Mercedes-Benz Parts Catalog Mercedes-Benz Accessories Catalog Mercedes-Benz Technical Articles Mercedes-Benz Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Spark Plug Wire and Coil Replacement
 
Bookmark and Share

Pelican Technical Article:

Spark Plug Wire and Coil Replacement

Tom Morr

Time:

2 hours2 hrs

Tab:

$40 to $150

Talent:

**

Tools:

E8 Torx driver, 5mm Allen, 5/16th spark plug thin wall socket extensions

Applicable Models:

Mercedes-Benz R170 (1998-04)

Parts Required:

Spark Plugs, wires, coils when necessary

Hot Tip:

Work on a cold engine

Performance Gain:

Better mileage

Complementary Modification:

New air filter

Replacing the spark plugs on your Mercedes-Benz SLK230 is recommended routine maintenance. Mercedes recommends replacing the spark plugs on SLK230 models every 100,000 miles or five years. With all the major engine design changes over the years, spark plugs now last up to three times as long as they did in years past. I suggest replacing your spark plugs every three years regardless of mileage. If the last time they were serviced is unknown, replace them right away. I do NOT recommend putting anti seize on the plugs.

It is a very good idea to change the plugs when the engine is cold. If the engine is hot or warm the threads in the head a much more susceptible to damage from stripping or cross threading.

The spark plugs, coils and wires for the SLK230 are all located on the top of the engine under a vanity plate. Remove the three bolts holding the plate to the valve cover with a 5mm Allen.

With the plate out of the way you can see the coils, wires and plugs. Two of the plugs are connected directly to the two coils and two plugs have individual wires running to them. There is a rubber grommet at the rear of the cover that helps seal out the elements from the coils along with plastic harness guides to keep the wires in place.

The coils are held in place by two E8 Torx screws on each coil. Remove the four screws. With the screws removed lift coil with the spark plug connector attached straight up and off the plug.

Next remove the two wire and connectors going to the other two plugs by pulling the connector straight up with a slight twist. Never pull the connector up by the wire!

With everything freed up set the entire harness on the top of the engine so you don't mix them up when it comes to reinstallation. Make sure to vacuum and clean the area around the plugs as you don't want dirt of debris falling into the motors combustion camber when you remove the plugs.

Use your 5/8 thin walled spark plug socket along with a long extension and remove the plugs. Note: when reinstalling the plugs it is always best to hand thread the plugs until you are sure they are properly seated.

Examine the plugs for any issues with the motor. These plugs look OK but slightly towards the engine running lean. This could mean an O2 sensor or MAF starting to go bad.

Inspect the wiring harness and connectors for any damage, fraying, cracks or signs of arcing and replace as needed. If you are replacing the wires and connectors remember that the front plug connects to the rear coils and the rear plug connects to the front coil.

Installation is the reverse of removal.

The spark plugs, coils and wires for the SLK230 are all located on the top of the engine under a vanity plate.
Figure 1

The spark plugs, coils and wires for the SLK230 are all located on the top of the engine under a vanity plate. Remove the three bolts (green arrows) holding the plate to the valve cover with a 5mm Allen.

With the plate out of the way you can see the coils (yellow arrows), wires and plugs (red arrows).
Figure 2

With the plate out of the way you can see the coils (yellow arrows), wires and plugs (red arrows). Two of the plugs are connected directly to the two coils and two plugs have individual wires running to them.

There is a rubber grommet (red arrow) at the rear of the cover that helps seal out the elements from the coils along with plastic harness guides (yellow arrow) to keep the wires in place.
Figure 3

There is a rubber grommet (red arrow) at the rear of the cover that helps seal out the elements from the coils along with plastic harness guides (yellow arrow) to keep the wires in place.

The coils are held in place by two E8 Torx screws on each coil.
Figure 4

The coils are held in place by two E8 Torx screws on each coil. Remove the four screws (red arrows).

With the screws removed lift coil with the spark plug connector attached straight up and off the plug (red arrow).
Figure 5

With the screws removed lift coil with the spark plug connector attached straight up and off the plug (red arrow).

Next remove the two wire and connectors going to the other two plugs by pulling the connector straight up with a slight twist (red arrow).
Figure 6

Next remove the two wire and connectors going to the other two plugs by pulling the connector straight up with a slight twist (red arrow). Never pull the connector up by the wire!

With everything freed up set the entire harness on the top of the engine so you don't mix the connector to plug up when it comes to reinstallation (red arrows).
Figure 7

With everything freed up set the entire harness on the top of the engine so you don't mix the connector to plug up when it comes to reinstallation (red arrows). Make sure to vacuum and clean the area around the plugs as you don't want dirt of debris falling into the motors combustion camber when you remove the plugs (green arrow).

Use your 5/8 thin walled spark plug socket along with a long extension (red arrow) and remove the plugs.
Figure 8

Use your 5/8 thin walled spark plug socket along with a long extension (red arrow) and remove the plugs. Note: when reinstalling the plugs it is always best to hand thread the plugs until you are sure they are properly seated.

Examine the plugs for any issues with the motor.
Figure 9

Examine the plugs for any issues with the motor. These plugs look OK but slightly towards the engine running lean. This could mean an O2 sensor or MAF starting to go bad.

Inspect the wiring harness and connectors for any damage, fraying, cracks or signs of arcing and replace as needed.
Figure 10

Inspect the wiring harness and connectors for any damage, fraying, cracks or signs of arcing and replace as needed. If you are replacing the wires and connectors remember that the front plug connects to the rear coil (red arrows) and the rear plug connects to the front coil (yellow arrow)

Bookmark and Share
Comments and Suggestions:
karl Comments: verry helpfull
December 15, 2015
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
RTTucson Comments: Do you stock the gasket that fits under the spark plug vanity plate? I can't find it anywhere!
June 19, 2015
  Followup from the Pelican Staff: I am sure we do.

Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Fufu Comments: How often to change plug wires? M113 v8 5.0 engine. Clk500. Thanks in advance
May 22, 2015
  Followup from the Pelican Staff: Every 60 - 100k, depending on climate and condition. - Nick at Pelican Parts  
Olav Comments: Thanks a lot for your reply. This is what I found out:

NGK: 10-12 Nm on their home page
Beru: 25 Nm as printed on the box
October 20, 2014
  Followup from the Pelican Staff: Great! Thanks for the follow up. - Nick at Pelican Parts  
Olav Comments: Which torque is recommanded for installing new spark plugs?
October 11, 2014
  Followup from the Pelican Staff: I think 25Nm. However I am going by memory.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Mon 12/5/2016 02:25:29 AM