This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.
One of the more common oil leaks on BMW engines is the large, long valve cover gasket.In general, it's pretty easy to remove and replace this gasket. This article goes over in detail the procedure to replace the valve cover gasket. Begin by prepping the car. The only thing that you really need to do is to make sure that the car is cold. If you try to remove or install spark plugs in a hot car, then you may encounter problems with the spark plugs gumming up or damaging the relatively delicate threads in the aluminum cylinder head. Just make sure that the car is cold, or at the bare minimum, only slightly warm to the touch.
Let's talk about the six cylinder cars first. The first step is to remove the top plastic covers from the engine. These serve no mechanical purpose - they are there only for decoration and to prevent dust and debris from getting into the recesses of the engine. On the six cylinder cars, there are two covers, a long thin one on the top of the car, and a wider one towards the left. Speaking of left, for the purpose of this particular tech article, I will refer to the left side of the engine as being on the left as you are standing in front of the car looking at the engine. The right side would, of course, be opposite to that. For reference, the windshield washer bottle would then be on the left, and the air filter would be on the right.
On the two plastic covers, there will be two small, snap-in plugs on the top. Carefully remove these plugs (don't drop them into the engine) with a small screwdriver, prying them up as you grab them (Figure 1). Underneath you will find a nut that holds the cover onto the top of the engine (Figure 2). Remove the four nuts on these two covers, and they should both simply slide up out of the way. Figure 3 shows the engine with the center cover removed.
Underneath the left cover, you will see the six spark plug coils that sit on top of each of the plugs (Figure 4). You need to remove each of these carefully, in order to gain access to the plugs. Using a screwdriver, release each connector from each coil. There is a metal retaining ring on the rear of each one that fastens it to the coil (Figure 5). Once you lift up on the retaining clip, then the connector should simply slide out of the coil. Carefully remove all of the connectors from each coil (Figure 6), taking care not to bend the wire harness too much. These wires are stiff, and generally don't take well to being bent in multiple directions. Just be gentle with them.
To assist with your maneuvering of the wires, detach the center clip that holds the wires that come from the center channel. This clip is shown in Figure 7. Gently place the wires off to the side and out of the way, without bending them terribly.
With the wires detached and placed slightly out of the way, you can now remove each of the six coils. Each coil is fastened to the valve cover using two screws. On two of the coils, there are two small ground straps that connect the coil to the stud on the cylinder head. Take note of these ground straps - they must be installed properly when you are finished, otherwise your car may encounter problems. These two ground straps are shown marked by the greens arrow in Figure 8 and Figure 9 (coil already removed in this photo).
Remove each of the two nuts that hold each coil to the valve cover. At this point, the coil should be able to be easily pulled right off of the engine (Figure 10). The coil has a small coil pack on one end, and a spring-loaded spark plug connector on the opposite end. Simply remove the coil/plug assembly and place it off to the side. All of the coils are the same, so it doesn't matter which cylinder bank it came off of - unless you are specifically trying to troubleshoot a bad coil fault code that was displayed by the main computer.
With the coils removed, you can now remove the top plastic cover on the wire harness box that straddles the intake manifold and the valve cover (Figure 11). The lid on this box simply snaps off. With it removed, you can then reach in so that you can carefully pull the wire harnesses out of the way (Figure 12). At this point, you can start removing the nuts that hold on the valve cover. Take careful note of which ones have ground straps attached (Figure 13), and make sure that you record where they are located so that you can put them back into their proper place when you're reassembling the valve cover.
Some of the nuts may be difficult to reach, in particular the one located all the way at the rear of the engine compartment underneath the windshield wipers (Figure 14). A small ratchet comes in handy here. When you have removed all of the nuts (there should be 15 of them), take a rubber mallet and tap the side of the valve cover to loosen it off of its gasket (Figure 15). You should then be able to remove the valve cover.
Inspect the valve cover when it comes off. In particular, be careful with the baffle and seal on the inside (Figure 16). This seal does not appear to be available as a separate part (it comes with the valve cover). The good news is that it doesn't really do much - it just seals an air baffle to the valve cover. Also, when you remove the valve cover, make sure that you don't loose any of the rubber grommets (Figure 17), or flat washers that hold them in.
If you take your valve cover into your machine shop to be sand blasted, make sure that you assemble all of the bits and pieces back together in their proper order. Especially important are the rubber studs that hold on the top plastic covers (Figure 18), as well as the baffle on the inside of the cover (Figure 16).
Prep both the surface of the cylinder head and the valve cover for the new seal by carefully cleaning all remnants of the old seal off of all of the mating surfaces. Be careful not to scratch any surfaces, and also be careful not to drop bits of pieces of the gasket into your engine.
The BMW factory manuals recommend adding some sealant to some leak-prone sections of the cylinder head. I chose to use Permatex High-Temp RTV, and it worked very well for sealing these areas. Specifically, the factory recommends adding sealant at the interface where the VANOS unit or front mounting timing chain cover meet (Figure 19 and Figure 20). They also recommend a small bit of sealant at the rear of the cover (Figure 21).
With the sealant attached, simply place the new gasket on the cylinder head (Figure 22). Place the two inner gaskets on the spark plugs holes in center of the head (Figure 23). These are the gaskets that leak oil into the spark plug holes (see the Pelican Parts Technical Article on Replacing Your Spark Plugs). Finally, bolt down the cover, and reattach all off the nuts on the cover, making sure that you replace the rubber washers/bumpers under each one. Using a torque wrench, tighten the nuts down to 89 in-lb (10 Nm). Figure 24 shows the finished product.
If you haven't replaced your spark plugs, now is a good time to do it. See the spark plug replacement article for more details. Reinstall the coils, reattach the wire harness, and replace the top plastic covers.
Well, there you have it - it'sreally not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.