[@_salamander]

Hello guys, I’m new to blog. My 2006 E90 has a coolant leakage apparently. It has bluish marks from what I believe is dried coolant on the oil filter housing and alternator (see pics). I’m not sure where is it leaking from. I have checked the Mickey Mouse flange but that area has no bluish marks and it’s dry. Any clues on what could be and what’s the part number, please and thank you!

[mainbearing]

Upper radiator hose?

Coolant vent hose above the radiator and under the air intake snorkle?

Oil filter housing gasket? That does not look like typical OFHG leak, but maybe it is.

[lookalikehuuh]

I think if you start the coolant bleed procedure on your car you might be able to spot where the leak is coming from. Focus on the hoses at the top of the drivers side of the radiator and the radiator itself where the metal meets the plastic endcap.

Let us know if you don't know how to start the coolant bleed procedure. Essentially the procedure starts your electric water pump to help create water flow and a bit of pressure in the system which can help push coolant thru failing components.

Also, your oil filter housing gasket is leaking, you should get that fixed ASAP since it can cause pretty big issues for the car up to and including a serpentine belt that breaks and gets ingested into the engine and causes your engine to grenade due to it clogging the oil pickup tube.