The Dangers Of Lifting Engine Covers

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!