On the various BMW 3 series forums I wasn’t able to find a good pictorial/instructional step by step post on how to change the spark plugs out on an N55 F30 335i. There isn’t much out there in terms of what needs to be done to access all of the spark plugs. Here you will find a detailed guide on removing the various covers, bolts, screws, etc in order to gain access to all of your plugs. I didn’t cover removing the plugs themselves in all that much detail as others have documented it in much more better ways. 🙂
I decided to document the “prep process” this past weekend, hopefully it helps some people out.
(Click on the pictures to get to the full 15MP resolution)
- 3/8″ & 1/2″ drive socket wrenches
- 3/8″ drive torque wrench
- 3/8″ drive, 12″ socket extension
- 3/8″ drive, 14mm deep well, thin wall, spark plug socket (I used this from ECS tuning)
- Here’s a well reviewed Prime eligible socket on Amazon
- 3/8″ drive, Universal joint (I splurged and bought the SK Tools Universal Joint)
- Craftsman, more affordable option that comes with all 3 sizes
- 10mm nut driver
- Torx T27 (any type)
- Blue LocTite
- External Torx T20
- I purchased this Lisle set on Amazon
- Compressed air
- Can or compressor, either works, used to blow debris out before pulling plugs
- 4 new Torx stretch bolts (BMW part number: 07147270121)
- The spark plugs can be ordered from BMW parts or purchased online. The model number must be Bosch ZR5TPP33S
- FYI: The shipping on these is very weird, I first got a shipment of 3, then a week later 2 more showed up, and then another week later the final plug showed up. Heads up.
- MAKE SURE YOU ORDER THE PLUGS WITH THE S in the part number. Very important.
Optional tools, made my life a little easier
- 3/8″ drive flex head socket wrench
- 3/8″ drive locking extension bar (I used these)
- Dental pick (Used to release locking extension bar while in the coil channel)
- 3/8″ drive, ratchet spinner (makes spinning the plugs in and out quicker)
- Remove the engine cover (pull up on the thing) and put it aside
- Remove the driver and passenger side cowls by using your 10mm nut driver on the 6 plastic “IKEA bolts” (90º degree turn to unlock)
- Remove the circled black power cover piece thing (careful, mine got lost in the engine bay) and then pull the power wire out of the channel holding it in
- Remove the rear engine rubber seal
- Pop out the 2 circular strut bolt covers around the center back area of the engine by reaching under them and popping them out with a finger or two (be careful as they will go flying out and into the engine bay!)
- Remove the two inverted Torx bolts located under these covers and discard them. (The discarding part is recommended, from what I’ve gathered on various forums these bolts are “stretch bolts” which are made to be torqued to a specific value + another 90º Here’s a link to the wiki article explaining it. I asked the dealer and they said they don’t replace the bolts, I checked ISTA and it specifically says to replace them, I checked the forums and there is a mixed bag of replaced and didn’t.)
- Follow the 2 strut bars and remove the inverted Torx bolts as done previously. One will be hidden under the shock boot. After you do this on both sides, pull the strut bars off to the side.
- Using your 10mm nut driver/socket, remove 6 bolts from another cover which is blocking access to the rear most plugs and the engine foam, 3 bolts on passenger side, 3 bolts on drivers side. (Note that this bolts have Loctite on them, do not forget to re-apply when done)
- Note that the cover you just removed is “pinned” with this plastic rivet. It’s possible you could get if off but I just put it to the side as it’s on the side of the engine where there are no spark plugs
- Unclip the two wire harnesses from circled mount and then using your T27 Torx, remove the highlighted screw from the top of the coil pack area on the rear of the engine. This will give you enough play to move the wires around when the coil pack comes out
- Now you finally have access to all 6 spark plugs.
- Torque specifications are:
- 41 ft/lbs + 90º on the replaced strut bolts
- 17 ft/lbs on the spark plugs
- BMW does not recommend any type of anti-seize but like everything, it’s a mixed bag on the forums, some say yes, some say no, I opt’ed NO
- Removing the coils may take a bit of force, first be sure to pull up on the marked corners of the coil (I used my index fingers), once that “door” flips open, remove the wire plug by pulling them away from the coil, use your finger or a round screwdriver through the loop of the flipped up door to break the suction and pull the coil out. Try not to turn the coil when pulling up.
- After removing the above coils and before removing the spark plugs, shoot a good blast of compressed air into the plug channel to remove and debris that may have snuck in there
- Be sure to use a universal joint of some sort when removing and installing the plugs. The plugs sit at an angle you wouldn’t expect (pointing down towards the coil chamber) they aren’t perfectly centered in the chamber and if you apply to much torque at the wrong angle you will snap the plugs and the insulator. The universal joint give the wrench the play needed to not snap a plug in half.
- A hand socket wrench makes spinning the plugs out and back in much faster, keep your extension bar on and spin away.
- Since this was my first time doing plugs I needed to invest a little money in tools. East Bay BMW quoted me $450 for the spark plug change.
- Tools = $80.00
- Universal Joint (I splurged on the SK tools version), extension bars, external Torx set
- Plugs = $84.00 from Amazon Bosch ZR5TPP33S
- 5 Strut bolts = $16.70
- Total: $180.70
- Tools = $80.00
- Be careful when popping off small covers, I lost that little plastic piece in step 3, and spent an extra hour or so getting the car up on the ramps, taking off the belly pan, and searching everywhere for it
- Bimmerpost forum post with a few pictures from the Bentley Manual and other tips: Here
- Link to the results of the spark plug change: Spark plug change results with borescope pictures and ISTA+ stats
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