Hi guys, first time to post but have spent plenty of time reading through the forums. I just recently got an 04 L67 from my mother and I'm having to repair a lot of wear and tear, but I'm not a mechanic and this is the first car I've actually done in depth repair and diagnostics on so I need a little help deciding where to start on this problem.

So I've got a bad vacuum leak between my master cylinder and brake booster, my short term trim is maxing out at 20.3%, it will run back to around -3% to 4% if I press the brake pedal all the way to the floor so the leak is definitely in the booster.
Spraying with carb cleaner I've found that the leak is where the MC and booster are bolted and I believe there should be a gasket between the two correct?
My question is mainly if it's just the seal that's broken can I disconnect the MC from the booster without having to disconnect lines and bleeding the system?

Also I recently had a new transmission put in and I read somewhere that the MC has to be removed to replace it? Where I read that was short on information but if that's true then I'm taking it back to the dealership to make them fix it.

Thanks in advance for any help.

 

Its my experience...
That the rubber seal/grommet between the Master Cylinder and the brake booster is where the leak develops...

The only way to fix it...Is to replace the booster... you should be able to unbolt the Master Cylinder from the booster with out disconnecting any lines..(Be cautious as you do this as to not kink any lines)

I don't believe you have to remove the Master Cylinder to do any type of trans repair/replacement...

I'm sure other members will chime in with more info...
Thanks for joining the MCF Family!

 

You can unbolt the Mc without removing the brake lines. And when the trans was replaced if they just dropped the trans out the bottom there is no need to remove the mc. If your pulling the engine and trans both out the top the mc needs to come off. Trans can't come out the top unless engine comes as well.

 

Alright thanks guys, I didn't figure you had to take off the MC for a trans replacement but they had taken my intake off and I wasn't sure if they had pulled other stuff too. They treated me so badly that if they caused anything to go wrong, I'll take it back and make them fix it.

So would it be the seal between the MC and booster or the seal that goes around the shaft that comes out of the booster? If its in the actual booster I can swallow having to pay $120 for a new booster, but if it's just a little gasket then I'd much rather just find another gasket.