I have a 1993 300E and took it to the dealership because the engine was stuttering. The service department said it needed new plugs and boots for the coils and quoted a repair cost of over $450 which seemed excessive. I am trying to find a repair diagram to replace the plugs and wires, but cannot locate one. Two questions, 1) does this diagnosis sound accurate, and 2) where might I find a diagram so I can replace these items myself?

Any assistance would be greatly appreciated.

Thank you

There are 3 coils, so there are only 3 spark plug wires. The coils have boots that connect to the other 3 plugs.

The valve cover trim panel needs to be removed & you will see hoe SIMPLE replacement really is!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
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1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

...and if you still have a problem, the wiring routing is stamped right in the cover you removed .............

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A Dalton

Would you recommend that I purchase plugs, an ignition wire set, and the ignition coils? I have looked them up using the 'buy parts' link on this site. The MB dealership said I needed new plugs and boot coils. I just want to make sure I am getting what I need.

Any assistance is appreciated. Thank you.

No, you don't want the coils. You want the spark plug connector for direct coil ignition. Look under the "engine electrical" section of the online catalog here.

The engine has three ignition coils, each of which fires two spark plugs. One of the two plugs is connected via the wire. The other, the coil sits directly on top of it. The coil is connected to the spark plug via the spark plug connector. You have to remove the three wires and the three coils and the three spark plug connectors to change the spark plugs. It's at least 10 minutes work, if you take your time.

- JimY

You want 6 plugs and 3 of these.

http://catalog.worldpac.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=2AO123CS42D50MFBWI&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1993&product=F1010-84561&application=000357364

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A Dalton