[VPATEL11]

11

[cpie168]

Google BMWizard and make an appointment for him to take a look. That’s the best advice I can give you.

[Nick.B]

Is there any white milky liquid visible under the oil filler cap? That would indicate water in the oil.

You made no mention of a low coolant warning. Is the coolant low? If it's not low, it's not leaking anywhere. It should run just fine with the coolant low enough for it to cause a warning, but not overheat. An N55 does (had a leaky coolant cap) an N52 does, (had leaking o-rings or hoses) and an N62 does (valley pan tube gasket).

If the coolant level is fine and it's overheating, it's almost certainly a waterpump or thermostat issue. Are there any fault codes in the DME? There's at least one for the waterpump, re: communications failure.

[kenmar]

Instead of guessing, perform the usual engine diagnostic tests:
- leakdown test
- compression test

It is possible that a slow, tiny leak may not show up in those tests, so I would also perform engine oil analysis to check for coolant mixing into your oil (Blackstone Labs).

[Wolf 335]

Sounds like a water pump that is on its way out.