In January I replaced my E39 M5 spark plugs. Over the past few months I’ve given the car a complete tune up, minus an oil change it doesn’t need yet. In BMW lingo this equates to an Inspection II, which would have cost $1,200 or more at a dealer or independent shop.
Last summer I changed the fuel filter and the transmission fluid. Over the Thanksgiving weekend my car had a misfire on engine cylinder two. I cleared the code and it didn’t happen again, but the misfire made me realize it had been over 50,000 miles since the spark plugs had been replaced by a previous owner. While doing the plugs I decided to change the cabin and engine air filters and remove and clean the Mass Air Flow (MAF) sensors.
Spark plug replacement on an 8-cylinder BMW engine is more complicated than on a 6-cylinder. I changed the spark plugs on my E36 M3 back in 2012 and it was pretty straightforward. When you remove the engine cover on a 6-cylinder the plugs are right there in front of you.
On the V-8 engine the spark plugs are lower and on each side of the engine. I purchased an 11 inch spark plug socket with a swivel head and magnetized to keep the spark plug in place during insertion. Fortunately I was able to borrow a long, magnetized 10mm wobbly socket along with a power gun. That made it a lot easier to reach and remove all the 10mm screws that held the injectors in place without dropping any into my engine bay. Bimmer Werks in Beltsville, Maryland was our host garage and owner Amr was generous with his time and assistance.
Doing some research on the right parts to purchase saved me a lot of money. I replaced both the spark plugs and the boots, the rubber cylinders that attach the spark plugs to the coils. Parts branded as BMW are much more expensive, even for identical parts from the same manufacturer. For example, the eight NGK plugs I bought were $5.99 each, and the Bremi boots were $4.59. The same parts BMW branded were $18.29 and $22.44 each, respectively.
The one replacement ignition coil I bought as insurance for cylinder 2 was $42.99 from Bremi directly, $94.72 from BMW. And with the Bremi you got a new boot included! The filters had similar price differences. In total I paid $159.41 for parts. Had I gone with genuine BMW it would have cost me over three times as much, $483.49. Here’s a detailed explanation of Original Equipment (OE) parts vs. Genuine BMW from FCP Euro, an excellent source for parts.
I found it easiest to remove everything first – disconnect the coils, remove their bolts and push back the plastic piece that holds the wires. There are three grounds on each bank to undo as well. There was no oil on the boots or plugs – if there had been, that would have meant the valve cover gasket needed to be replaced.
When inserting the new plugs with socket start them by hand to make sure they are threading properly. It’s not hard to crack the block if you tighten the plugs too much. According to the Bentley manual only 22 ft. pounds of force is needed. A fellow CCA member lent me a torque wrench to use and I set it at 20.
Some pictures below, click to enlarge. I hope they help anyone replacing their E39 M5 spark plugs. I’ll never have to do spark plugs or transmission fluid on this car again based on the miles I drive annually. But something else is sure to need attention.
Cover removed exposing coils
Coils removed passenger side
Old and New Spark Plugs
New Boots (on left)
Sparks plugs are way down there, I used a 6 inch extension with the 11 inch socket wrench
Out – note wiring harness
Hoses partially block access to cylinders 7 and 8 on driver side
New Air filters, one each side
MAF sensor unplugged and removed, requires 5 point security torx bit
Sensors – let cleaning spray dry completely before starting car
Chris – your last sentence “…something else is sure to need attention.” Ha! Wait til you try replacing cam position sensors. Both on Bank 1 are easy. But then there’s Bank 2, especially the exhaust CPS, a real gem. I struggled mightily with that one, and learned some swear phases too! Tip: If you do these in the future replace the Allen head screws that hold them in with standard hex head fasteners. I believe they’re M8.
Throttle position sensors (aka TPS) is same story – Bank 1 easy, Bank 2 not so much. FCP Euro has best price for all of them. Ones I bought were the OE parts with the BMW logo ground off.
I put up some posts with pics from my work on the M5Board forum – my user ID is swingwing. I sold my ’02 2 1/2 years ago to try my hand at first Porsche, an ’09 911 Carrera. It’s a nice car but I do miss the Beast.
Nice to hear from you Vic! And thanks for heads up. If and when those issues crop up I’ll make sure I’m surrounded by fellow enthusiasts at a CCA DIY event. Enjoy the P car.