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Z4-Specific N52 Valve Cover gaskets and seals

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Z4Mariner
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Z4-Specific N52 Valve Cover gaskets and seals

Post by Z4Mariner » Fri Feb 03, 2023 2:04 am

N52 Valve Cover – VC gasket, ESS sensor, ESS seal, and Valvetronic motor seal
(note: N52 = magnesium VC, N52KP and N51 = plastic VC)

My 2006 Z4 3.0Si Coupe has 89K miles and is now over sixteen years old. I’m getting to know the car, learning which items are in need of work, and addressing them to keep the car driving and looking close-to-new for the next decade or so. One of those items was checking under the magnesium Valve Cover (VC) and renewing the VC gasket, the ESS seal, and the Valvetronic motor seal. The ESS seal was starting to seep oil, the VC gasket could have done a few more miles. An additional item was replacing the ESS sensor itself, not yet gone bad on my car, but a ‘while I was in there’ thing.

I decided to document this process for E85 and E86 Z4’s with the N52 engine - different from the N51 and N52KP engines, which have plastic VC’s and steel VC screws. The basics of this job on N52 engines can be found in part in other references (Bentley manual for E90, E91, E92 cars, as well as on the web). It’s harder to find Z4-specific detail. In the US, only 2006 LCI cars have the N52 with the magnesium VC.

First off, a parts list:

1) VC gasket set (BMW 11127581215, Elring 537890)
2) VC aluminum 7mm bolt set (BMW 11120409288, Mahle GS33637)
3) ESS seal (BMW 11127528242, Elring ELR-523000)
4) Valvetronic Motor Seal (BMW 11377516302, AJUSA 01098800)
5) ESS sensor (BMW 11377524879, VDO/Continental S119565001Z)
6) Spark plug wiring harness screws (BMW 13627530413) – Aluminum 6mm E-Torx

The ESS Sensor might not be an absolute necessity, but if you don’t change it, and it goes bad, you will need to re-do the entire VC removal, use new gasket & bolts, etc. The VDO Continental ESS sensor is OEM, and saves half of the BMW price. The pair of wiring harness screws (item #6) are mounting / grounding screws. They are not torqued much, unlike the VC screws. Because I had no new ones, I have reused them until I can replace them.

After writing this up I came across this video from George Austers: https://www.youtube.com/watch?v=5wi-EKbSYJ4
It covers much of what I have written up, but not in a Z4. His focus was replacing the ESS, but it’s still a magnesium VC on an N52 engine . . . He has a separate VC gasket video as well, which I have not linked.

This job is less difficult than for a 1-Series or 3-Series chassis, since Z4’s don’t have the cowl air box overhanging the VC. I have done the plastic VC on a 128i which I once owned.

Step 1: Remove the silver VC beauty cover – pulling straight up should pop it off of a set of four aluminum pins permanently mounted onto the magnesium VC. If you undo the five Torx fasteners instead, you’ll see that they connect the plastic beauty cover to an aluminum frame that holds the rubber grommets which attach to those VC pins.

Step 2: Remove connectors for oil pressure sensor, oil temperature sensor, and both VANOS solenoids to free up the fuel injection harness and the ignition harness. The only connectors you might mix up will be the two VANOS connectors, so take a photo, label them, or look really carefully and use good memory.

Step 3: CAREFULLY release the clips which hold the fuel injection wiring harness onto the injectors. You don’t want to lose these (I have seen statements that they aren’t sold separately – I don’t want to fact check that statement). Best tool for this is probably a 90-degree pick with a somewhat blunt end, at least for me. You may need to cover your front fender and lean over it to do this. Once clips are released, lift the harness off the injectors and carefully restore the clips in their grooves so they are ready to reinstall.

Step 4: Cut the zip ties at the back of the engine which hold the spark plug wiring harness and O2 sensor cables to the cylinder head (replace them on install). Disconnect the O2 sensor connectors to allow slack in the cables. There is a zip tie for the O2 cables on the right side of the engine which I cut also.

Step 5: Now that the cables can be moved away from the rear of the engine, use a pick to help you disconnect the CCV (or PCV, or CVV) hose from the rear of the VC. The plastic will be brittle, and squeezing the connector may not be enough to get it free without breaking it. This leaves you ready to remove the right-side cross brace (cowl to strut tower), the ignition harness, the spark plug coils, and the Valvetronic motor.

Step 6: Loosen the 16mm M8 nuts for the right side cross brace (cowl to strut tower). Remove only the strut tower nut, and swing the brace over the engine intake. Because you clipped the zip ties and unplugged the sensors you will be able to create some slack and pull the rear portion of the ignition harness and O2 sensor cables up over the engine heat shield to give good access to the VC screws at the back of the engine without removing the heat shield.

Step 7: Remove the harness connectors from the coils, and remove the coils. You will not be able to access the Valvetronic motor screws until you have removed the coils from cylinders 3 and 4. If the plugs are original, the coil boots may be glued to the plug insulators – I needed a bit of silicone spray lube down the cylinder 4 hole to help break that coil pack loose. Unscrew the two Aluminum E-Torx M6 screws which retain (and ground) the ignition wiring harness to the VC.

