Skoda Fabia I (LHD) 2001 model with 124.000km on the clock.

1,4 8V 50kW (engine code AQW)

ABS, with brake servo

The past weeks I've had to top up the brake fluid reservoir twice, something that should ring every car-owner's alarm bells. At the moment, I've already had to dump in 0.5 Liters. I'm very cautious and looking for leaks all the time, but too stupid to stop driving, so I have to fix this fast.

I've visited some workshops but I none have time within a week, so I started looking for a solution myself.

There have been no apparent leaks under the car, so it must leak somewhere inside the car. And so I found it in the pedal box. It's not exactly squirting out, but it is obviously leaking:

I immediately concluded a broken brake master cylinder so I started an order process for it and it seems like I could have one in my hands within 2 days.

But then I suddenly realised that I have a brake servo. How could fluid be leaking through the servo, which is supposed to have a membrane in it that should in theory prevent oil from going though?

I can confirm that the brake servo is working, as the pedal sinks when turning on the engine with a pumped up pedal.

Let me point out that the clutch cylinder and pedal are completely clean, no leak there.

Am I looking at replacing BOTH the master cylinder as well as the brake servo?

Edited 14 November, 201213 yr by JvdP

test for leaks through servo ( usual cause is failure of master cylinder seal). Drive down road and hit brakes(HARD) a few times. Come to stop, and drive of. Look for plumes of white smoke behind. Brake fluid getting into cylinderswill burn white . Don't know if it's possible on Skoda. I found this on an ancient Vauxhall. I doubt if the servo is at fault- simple to test - try braking with engine on and off , with servo reeservoir empty. Could be a non serious rupture in any membarne in the servo .

Just a few thought from someone whos had a master cylinder leak into the servo.

I can't see your picture but is it possible it's not a leak but some kind of lubrication, or someone trying to fix a squeaking pedal? I'm assuming your car has rear drum brakes. It is possible for a wheel cylinder to leak a fair amount of fluid in the drums and all over the shoes before in becomes overly obvious from the outside.

Good call on the wheel cylinder ^^ I over looked that when reading this thread earlier. Somthing to look into.

Good call on the wheel cylinder ^^ I over looked that when reading this thread earlier. Somthing to look into.

And cheaper to check this first before replacing a master cylinder/servo. Fairly common for a wheel cylinder to fail at that sort of age/mileage I'd say.

I've now also attached the photo so you can see the 'leakage'. I've never looked down there before so I don't know since when it's there. But it doesn't smell and it feels much like brake fluid but I'm not sure.

I will see if I can unmount the back wheels to check the wheel cylinder. This should be visible after disassembling the wheel and then the cylinder, right?

test for leaks through servo ( usual cause is failure of master cylinder seal). Drive down road and hit brakes(HARD) a few times. Come to stop, and drive of. Look for plumes of white smoke behind. Brake fluid getting into cylinderswill burn white . Don't know if it's possible on Skoda. I found this on an ancient Vauxhall. I doubt if the servo is at fault- simple to test - try braking with engine on and off , with servo reeservoir empty. Could be a non serious rupture in any membarne in the servo .

Just a few thought from someone whos had a master cylinder leak into the servo.

I must thank you, because you were right. I have a leak at the wheel cylinder back... Saves me stressing about changing the master cylinder and servo.

This doesn't explain the small leak of some sort of fluid from the pedal box though, but this worries me much less at the moment.

If the layout on the rear drum is the same as on mine,I found it usefull to hold the top spring in position with a bit of wire (stops it falling out) whilst assembling the rest . Then after fitting the adjuster, remove the wire and replace drum .