[DirtyHal]

Howdy,

I'm doing some maintenance this weekend, replacing my oil filter housing gasket, valve cover gasket, filters and belt. Just started tearing into my car and I saw this part and it looks like it's leaking. I'm kind of new to BMW so I'm not sure what it is. Could one of you identify this?

Thanks!

[Speed_Addict]

Turbo system diverter valve. When you let off the throttle under boost it diverts the charged / pressurized air going to the intake / throttle body back into the unpressurized side of the turbo system. If the diverter valve was not there, there would be no place for the charged / pressurized air to go when the throttle was suddenly closed which would possibly pop the turbo system's plumbing apart and cause back pressure on the turbo's compressor blades damaging them over time.

The car's Positive Crankcase Ventilation system which vents combustion gasses that slip by the piston rings and oil vapor gets is positive vacuum draw by being vented into the turbo system and thus some of that oil vapor condenses in the turbo system's plumbing and may seep at some connection points - in this case at your diverter valve. Yours may be a bit oily but probably fairly normal. I keep my engine bay spotless and I am low miles (under 44,000 on an '08) so I cannot really say what mine would look like if I never detailed the engine bay...

[DirtyHal]

Thanks for the response! I ended up cleaning it off and I'll try and check on it every once in awhile.

Overall I got both my gaskets in, and my new belt but broke the breather line on the back of the engine and the Pressure hose that connects to the brake booster line because my clumsy fingers don't like old plastic I'll have those tomorrow and I'll be able to put it all back together.

[BudgetBimmer]

Good info. Sounds like a Blow off Valve to me. Are they one and the same?

[GATORB8]

Originally Posted by BudgetBimmer

Good info. Sounds like a Blow off Valve to me. Are they one and the same?

Basically, the diverter just pipes the "blow off" back into the intake tract before the turbos.