Confused about losing Brake Fluid

Hello all. My wifes car sat for a couple of weeks and she went out to drive it. It had no brakes. Thinking there was a problem with the MC, I replaced it. There was no fluid leaking into the booster area from the old one. After it was replaced she would get periodic times I had to add fluid cause the warning light came on. I disconnected and plugged the hose going to the upper back area but that made no change (what does this do anyhow?). Still losing fluid. I've checked around the Master Cyl and can see or find no leakage. I've checked around each of the disk brakes and also cannot find any leakage. If I bleed the brakes it has no bleed down or quishyness. I just cant find where the fluid is going. Idea's ? If the car is driven regularly the issue occurs every couple of weeks. but if it sits for more than a few days it happens very quickly (low fluid level). It's a real head scratcher for me.

Brake fluid is one of the easier leaks to locate. Either a line, caliper or master is leaking.

All of these if leaking externally should leave a puddle somewhere, save a rear seal leak on the MC.

Now, if you replaced the MC, did you see any wetness on the back of the MC where it attaches to the booster?

If not, I would get the car on a hoist, or on stands. Get a partner to press on the brakes hard and inspect underneath where the fluid is going.

Can't recall if any of the lines go inside the car on a 2006, but leaks inside would be rare.

Likely the clutch hydraulics as fluid is supplied from the master. Otherwise you're missing something in the brake system.

If there are no leaks, brakes aren't working and the MC has been replaced I'm thinking booster.

Check the carpet inside driver's foot well. Look and touch upside. Is your clucth master cylinder leaking fluid??

Also, the reservoir is split into two parts. It's designed in such way so that if it leaks fluid, only half of the reservoir fluid will leak out, other will stilll be at minimum mark (the reservoir is split into sections).

So let the fluid leak out completely. Then use a powerful LED torch to shine trhough the reservoir and see which part of it still has got fluid. The brake circuit is spit into two parts - Front Left & Rear Right and Front Right & Rear Left. This will help you nail down which circuit should be extensively checked (assuming it's not the clutch system which is leaking your fluid)

Hello everyone. So, after chasing this... I found my leak. The interesting thing is that it only leaked when the e-brake is applied. This is why when it sat for a few days without being driven it would run out of fluid. Also, the leak being way behind the caliper where the ebrake arm goes into the back of the caliper it was difficult to see it. It also did not leak under pressure when the ebrake was off. Was an interesting one to find as I had my wife standing on that brake pedal and no leaks, she got tired I sent her into the house and applied the ebrake and just sitting there it starts dripping with no pressure. Crazy. But, peace of mind now. I'll replace that caliper and we should be all good.

Thanks for the suggestions guys.

There's always a puddle somewhere...

Glad you found it.

Ryan_B said:

Hello everyone. So, after chasing this... I found my leak. The interesting thing is that it only leaked when the e-brake is applied. This is why when it sat for a few days without being driven it would run out of fluid.

Click to expand...

I think I might have this exact same problem. I was just away on a work trip for a little over a week, and had to leave my car at one of our offices up north. When we got back, my coworker asked me if my car was leaking something as there was some staining on the pavement. It was hard to see as the pavement was already wet anyway, but it was quickly confirmed when I got in the car and the brake pedal went to the floor and the light on the dash was flashing.

The brakes were perfectly fine when I parked the car there the week before. Anyway, I drove it back like that and dropped it off at the VW shop late last night. Should hear back on Monday, but it sure sounds like the same problem you had here.

Rear caliper leaking

Just to add an update to this post. I thought I could see my caliper leaking at the emergency brake mechanism from a quick glance while the car was on the ground. So I picked up the caliper and replaced it. Turns out it was the brake line. I think it was probably where the plastic hose is connected to the metal mounting block for the caliper. It was not the plastic portion of the hose that was leaking! It was a bit of a mystery!