I recently had the "opportunity" to remove my valve cover and didn't find any tutorials so I thought I'd post one. It's quite different from the N54 though likely similar to the N20 and N26. At any rate, it's not your grandfather's valve cover.
My PCV valve had failed at 80K Miles causing both the front and rear main crankshaft seals to howl like hyenas. More info here:
While I was at it, I took a look at the carbon buildup
. It's insanely difficult to unplug the ECU wires
but I got enough of them loose to pull the intake manifold off a little and take a peek. Didn't seem too bad to me for 80K so I just poked at them with a popsicle stick to get the chunks off and buttoned it back up. Pic below.
Special tools needed:
- 14mm and 17mm crows-foot wrenches to tighten fuel lines with a torque wrench. 23nm for the small ones and 30Nm for the big one. Keep the crows-foot 90 degrees from the wrench for accurate readings.
- 11mm crows-foot to loosen fuel rail without removing plastic clips. (Note: 11mm is not included with Harbor Freight set but is included with Tekton set)
- Standard short 22mm socket and long thin cheater bar if you want to rotate the crankshaft (turn it in the "tightening" direction) to clean your valves. Also some long thin brushes, and a small/thin turkey baster to suck out the goo. Vacuums or compressed air are not suitable for this.
- Compressed air for clearing all the dirt before it rains down onto your camshaft.
- Replacement covers include all the gaskets and bolts already installed, but if you're not replacing the cover you'll need at least the gasket set.
- Valvetronic connector gasket plate (11377502022) and 2 self-tapping screws (11367609963) are suggested by the repair manual, but not by me. They are perfectly reusable.
- The metal accordion PCV hose can simply remain attached to the valve cover if you are servicing something else, but if you need to remove it (e.g. to transfer it to a new cover) you will likely break the clips. You can drive just fine with few broken clips and order a replacement later (P/N is usually 11127584128). I transferred mine over without breakage and it's not easy but well worth the $30 savings. This is not a wear item so there's no reason to replace it unless broken.
- Six rubber caps to cover the exposed fuel injectors. Twelve if you don't remove the fuel rail. Threads are M12 x 1.5 so something around 7/16" diameter works well. Little Red Caps (condoms for your caulk) are perfect for this job but standard hardware store rubber bolt thread protectors are fine. Party balloons are another option. Tape is not suitable.
- Rag and rubber band to seal off the exposed lower intake pipe.
- Intake valve cleaner if you wish to clean your valves along the way. Carb cleaner could wick up into the valve guides and degrade the valve seals but "intake valve cleaner" is basically aerosol diesel fuel so it's safer.
- All 24 valve cover bolts: 8.5Nm / 6 ft-lbs
- Small fuel lines: 23Nm / 17 ft-lbs
- Large fuel line: 30Nm / 22 ft-lbs
- Fuel rail mounting bolts: 13Nm / 10 ft-lbs
- Strut bar center: 100Nm / 74 ft-lbs
- Strut bar to shock tower: 34Nm / 25 ft-lbs
- Intake manifold nuts and bolts: 15Nm / 11 ft-lbs
- Disconnect the battery as the fuel pump may run anytime the car is "awoken" from sleep. Also you will be doing a lot of tricky wrenching near the positive terminal. This is best done the night before so that there will be little or no fuel pressure in the lines. Otherwise the fuel pump will pressurize the system anytime a door is opened.
- Remove the passenger windshield wiper.
- Now that you know the windshield wiper is involved, reconsider your options.
- Slightly loosen one fitting on the fuel rail to relieve pressure and catch the spillage with a rag. Important: Don't remove any fuel lines or expose the fuel system until the very last step, otherwise you will surely get dirt in there and ruin some injectors. If you disconnect the battery the night before, hardly any fuel will drip out.
- Remove the cabin filter, cowl, and entire intake all the way to the lower front/right corner. There's only one screw on the lower intake pipe, no hidden tricks. You must cover the remaining pipe with a rag and rubber band or similar -- it leads directly to the turbo and things are going to get messy. The accordion pcv hose has single-use clips -- don't unclip it if you don't need to -- just unscrew the other end. If you intend to replace the valve cover you can try to unclip and reuse this hose by first twisting it to expose the 4th clip, then wedging thick washers into the 3 visible clips while you jam a screwdriver into the 4th. Good luck. It should be noted that the factory repair guide specifically warns that this hose cannot be removed without breakage. Note for reinstallation: it's much easier to reconnect the accordion hose while the lower intake pipe is still loose.
- Remove both strut bars and the center plastic panel on the firewall that they pierce thru (see here for details). There's a big plastic cover to unscrew for access to the strut bar centers. Once they're out, there are 3 screws on the firewall for the plastic middle panel.
- Remove the weatherstripping that runs across the entire front edge of the sub cowl and lift the top cowl section forward/upward, popping the clips as needed until the entire center section is completely free of the windshield. Start from the passenger side and work towards the middle. It need not come up around the driver's windshield wiper but it should come loose from the passenger wiper. You'll see that by lifting this panel, a large notch is exposed from the strut bar panel -- this is exposing the path that the valve cover will soon take.
- Remove the wires from the rear engine cover, then remove the cover by pulling up. Open the "ECU" box by sliding the two white locks and unhooking the 4 corners of the black clips by reaching under them. Lift the wire harnesses out of the box a little and strap them to the remaining windshield wiper to keep them out of the way.
