Brake fluid overflow

[inquirer]

The cap is not air tight. It allows air in so that the membrane can get sucked in as the brake fluid drops with pad wear. Since the brake fluid flowed in reverse, it leaked past the membrane as it is not designed to keep hydraulic pressure.

Can this damage the membrane though? Should the cap get replaced after an overflow?

I only top up brake fluid when I put new pads on on my own car

I usually do that too, but this time I had changed the brake hoses with braided ones and I changed the fluid along with them.

 

[barryh]

i wouldnt be a bad idea when compressing piston ,to run that fluid out of the bleeder , get that nasty stuff out of there

This is how I do it.

Forcing dirty fluid from the caliper back up through the system is not a great idea. Better to open the bleed nipple and let the displaced fluid flow out into a jar.

 

[ordinarybloke]

You're bound to spill fluid doing a brake-job. Don't leave it long. Throw a jug of water over the offending area pretty quick and you're fine. Careful though, many MC caps have a breather-hole, don't be chucking water at that.

 

[inquirer]

You're bound to spill fluid doing a brake-job. Don't leave it long. Throw a jug of water over the offending area pretty quick and you're fine. Careful though, many MC caps have a breather-hole, don't be chucking water at that.

How long is too long? I used plenty of water, but only after I lowered the vehicle to the ground. I guess it took me around 15 minutes to brush the caliper, install the pads and finally to reinstall the wheel.

The cap has no hole. It has a membrane though and a groove that I guess is the way out for the fluid if an overflow occurs. I am wondering if the membrane is designed to allow an overflow to take place or if the cap should get replaced after an overflow.