The Dangers Of Lifting Engine Covers

Michael Karesh
by Michael Karesh

BMW hasn’t offered a four-cylinder engine in the U.S. for quite some time, so I was eager to check out their new 2.0-liter twin-scrolled turbo. A Z4 so equipped arrived in my driveway today.

Not to give too much away prior to the full review, the new 240-horsepower engine works very well when paired with a six-speed manual in the 3,263-pound Z4.

Then I broke it.

As is often the case in the post-Lexus era, an engine cover hides the goodies. Knowing that some of you would like to see what’s going on under the cover, to serve the common curiosity I pulled it off. The cover readily pops off the left side of the engine, but some vacuum lines restrain it on the right side. Belatedly I discover that BMW hasn’t merely fitted a cover—they’ve attached a vacuum accumulator to its underside. Why? Beats me. I’m not going to detach any lines, so I just hold the cover up to the side while grabbing a quick photo.

Yeah, BMW’s new four isn’t a pretty sight. This mill badly needs its cover.

Replacing the engine cover proves a bit difficult. My first attempt misses the attachment points. Popping it back off for another attempt, I hear a “whoosh” as a vacuum line pops off of its fitting. My second attempt hits the attachment points. I then find the loose vacuum line, find a fitting that’s missing a line, and reattach the line.

Start the car up, drive a few blocks, and the yellow CEL lights up. Boost is either severely restricted or gone. (Though, surprisingly, the engine still doesn’t feel terribly underpowered. Perhaps this is what the lesser-engined Euro-market BMWs feel like?) Back in my driveway, I do the smart thing this time, and reference a photo I took before removing the cover. Seems two lines had come loose, and I’d only reattached one of them, and to the other’s fitting.

I fix this, but the CEL won’t go out even after I stop and restart the car a few times. I resign myself to a trip to the dealer to have the light reset. The next morning the light is still there when I start the car to head to the dealer. I drop by the kids’ school first to drop off some things for one of them. I then get back in the car, restart it, and—with the dealer next—no light and full power. Perhaps the car needs to be driven a certain number of miles before the computer concludes that the earlier problem is gone?

Needless to say, I’ll be more careful next time I pop off an engine cover—they’re not just for covering up the engine anymore!

Michael Karesh
Michael Karesh

Michael Karesh lives in West Bloomfield, Michigan, with his wife and three children. In 2003 he received a Ph.D. from the University of Chicago. While in Chicago he worked at the National Opinion Research Center, a leader in the field of survey research. For his doctoral thesis, he spent a year-and-a-half inside an automaker studying how and how well it understood consumers when developing new products. While pursuing the degree he taught consumer behavior and product development at Oakland University. Since 1999, he has contributed auto reviews to Epinions, where he is currently one of two people in charge of the autos section. Since earning the degree he has continued to care for his children (school, gymnastics, tae-kwan-do...) and write reviews for Epinions and, more recently, The Truth About Cars while developing TrueDelta, a vehicle reliability and price comparison site.

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  • Wmba Wmba on Nov 11, 2011

    "Vacuum reservoir for the wastegate valve permanently connected to the engine cover." From BMW Technical Training for N20 engine. Having read that very long article, I'd be afraid to turn the engine on! Quite the technical exercise. At least BMW have gone to great lengths to properly vent the engine and to filter oil out of the PCV gas stream, so coked up intake valves aren't likely. VW/Audi direct injected engines are not so lucky, and use an older type DI system anyway.

  • Excepticus Excepticus on Nov 28, 2020

    Hey. I wanted to ask something. When you take off these engine covers. there are many wiress and other kinds of cables to be seen. I just wanted to ask why they make them this way. when you look at older cars for example lets just take a miata or sth, you didnt have all these wires on top of the block and under the cover. Why do these new cars have so many complicated wires? please help. I am really frustrated because i havent got an answer to this.

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