- Remove all spark wiring. Unscrew all the brown ground wires (the entire harness needs to come out). The coil packs have obvious handles, flip them up a full 90 degrees (the cracking sounds are normal -- don't be shy) and the connectors will fall out on their own. Remove all 6 coil packs. #6 is in the way of the valve cover egress path and the other 5 block the crowsfoot access you'll need later to torque the fuel lines. To remove just pull hard, slide a rod thru the handle hole for grip if needed. Coil packs can be mixed up, it doesn't matter unless you are also trying to diagnose a spark-related misfire. Note for reassembly: The connectors need to be firmly pressed inward as far as possible before flipping the handle down to draw them in -- a design flaw makes it possible to get the handle to flip down, latch, and draw the connector in without actually drawing it in far enough to connect.
- Remove all injector wiring. Don't remove the T-shaped metal brackets securing the injectors, just disconnect the wires. The injectors each have a small 2-wire connector identical to the one on the heater of that hard-accordion PCV hose you removed in step 5 but are much harder to get to. They all face the same way. Use two small flat screwdrivers: one to disengage the lock on the rear right of each connector while the second pries up on the edge of the connector housing (see pic below). The entire harness lifts out of the way after some screws and clips. Don't worry about numbering, the harness makes all the wiring foolproof. And don't worry about those two big plugs in the back that look identical -- they aren't. The big round connector in the center is for valvetronic and the gasket plate needs to be removed from the base. For some reason they suggest replacing those 2 screws and the gaskets but I don't see any reason to. Note for reassembly: The wire harness only has the rear screw at this point because the front screw is shared with the intake track and was removed in step 5.
- Clean everything you see. Lots of compressed air and whatever else you have. Pay close attention to the area around the windshield wiper, all 4 gasket perimeters, and all fuel line nuts.
- Remove all vacuum and PCV hoses. The little hard-line vacuum hose that drapes across the middle of the engine has a weird ring that you're supposed to squeeze to release -- squeeze it really hard. The pair of conventional rubber vacuum hoses connected directly to the valve cover simply pull right off... in theory. The slots are there so that you can use a small screwdriver to lever each hose off the nipple. There is no barb and no trick to this, it's just really stuck. You might want to remove the short hose entirely so that it doesn't get knocked off and lost.
- If you're going to remove the intake manifold to examine/clean your valves, this is the time to do it. The loose wiring harness means that fewer ECU plugs need to be disconnected, and with the manifold off, the fuel rail in the following steps is simple to remove. It's a tough task to disconnect the ECU plugs so if some can remain connected it'll save you some struggle. You can fit a standard short 22mm socket wrench between the engine and fan to turn the crankshaft but be careful not to hit the little expansion tank hose at the top left corner of the radiator -- the barb is very brittle.
- Loosen all the valve cover bolts. Use some combination of size adapters and u-joints to make extensions just the right length for the rear bolts. The right rear bolt is a doozie. Best to have a friend hold the socket/u-joint while you work the wrench. Try not to drop the socket, it's very difficult to find stuff in that part of the belly pan. This bolt alone could be a 30 minute job depending on how many times you drop the wrench.
- Make sure all the valve cover bolts are completely loose. It's hard to tell because they don't come out and you will surely miss a few even after double-checking.
- Save the fuel lines for last. One speck of dirt might cost you a new injector so be careful. You could leave the rail in place and only remove the 6 lines but the valve cover needs to go that direction in order to reach the strut bar opening so I found that removing the entire rail is preferable. The two plastic clips on the fuel rail will be broken if you try to remove them and replacements are not affordable. You can get a slim 11mm crowfoot in behind them or remove the intake manifold to reach them with a regular wrench. If you break the clips make damn sure you find the broken plastic bits before opening the valve cover. Luckily they still work fine even after being broken.
- Fuel injectors need to be capped with some nice-fitting 7/16" (12mm) caps of some sort. Tape won't stick and the fuel will make a gooey mess of the tape adhesive. There will be lots of chaos and dirt ahead and one speck of dirt will destroy the injectors so you need to have a solid plan for this. The fuel rail supply nut also needs to be covered before you start banging your dirty valve cover into it, which you will. You can put some tape over the big rail nut but the injectors need proper caps -- you'll be banging stuff into them, especially #6.
- The valve cover lifts up easily but it's pretty difficult to find a path to get it out. Have a friend bend the cowl/firewall area while you zig and zag to wiggle the cover out. Now you will see why the windshield wiper needed to be removed and the injectors needed to be protected. Dirt will rain from the bending cowl onto the #6 injector and you won't even be able to keep track of the trauma faced by the other injectors. Don't force anything -- find a way to get it off gently and then remember how you did it so that you can reinstall in the same manner.
- Reassembly in reverse, but try not to cut the valve cover gasket on the razor sharp edges of the camshaft rear bracket. Remember, the E92 was (obviously) never intended to have an N55 so it's only by some freak chance that this procedure is even possible at all. Torque the valve cover bolts to 8.5 N-m in a crazy cylinder head-like pattern starting with the F/R corner, R/L corner, centers, then the remainder. Fuel lines should be lubricated with "transmission oil" and torqued to 23Nm and 30Nm respectively. Thoroughly inspect them for debris prior to assembly and of course, put the fuel lines back on ASAP to lessen the chance of contamination. If installing a new valve cover don't forget to transfer all the little screw-in balls and stuff over one by one so that you get everything in the right hole. It's not entirely intuitive so do this soon, before you get all the wires and stuff in the way.