This message is marked as Important.

Subject: Changing spark plug wires Author: davidc (moderator) : member since December, 2003 : 10347 posts Posted on: 2004-06-10 13:21:20

I've not changed the rotor cap on the e23 yet (the previous owner did that one for me), but I've done it on other cars. You have to remove all the wires, number and label them first, then the rotor cap should either pop off with spring clips or have a couple of screws.

Changing the spark plug wires is easy. Get the Beru brand set as it includes the rubber boot that protects the coil from water splashes. The Bosch set lacks that part.


First, remove the two nuts securing the black air filter box below the edge of the washer fluid reservoir. 10mm, as I recall.


Then use an 8mm wrench to loosen the hose clamp around the rubber boot that connects to the air flow meter.


Disconnect the air intake tube from behind the passenger-side headlights, unplug the electrical connector on the back side of the air flow meter, then lift the entire assembly out of the car.


This is what your engine bay should look like with the parts out of the way. The spark plug wires are neatly guided through the long rectangular plastic piece over the valve cover.


Here's a closeup of the old wires where they plug into the distributor cap.



The wire guide is attached to the valve cover by two 8mm nuts.


The new set of Bosch spark plug wires. They work fine but lack the aforementioned boot that protects the coil from water splashes. I sent these wires back to get the Beru set ($92 from BMA Auto Parts).


Use a small flat-blade screwdriver to open the little tabs that hold the plastic guide closed.


Remove the plastic cover at the end. Unless yours is more pliable than mine was, you'll need to slice it with a pair of scissors. During reinstalling, we'll tape the cut edge back together with black electrical tape and rotate the seam to the back so it won't be visible.


Install the new wires, one at a time, so that their connection points don't get mixed up. It's easiest to start with the ones on the right side and move your way to the left. The plugs simply pull off by hand.


Clean and reassemble the plastic wire guide then re-attach it to the valve cover.

Finally, replace the last wire which goes from the distributor cap to the coil, located below the front end of the windshield washer pump.

Reinstall the air filter and air flow meter assembly, re-attach the hose clamp. Don't forget to reconnect the electrical connection on the back side of the air flow meter. The car will crank but not start if that connector isn't in place.

David Cecil
'02 X5 3.0, 15k miles
'97 740iL, 120k miles
'86 735i, 94k miles
'77 320i, 140k miles
'92 325is (rear-ended on I285, gone but not forgotten)

www.e38.org has links for everything about your BMW 7-series automobile

• tips on renewing the rotor arm and plug wires please - philipuk 2004-06-10 07:08:46 (488 views)
  • Changing spark plug wires (pic) (url) - davidc 2004-06-10 13:21:20 (5274 views)
    • Re: Changing spark plug wires - kjkumar 2004-06-10 23:42:37 (679 views)
      • Well said Kumar, David's pics and text are really helpful and - philipuk 2004-06-11 03:53:57 (411 views)