Master cylinder leak

[Wander]

My daughters 04 DII had the brake light come on, fluid was low so I topped it off. Next day noticed a spot in the drive ( also recalled a small spot earlier) so I took it in. No problems or lights on way to shop, got a call that the master was bad, mentioned to them that a more common problem is the seal between the reservoir and master but they replaced the master. Then I get a call the master was leaking into the booster and that is bad, that didn't add up at all as there was no problems with pedal force before I dropped it off. Went to shop, paid the bill so far and brought it home . Sure enough there is no boost now. Was this the shop or does it add up?? Pretty frustrated right now.

 

[EricG]

My 03 leaks a bit seems to be worse when cold. I keep it topped off. I haven't had a brake light.

 

[overlander]

sure sounds like seal leak between reservoir and master. I've replaced that seal before and that was it. This time of year, when the first freezing temps hit, is when the little leaks pop up as rubber seals shrink up, and thus requires things like hose clamps and such to be tightened a turn or two.

As for the boost, check the rubber seal the check valve fits in, and the vacuum line running to the manifold. I seriously doubt a little brake fluid ruined your boost servo.

 

[Wander]

That surprised me as well. I'll check it all out tomorrow he I have some light, it was dark and rainy here all day. Sure enough I had to stand on the brake pedal on the way home. How that suddenly went that bad really has me thinking the shop messed up.

 

[I Leak Oil]

It's not uncommon for the MC to leak into the booster. The fluid then can quickly eat the diaphram material which is not very resistant to brake fluid.