There's a brake fluid leak coming from somewhere, I'm not sure why it's leaking but I popped the hood and there's discoloration all over the brake fluid reservoir and you can see moisture around the filler cap. Upon opening it there's a rubber gasket that is just sitting inside the hole not attached to the filler cap, is that causing the leak or has the plastic reservoir just gotten old. There also seems to be some fluid on the master cylinder.

Do I need a new reservoir?

 

Was there brake work done recently? If the master was full and the brake pistons were pushed in when replacing pads, the master could overflow. What is the level of the master now? I think I'd make sure the gasket was in its proper place, tighten the lid, and push on the brakes or take it for a drive then check the top of the master again. Make sure you've wiped off the master before you drive it so any leakage you see is new.

 

The previous owner had new pads and rotors put on all around, I've had the car for 8 months.

As for the rubber gasket, I'm not even sure where that's supposed to go. I think it belongs on the cap, but it's completely loose it was never stuck to it.

I wiped it down, and you can see fluid surrounding the cap and on the sides of the reservoir where the plastic is molded together.

 

I just checked mine and there is a gasket/diaphragm that resides in the cap. Could yours have split? I wouldn't say the reservoir has failed just because you see fluid- it's really hard to get rid of all of it with just a wipe down. You may want to clean the seams with a bit of water on a paper towel or use Q-Tips to get it all out.

 

I’d spray some degreaser and hose it down/clean the area well...

helps with finding the source of the leak sometimes

was the res overfilled or were you doing any break work?

 

I haven't touched the brakes since working on the car, but I think the reservoir was definitely overfilled because the fluid sits like right at the bottom of the reservoir mouth. The plastic is pretty stained so it's hard to see fluid level from the outside, if at all.

Edit: If it was overfilled, then wouldn't it have stopped leaking by now since the excess drained out? I'll check the level again.

 

You should just need a new cap. The rubber gasket is supposed to be attached to the cap. Mine separated in the past year and leaked as well. A new cap fixed it for me.

 

Ah good tip, mine also separated. Good to know that it should be attached to the cap.

 

Please look on the side of the reservoir. There's a "Max" and a "Min" level line. The fluid should be no higher than the mid-point. Get a turkey baster and siphn some out. Be careful...It "eats" paint.

 

Yes, and max is there for a reason. Don't go above it or you may force some out of the lid. I had that happen on my Porsche GT4. My mini reservoir will always seem to have some small bit of fluid around the lid. My rubber seal inside the cap is fine though.

 

Yeah, turned out it was just the cap that was bad - the little rubber gasket was totally broken and the new cap fixed it. No fluid leaking now.

 

Sorry to bring up an old thread and for the possibility of thread jacking. I looked at a R53 I want to buy that seems to have the same leak. My question is, is the worst case scenario just needing to replace the reservoir and or cylinder and then bleed? if so, is that a difficult job?

 

I can't speak to the difficulty of replacing the brake fluid reservoir / master cylinder, luckily the leaking was simply due to the bad fluid cap. See if you can check that out first, if you can pull the rubber gasket off the cap then it's bad.

 

I am in NY - owned the r53 from day 1. Last year @ 140k, he started losing brake fluid. I thought it was the master. I replaced that - not a bad job. Just be sure to use line wrenches on the connections. The real issue was traced to a rusted line to the left rear. It was leaking mid way - I replaced it with a copper line ( look up American Grease Stick ). Bleeding was not bad - a lot of air came out.

 

Thanks for the response. Hopefully it's just a bad rubber gasket.

 

Thanks for the response. This makes me feel a bit more at ease knowing that it is not a super complicated job, that is if it is not just a rubber gasket.

 

I replaced my master cylinder recently and it’s not bad at all, I think there’s a good diy either on here or at pelican parts.com bleeding it isn’t bad either. I recently bought a motive power bleeder and it makes bleeding the brakes a pretty easy 1 man job. I highly recommend it. Personally I just use it to pressurize the system and only put brake fluid in the reservoir, it cuts down on the mess and wasted brake fluid which is nice when your brake fluid costs $40/quart….

 

oh thank for the link. I have a power bleeder, so bleeding should be ok. the steps looks simple enough. thanks again.