hello, the Oring behind the vacuum pump on my 04' 545 was leaking. I got the Oring from my dealer, the part # 116675509080.
The vacuum hose at the top and front has to be removed and the brackets holding the power steering and coolant lines have to moved sway to make enough room. The Flat screwdriver like flap slides into a slot and get rotated by the camshaft while engine is running. no leaks now. pics attached.
It takes about 30-45 mins at a leisurely pace.
NOTE: the 3 bolts that attach the vacuum pump to the head are a special TORX type # 6 size. you can check that bolt in the last pic. make sure you have this socket before attempting this. i also got an extra bolt in case i stripped it.

 

Nice DIY! Congrats on the fix and thanks for posting part #'s. I guess our 545's are notorious for this type of repair because it appears I may need to be changing mine (oring also) soon. Thanks

 

are you positive the o-ring on the rear of the pump was leaking?
usually the o-ring under the front cover of the pump losses its shape, and starts leaking.

 

How did you know that this was leaking? Ie what are the symptoms?
Thanks.

 

you'll see a dirt/oil film under the pump. and if it leaks enough, you'll have oil dripping on the belly pan.

 

+1. Thanks .

 

Talked to my dealership wondering if same problem happens with the 530. Anyways, they say this pump for the 545 costs $460 retail from the dealership. Not cheap.

 

where does the vacuum line that plugs into the small connection on the front of the pump lead to? I had to cut the end off that hose and reattach it this morning as it was cracked. just wondering if that was causing my fluctuating idle when the car is cold.

 

Anyone? Im replacing my pump and I noticed this line wasn't even connected...