell me what may be wrong?



Thanks



"nichdl1" wrote

Your master cylinder has failed, and is leaking fluid. You need to get it replaced ASAP. It's an easy DIY job, but you don't seem like a DIY guy, so head to a brake shop.

FloydR

How hard a job is it? and why does it leak on the carpet?

Will it continue to leak if I don't drive it? My mechanic is booked until next week.

"nichdl1" wrote

The hardest part is bleeding the system afterwards - usually a two-person job (not hard, just tedious).

It leaks onto the carpet because the shaft that drives the piston goes through the firewall. The piston's seal is leaking, and it goes back along the shaft through the firewall.

It won't leak if it's not driven.

FloydR

If you do much DIY on brakes - including routine fluid changes - it's well worth getting a pressure bleeding set. Not expensive - they use air pressure from your spare wheel. Makes it an easy one man job, and far quicker than manual bleeding.

You have to take care when assembling them to make sure you have no leaks

- otherwise brake fluid can go everywhere. But not a problem with care. ;-)

It is a 5 speed and I now suspect the clutch slave cylinder may be at fault. My mechanic had told me it was leaking when I was looking at the car to buy. There is no sign of a leak inside the engine compartment around the master brake cylinder. It is not wet, nothing dripping or any sign of a leak around it. Just the fluid on the floor of the car. Do I need to replace both the clutch slave cylinder and the master brake cylinder? or can I get by with just the clutch slave cylinder (much less expensive)?

"nichdl1" wrote

If you have oil INSIDE the car, it's the Master clutch cylinder that's leaking, not the Slave: a leaking slave - located on the front of the bell housing - would only leak onto the road/garage floor.

FloydR

Both the brake and clutch cylinders as operated by the pedals are known as master cylinders. Slave cylinders are the ones they operate - ie they do what the master says. ;-)

Jeez, I'm glad *somebody* is watching the store! OF COURSE it's the clutch master! The brake master isn't inside! Nor is the clutch slave cylinder, unfortunately for the OP. If the clutch master is leaking, it needs to be replaced. It's not real expensive for the part, but it takes a contortionist to do it. You should be prepared to pay appropriately.

-- C.R. Krieger (Been there; done that)

Jeez, I'm glad *somebody* is watching the store! OF COURSE it's the clutch master! The brake master isn't inside! Nor is the clutch slave cylinder, unfortunately for the OP. If the clutch master is leaking, it needs to be replaced. It's not real expensive for the part, but it takes a contortionist to do it. You should be prepared to pay appropriately.

-- C.R. Krieger (Been there; done that)

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