Oil leak at valve cover

Tiny
DIVIDES
  • MEMBER
  • 2012 BMW 328
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 130,000 MILES
I bought this car 8 months ago, had an oil leak that leaked onto the exhaust. Doing so many BMWs covers in my lifetime I removed the cover and replaced the gasket, lasted 5 months, but I sold it before the 5 months to a friend. 2 months after driving it he said there were similar symptoms, didn't make sense, so I replaced the whole cover with gasket with a good brand, not the junk ones. They drove it for a month and now the same thing, a very obvious leak on top of the exhaust, I don't understand, there is nothing else. I also replaced the vacuum pump seal, which is in the back, twice.
Monday, May 16th, 2022 AT 6:05 PM

2 Replies

Tiny
BORIS K
  • MECHANIC
  • 836 POSTS
Hello,

It is worthwhile checking if the previous valve cover leaks did not cause the exhaust/turbo heat shield to absorb a good amount of oil. This is then released as the heatshield heats up.
An easy test would be to remove the heat shield, clean it, and then hold it over a source of high heat, such as a gas stove. Hold it there for a while to become really hot and then check if any oil oozes out

Another test would be to add some leak dye into the engine oil, clean the oil leaks and surrounding area. Drive the vehicle until oil is found to be leaking again and then check using a UV light if there is any dye in the oil, indicating a fresh leak from the engine.

See picture below, this kit is available from Amazon and other retailers

Another reason for engine oil leaks could be a malfunctioning PCV valve. This should have been replaced together with the new valve cover.

Hope this helps.

Cheers, Boris
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Tuesday, May 17th, 2022 AT 6:58 AM
Tiny
DIVIDES
  • MEMBER
  • 910 POSTS
Yes, the PCV on these is built into the valve cover and I replaced the o ring on the hose behind the cover twice. I don't think it's the heat shield as when I saw the oil leaking, it was dripping down onto the exhaust. The smoke from the heatshield was there until it all evaporated and I drive the car enough for it to disappear and watched it for hours to make sure nothing else leaked on the exhaust, just strange.
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Tuesday, May 17th, 2022 AT 7:02 AM

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