two left feet

Well in my case, not enough.

I noticed the brake pressure warning light (C4) indicating either that the pressure assit was malfuntioning, low or the brake oil level was low.

Of course I checked the oil level - right on the low limit! After a top up, warning light goes off, everything normal

I then had the thought "have I got a leak or where did the oil go" ? It was explained to me that as the brake pads wear, so the caliper pistons must move closer to the disk and so increase the fluid path. Oil not used, just more oil needed.

As we (me anyways) tend to look for the exotic causes for errors, it just shows that a little regular "house keeping" is maybe all that is needed. I hope this helps someone......

914und993

Actually, it might not be so simple for you. Its pretty unusual for brake fluid to just disappear without there being a leak somewere down the line. I think I would start looking pretty hard for that leak.

Chip

mike cap

Andrew,

Chip is right. I'd watch the brake fluid carefully. I've seen cars with the brake pads worn down to the back plates and the brake fluid level was still nearly full.

Ron

Andrew,

On occasion brake fluid will just disappear from the reservior without any apparent leak downstream. Fluid sometimes, not real often, can leak into the brake servo and be sucked thru a vaccum line. If you can not find a leak and you are losing fluid it's a good chance that would be where the fluid would be going.

Robin 993DX

In normal usage the reservior level will go down just from normal brake pad wear, as the brake pad wears out the caliper piston have to extend further which creates more space needed to be filled by the brake fluid. That's why sometime you will need to add brake fluids to the reservior, that's why sometimes when you replace the brake pads you will get fluids that overflows the reservior as the brake caliper piston is now pushed back.

It is possible that your fluid level was low from the start, and as the brake pads wears down it happends to trigger the low level warning.

two left feet

Hi Guys,

Did spend alot of time in the shop and at my request spent time looking for the leak - nothing obvious - the blue racing fluid is easy to see.

The explanation sounded logical to me at the time, and it had been 6 months since a had new pads and big reds installed.... again shame on me for not checking.

two left feet

It is quite possible that the level was on the low side, but I can not say for sure as I didnt check it immediately after the big reds were installed.

Based on my quite rusty maths, the oil level must have been near the limit to start with. If for instance the pads wore by 5mm, based on 4 pistons per caliper with radius of 20 mm each, the extra volume of oil would be ca 100 cc.

Q.E.D ? or is my math too rusty...

viperbob

OK, so with this knowledge of where the fluid goes, did you check your brake pads for wear? Just turning off the low fluid light does not make the brakes work better if your pads are shot. Many cars have had their wear sensors disconnected, so waiting for this light may not be the proper thing to do.

If you just recently installed Big Reds, then more than likely when they were installed someone bled the brakes and topped up the brake fluid. But then when you go and turn on the car, your fluid disappears out of the reservoir (into the ABS pump). You should check the archives as if this is the case, then your system may not have been properly bled and you could have air in the system....

Travis

...or in my case, I had a leaking clutch slave cylinder that was the cause of brake fluid loss.

Didn't see any drops on the ground, but after taking the transmission shield off, it was obvious where all the fluid escaped from.

Since changing the clutch slave, no more leaks!

hope that helps,

-travis