How to locate an oil leak??

**jillian.11** · 08-14-2018, 09:08 PM

I recently purchased an e90 328i. Upon purchasing the car I knew it was leaking oil due to the very low oil level. The valve cover was leaking in December and the previous owner claims to have had it "fixed". He had the job done from a shady independent shop so I'm not sure exactly what they might of done. The car just hit 74,000 miles and already is having issues. I'm not sure where it's leaking from and was wondering if anyone knew how to locate where it is leaking.

A few questions:

-Is this common for a e90 to be leaking oil around 70k miles?
-How can I locate the leak?
-Also, how hard is it to DIY it? I don't have a lot of tools for working on cars.

**jclausen** · 08-14-2018, 10:46 PM

Valve cover gasket, oil filter housing and engine oil pan gasket the most common leaks they happen at all sorts of different mileages. Best way to find them is looke at the Valve cover gasket and the oil filter housing are both easy to see.
For the oil,pan gasket it would be nice to rack the car. The oil filter housing gasket if it's leaking a lot will drip down to the oil pan gasket area, making it look like the oil pan is leaking.

**marcva** · 08-15-2018, 06:38 AM

It might be a good idea to spray around the suspect areas with simple green and gently rinse them when a hose to get the extra oil off. It will be easier to spot leaks, though the three areas above are common for these motors.

Valve cover gasket is pretty easy... It's just a lot of fasteners to get off. Use the factory gasket. Oil filter housing isn't too bad a job. Just don't over torque the bolts when you put it back in. They're very low torque. Pan gasket is the biggest job, but hopefully most of your issues are the other two. Search for DIYs online. There is a good one for filter housing available...I think Doug's domain. Though it was an E36, a lot of the mechanical are very similar through the modern motors. The big difference will be the extra turbo plumbing.

**TostitoBandito** · 08-16-2018, 02:02 AM

As has been said, the most common leak points tend to be all the seals/gaskets, so various points on the oil filter housing, valve cover gasket, oil pan gasket, and sometimes the dipstick on certain cars.

It should be fairly easy to eliminate the oil filter housing by giving it and the area around/below it a good inspection. If it's the valve cover or oil pan, the oil all tends to accumulate in the same place on the very bottom of the pan as it drips down. If it's the valve cover you should be able to look up and see signs of fresh oil along the path of least resistance from the lowest edge of the valve cover down the side of the motor to the pan. If there's nothing coming from the valve cover and still a bunch of oil accumulating on the pan, it's probably the pan. If you're having trouble locating the leak, you could always do an oil change with some of the liqui-moly oil that's UV green for easy detection under a UV light.

And yeah, cleaning as much of the residual oil/dirt from any easy-to-reach places will make it that much easier to isolate any leaks.

**bmwdirtracer** · 08-16-2018, 06:18 AM

Look for the wet spot that's highest up and furthest forward.

If you do the OFHG, you should buy a universal-jointed E-10 socket, 1/4" drive, and an E10 Gearwrench ratcheting box-end wrench. These will save you from having to remove the manifold, or having to unbolt the front center coolant hose fitting, which will self-destruct if you mess with it.