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      09-10-2021, 09:23 PM   #1

Drives: 2009 BMW M3
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Question Oil leak by alternator HELP

Hi All,

So I picked up a 09 car and had the road bearings, oil pan gasket and valve cover gaskets immediately replaced. I still have a oil leak coming from somewhere right by the alternator. I have had the valve cover gaskets re-checked to make sure those were not the sources of the leak. The leak is significant enough that if I drive the car 200 miles or so, the oil gauge on iDrive will read 1/4 lower from max. Has anyone else experienced a similar issue and if so whet was the source of the leak?
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      09-12-2021, 10:42 AM   #2
drrust's Avatar

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I would suggest removing the air box for a good look at the valve cover on that side of the motor. Take a look at the oil separator too, but that is in the middle of the engine.

Have you confirmed there is oil leaking on that side of the motor? Also is the 200 miles all highway? Sometimes after straight highway driving the oil sensor can read low, but if you let the car sit, the oil level rises.
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      09-12-2021, 06:33 PM   #3
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The oil sensor doesn't actual show the total oil you probably are only down a 1/4 of a liter. If you are down a full liter you will get a yellow warning...much more than liter, a red warning will appear.

The M3 S65 V8 burns oil, no matter what you do. Change your oil every 5k-7.5k...regardless of the 15k recommended interval.

If there is oil on the ground, then I am guessing that the prior servicing wasn't done 100% correctly. The BMW M3 is so complex, you can't have it serviced at just any shop.

There is a large oil filter housing on the passenger side of the engine bay that could leak on very high mileage M3s. Alternator is on the driver's side.

The oil cooler behind the front facia could also have a small puncture, caused by road debris. I already went through two oil coolers after 190k miles.

The other option is a power steering fluid leak.

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