brake fluid leaking from master cylinder

[Garth]

Opened my bonnet recently to discover brake fluid everywhere. This was not long after my CC service (including brake fluid change) and a track day. Paint work has been damaged. CC's say fluid sometimes leaks from the cap! I did not have any problems before they changed the fluid even on the track. My view is that CC have messed up and I should push for them to sort out the damage?

 

Has anyone else had a similar problem? Thanks

Garth

 

Edited by - Garth on 29 Sep 2012 10:58:47

[Mankee]

They have probably filled it right to the brim with fresh fluid and the heat from the brakes and cornering forces from your recent trackday have thrown the excess everywhere. Did they or you change pads recently as well? I always recheck the level after a pad change or if I've fiddled with the pistons, as the level can change. I've had a similar issue with a leaky cap, but my car is a battered old racer, so I'm not too fussed about the paint. Hope you get a good outcome.

[billyboanerges]

My master cylinder spills fluid if over-filled. I keep it at a level where the warning light just flashes under rapid acceleration, any more fluid and it leaks - maybe the cap.

Tony

[Jason Plato]

or if you cross the threads on the cap....

[Shad]

The AP master cylinder is quite prone to this, best solution is just to keep the level around 5mm above the minimum marker and check regularly. It sounds like CC just over-filled it, unless the seal on your cap has failed.

[wjblundell]

I fitted a race master cylinder cap, Caterham part no. 77175, no more problems. Just remember that the low fluid warning light no longer works and you will need to refit the original for MOT's.

 

[Drumster]

I have the AP master cylinder and the standard cap. I just make sure I don't overfill it, the warning light still works as intended and it has never leaked during any trackdays or sprints. Maybe I'm just lucky......

[IanW]

I had a similar problem with my master cylinder leaking during a track day. I wrapped a cloth around it to stop the fluid spreading any further.

 

I fitted another rubber washer to ensure a good seal and it hasn't leaked since.

 

[Garth]

Thanks for the comments - will check the level again - should be low if they filled it to the correct level given the amount that must have come out! Then a trip back to Dartford to show CC. There were two rubber washers in the cap - I took one out and then Stuart from Premier Power wrapped some tissue around the cap and secured it with a cable tie.

[ParsleyTheLion]

Out of interest - why does this issue seem to be related to the AP master cylinder? Looking at the pictures of the standard part, and the racing part, the plastic tanks seem to be identical parts. So, why would one be more prone to leaking than the other?

 

Or is it just that people with race master cylinders are more likely to go racing?

 

std here AP here

[richy]

Quoting billyboanerges: 

My master cylinder spills fluid if over-filled. I keep it at a level where the warning light just flashes under rapid acceleration, any more fluid and it leaks - maybe the cap.

Tony

Same here - at least the occasional flashinh warning light assures me it's working!

Richy

[Z3MCJez]

Quoting ParsleyTheLion: 

Out of interest - why does this issue seem to be related to the AP master cylinder? Looking at the pictures of the standard part, and the racing part, the plastic tanks seem to be identical parts. So, why would one be more prone to leaking than the other?

 

Or is it just that people with race master cylinders are more likely to go racing?

 

std here AP here

 

Same problem with standard m/c. Even with the race cap. Don't fill to max limit. And wipe often post-fluid change.

 

Jez