ignition coils
Thread Starter
Member
Joined: Dec 2024
Posts: 80
Likes: 22
From: 714/949, SoCal
2008 S211 4MATIC
ignition coils
i have 122k miles on my 08 e350 and i'm getting a misfire on cyl 3. i replaced the plugs but the problem remains. coils are next but i ran out of time. i will be swapping the coils around to see if the problem follows the coil!
assuming it's just a bad coil, do i replace just the 1 or replace all 6? in my research i've seen most folks do just the bad 1, and never all 6. then i read that coils are wear items and should all be replaced as the rest will eventually fail. are coils "lifetime" or truly wear items?
assuming it's just a bad coil, do i replace just the 1 or replace all 6? in my research i've seen most folks do just the bad 1, and never all 6. then i read that coils are wear items and should all be replaced as the rest will eventually fail. are coils "lifetime" or truly wear items?
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Joined: Apr 2021
Posts: 846
Likes: 558
From: San Jose, CA
11 E550, 16 AMG GTS, 13 S550
Nothing lasts forever. Coils can last 150k, coils can last 60k. It's all luck of the draw, when you service your plugs and boots, and the condition of your alternator sometimes.
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Purchase Amsoil at 25% off from me
Chris Tran, Retired Alpha European Autotech Owner
Amsoil Independent Dealer #7236674
Thread Starter
Member
Joined: Dec 2024
Posts: 80
Likes: 22
From: 714/949, SoCal
2008 S211 4MATIC
thanks guys! i decided to get all new coils.
new/related question: should i put dielectric grease on the boot tips?
i get mixed answers as well. the delphi coils i received are not pre-greased as some i've read having.
new/related question: should i put dielectric grease on the boot tips?
i get mixed answers as well. the delphi coils i received are not pre-greased as some i've read having.
MBWorld Fanatic!
Joined: Jan 2014
Posts: 3,961
Likes: 1,312
From: Republic of Texas
'99 and '05 E55 AMG
Yes to the dielectric grease. Waterproofs, reduces risk of arcing, and makes it easier to get the boots off the next time you need to change plugs. It's the same reason I use anti-seize on all exhaust components. Eventually, you are going to have to go in there so make it easier for your future self. 
Thread Starter
Member
Joined: Dec 2024
Posts: 80
Likes: 22
From: 714/949, SoCal
2008 S211 4MATIC
thanks for the reply! i added dielectric grease to all boots when i add all new ignition coils. car runs well now! also changed the engine air filters while i was there.
interestingly i noticed the holes at the end of the old boots were slightly larger than the new boots. my guess is that the old spark plug (bosch) ceramics are slightly larger than my replacement NGKs, and molded that way over 100k miles. the grease would definitely help slip over the plugs!
interestingly i noticed the holes at the end of the old boots were slightly larger than the new boots. my guess is that the old spark plug (bosch) ceramics are slightly larger than my replacement NGKs, and molded that way over 100k miles. the grease would definitely help slip over the plugs!