Step 8: Remove the Valvetronic motor by using a 4mm Allen (hex) key to screw the Valvetronic motor shaft clockwise until you feel resistance. Once it is screwed in, you are ready to remove the three E-Torx screws (E8, steel) holding the motor. These are steel, and can be reused – note that they don’t screw into the VC casting at all, but instead they screw into the aluminum cylinder head or the aluminum insert below the motor. Undo the pinch screw under the motor first, then the two visible screws in the motor ears. After removing all three, rotate the motor shaft counterclockwise to ‘unscrew’ it from the eccentric shaft.

Step 9: Remove the 22 Aluminum (M7) VC screws, working outside-to-inside. My replacement set was from Mahle®. Three have 10mm Hex heads and go in the valley between the cams, while the other 19 are E-Torx (E10). Once they’re all out, remove the VC. My gaskets stuck to the VC.

Step 10: Clean the cylinder head mating surface well to get ready for the new VC gaskets. This is the point at which I installed the new Eccentric Shaft Sensor (ESS). The ESS holes are threaded, so the screws are ‘captive’, BUT take care to let each corner of the ESS move away from the casting as bolts unscrew to be sure they don’t thread into the holes in the ESS an possibly become loose. The bottom 10mm head screw requires a 10mm socket (¼” drive is good) that fits through an access hole in the timing chain guide (10Nm).

Install – Step 1: My VC gasket seemed original to the car (manufacture date before that of the car), and had a sealant or anticorrosion treatment between it and the gasket. I sanded the sealing surface of the VC lightly with 600 grit Wet-or-Dry sandpaper glued onto a flat aluminum plate, but I tried not to remove all of this “coating”. I removed the old Valvetronic motor gasket and the old ESS seal and cleaned both sealing areas. After giving the VC a rinse with brake cleaner, I installed the ESS seal (the Valvetronic seal goes on with the motor). I placed the gaskets on the cylinder head surface, located by dowels. With a very thin layer of Permatx® Ultra Grey sealant on VC sealing surfaces only, I dropped the VC into place. I used nothing on the cylinder head side of the gasket.

Install - Step 2: Work inside-to-outside installing the Aluminum VC bolts – tighten the inner three M7 bolts with 10mm heads first, then the rest in a ‘spiral pattern’ starting at the middle. I started all the bolts carefully by hand with a socket and no wrench handle. Then I tightened all the bolts in the pattern described to 63 in-lb. (7 Nm). Let sit for 30 min, then tightened again in same pattern by an additional 90 degrees, marking each one as I went.

Install - Step 3: Now for Valvetronic motor reinstallation – this has to be done before the ignition coils go back in. Use either no sealant or the thinnest-of-thin smear of sealant on the Valvetronic motor gasket. Fit gasket over the cleaned-up motor and insert the motor into the VC, using your 4mm Allen key to screw the motor shaft clockwise into its eccentric shaft gear until resistance is felt. Now you can start the M6 E-Torx (E8) screws through the motor ears into their holes. Tighten to 10 Nm (7 lb-ft). Then add the third M6 screw under the motor and tighten it to 10 Nm (7lb-ft). This leaves the Valvetronic motor in ‘service position’. The car will eventually relearn the Valvetronic limits, but you can short cut this by running the limit learn using software tools.

Install - Step 4: I took the opportunity to change my spark plugs at this time as well. The old plugs were consistent light tan/grey color, though the ground electrodes had erosion next to the precious metal inserts. These were pretty likely the original plugs (89K mi). Plugs were installed and torqued; coil packs were installed with dielectric grease to ease next removal.

Install – Step 5: While the remainder of the installation is the reverse of removal, there are some things to remember: Replace all zip ties removed, confirm fuel injector connectors all click home, confirm all coil pack connectors are fully engaged, check that the remaining electrical connectors are completely seated, and refit the right-hand cross stay with its 16mm (M8) nuts torqued to 35 Nm.

Hope someone finds this useful and takes encouragement to do some wrenching on their Zed.

Mark


Attachments
N52 w Beauty Cover removed.jpg
N52 w Beauty Cover removed.jpg (53.38 KiB) Viewed 487 times
ESS seal starting to seep oil.jpg
ESS seal starting to seep oil.jpg (122.82 KiB) Viewed 487 times
Fuel Injector clips - one still 'released'.jpg
Fuel Injector clips - one still 'released'.jpg (104.18 KiB) Viewed 487 times
Injector harness removed & out of way.jpg
Injector harness removed & out of way.jpg (158.63 KiB) Viewed 487 times
Coil pack blocking Valvetronic motor.jpg
Coil pack blocking Valvetronic motor.jpg (139.76 KiB) Viewed 487 times
Ignition harness over Heat Shield & Cross Stay moved.jpg
Ignition harness over Heat Shield & Cross Stay moved.jpg (113.7 KiB) Viewed 487 times
VC before cleaning - no sludge or varnish.jpg
VC before cleaning - no sludge or varnish.jpg (110.86 KiB) Viewed 487 times
Z4Mariner
Minnesota, USA

2006 Z4 Coupe 3.0Si, Montego Blue, MT

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Z4-Specific N52 Valve Cover gaskets and seals

Post by bigwinn » Sat Mar 16, 2024 5:48 pm

Great write up Mark thank you
If the forum helped you, why not help the forum back. Thats the Z4 way! :thumbsup:

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