• Team Vebo

BMW Engine Oil Leak

Updated: Oct 2, 2019



Leaky Engine?



Car owners in Malaysia may had experienced engine oil leaks throughout the lifetime of their ownership and this includes BMW too. This blog aims to share how the reader can detect oil leaks and see what happens inside the engine when a leak happens. So, sit back, relax and enjoy :)


Let's start with seeing how your car hints you that there's a leak.


When the engine oil level is low, here's how the BMW models from different generation warns the owner:


Low Engine Oil Message - F Series




Low Engine Oil Message - E Series



Low Engine Oil - No iDrive



So, you may wonder why do the driver not detect the leak on the floor where they park their car on? Where did the oil go? The answer is because most BMW comes with an engine cover at the bottom that will catch the leak before the oil reaches ground.



Bottom Cover Components


Some BMWs also come with an absorbent material that is capable of absorbing up to 2 liters of oil.


So the question now is that where does it leak from mostly? The photos below illustrates the possible engine oil leakage areas.



BMW Engine

The most common leak would be from the oil sump gasket.


Oil Sump Gasket Leak

The second most common leak would be attributed to the valve cover gasket.



Valve Cover Gasket Leak


Other components that may leak are illustrated below:


Oil Cooler Gasket Leak

Oil Filter Housing Gasket Leak

Main Pulley Seal Leak

Turbo Housing Leak

Cam Sensor Leak


Vanos Sensor Leak


Flywheel Oil Seal Leak


Vacuum Pump Leak

Spark Plug and Coil Seal Leak (Left Is Good, Right Is Bad)


Valvetronic Gasket Leak


Eccentric Shaft Sensor Leak

Next, let's explore why the leaks occurs.


This is because the gasket and o-rings within the engine are made mostly of rubber and they deteriorate over time due to long exposure of heat. This then allow engine oil to seep through the micro-cracks.


When?

Vebo would recommend tracking how often you would need to top-up 1 liter of engine oil as a gauge on how serious the leak is:




When there is a serious leak, take immediate action before the engine runs dry on engine oil, resulting in catastrophic engine failure. Go to your preferred mechanic to get it fixed.


For Intermittent and normal leak, the action to tackle it will be taken as per consideration below


Is the leak from the top of engine or bottom of the engine?


If the leak is detected from the top of the engine, especially from the valve cover gasket, it is best to tackle it when there is a chance. This is because gravity will pull the engine oil down, hitting a number of sensors on the way down. The engine oil will be able to go into very narrow areas within the engine bay.

With it ability to travel and carrying the hot temperature, most of the harness, socket and sensor will be affected when the engine oil leaks down. When left untended, the engine oil will eventually damage the other components.


As for the spark plug and coil compartment leak, it will lead to spark plug and coil failure which will then cause the engine to misfire, resulting in engine vibration.


How to fix the leak?

Upon identifying all impacted components, the engine needs to be dismantled to replace all relevant gaskets and o-rings. Simpler components such as the sensor o-ring would take about 30-60 mins to replace while more major job such as the valve cover gasket, flywheel oil seal and oil sump gasket will need around 4-6 hours each.


Conclusion

While engine oil leak is not uncommon, we hope that this article provides an insight of the different leak symptoms and for the driver to gauge how serious the leak is before deciding to repair the leak.


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