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Valve Cover Gasket Replacement
 
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Pelican Technical Article:

Valve Cover Gasket Replacement

Tom Morr

Time:

2 hours2 hrs

Tab:

$30

Talent:

**

Tools:

10mm socket, 5mm Allen, E8 Torx driver, rags, cleaner, gasket sealant

Applicable Models:

Mercedes-Benz R170 (1998-04)

Parts Required:

Valve cover gaskets (possible crankcase breather hoses)

Hot Tip:

Clean everything well

Performance Gain:

Cleaner engine

Complementary Modification:

Breather hoses

If you have noticed that the area around your valve cover is filthy with oil there is a very good chance the gaskets are going bad. This is a very common problem with Mercedes SLK230 but not to worry, repairing them is not that difficult and this article will walk you through the steps.

First, work on a cold engine. You are going to need to remove the spark plugs, wires and coils to remove the valve cover

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.

Use a 5mm Allen and remove the two bolts holding the oil separator to the valve cover. Lift the AOS from the engine and remove the oil return line on the bottom, as well as the one connected to the valve cover.

Use a 10mm socket and remove the 9 bolts holding the valve cover to the head. The bolts are a variety of lengths so make a quick outline on a cardboard box to keep them in the proper order for reinstallation.

The valve cover is surprisingly fragile if you start hitting it with a hammer or trying to pry it up with a screwdriver you will probably damage it. NEVER pry between the valve cover and the head, you can cause damage and will end up with a leaky cover. Using a rubber mallet, gently tap around the area where the valve cover meets the head and if you take your time the valve cover will "let go" and you can remove it.

Remove the old gasket around the cover and the four spark plug gaskets. The spark plug gaskets get really baked on and will need a fair amount of work to get them out and cleaned up. Use caution when prying between the seal and the cover.

The valve cover gasket sits in a grove in the valve cover. Make sure you get all of the old gasket out and clean the groove well.

If your spark plug gaskets are like ours you will need to put a little gasket sealant around them to help hold them in place while you are installing the cover. I like to use Curl-T.

If you have properly cleaned and prepped the valve cover and head you do not need to use any sealant. The valve cover gasket will stay seated in the cover while you install it. People tend to go crazy and glob on all kinds of sealant and it just ends up making a mess on the outside and getting into the valve train on the inside.

When you install the valve cover make sure the spark plug gaskets fit flush over the spark plug openings, the gasket sits flush all around the head and the two circular cut out areas in the rear are smooth and flush.

Installation is the reverse of removal. Tighten the head in a criss cross fashion and only torque to 10NM

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 a 5mm Allen and remove the two bolts (red arrows) holding the oil separator to the valve cover.
Figure 8

Use a 5mm Allen and remove the two bolts (red arrows) holding the oil separator to the valve cover. Lift the AOS from the engine and remove the oil return line on the bottom, as well as the one connected to the valve cover (yellow arrow).

Use a 10mm socket and remove the 9 bolts holding the valve cover to the head (red arrows).
Figure 9

Use a 10mm socket and remove the 9 bolts holding the valve cover to the head (red arrows).

The bolts are a variety of lengths so make a quick outline on a cardboard box to keep them in the proper order for reinstallation.
Figure 10

The bolts are a variety of lengths so make a quick outline on a cardboard box to keep them in the proper order for reinstallation.

The valve cover is surprisingly fragile if you start hitting it with a hammer or trying to pry it up with a screwdriver you will probably damage it.
Figure 11

The valve cover is surprisingly fragile if you start hitting it with a hammer or trying to pry it up with a screwdriver you will probably damage it. NEVER pry between the valve cover and the head, you can cause damage and will end up with a leaky cover. Using a rubber mallet (red arrow), gently tap around the area where the valve cover meets the head and if you take your time the valve cover will "let go" and you can remove it (yellow arrow).

Remove the old gasket around the cover (red arrow) and the four spark plug gaskets (yellow arrow).
Figure 12

Remove the old gasket around the cover (red arrow) and the four spark plug gaskets (yellow arrow).

The spark plug gaskets (red arrow) get really baked on and will need a fair amount of work to get them out and cleaned up.
Figure 13

The spark plug gaskets (red arrow) get really baked on and will need a fair amount of work to get them out and cleaned up. Use caution when prying between the seal and the cover.

The valve cover gasket sits in a grove in the valve cover (red arrow).
Figure 14

The valve cover gasket sits in a grove in the valve cover (red arrow). Make sure you get all of the old gasket out and clean the groove well.

If your spark plug gaskets are like ours you will need to put a little gasket sealant around them to help hold them in place while you are installing the cover.
Figure 15

If your spark plug gaskets are like ours you will need to put a little gasket sealant around them to help hold them in place while you are installing the cover. I like to use Curl-T.

If you have properly cleaned and prepped the valve cover and head you do not need to use any sealant.
Figure 16

If you have properly cleaned and prepped the valve cover and head you do not need to use any sealant. The valve cover gasket will stay seated in the cover while you install it. People tend to go crazy and glob on all kinds of sealant and it just ends up making a mess on the outside and getting into the valve train on the inside.

When you install the valve cover make sure the spark plug gaskets fit flush over the spark plug openings (green arrows), the gasket sits flush all around the head (yellow arrow) and the two circular cut out areas in the rear are smooth and flush (red arrow).
Figure 17

When you install the valve cover make sure the spark plug gaskets fit flush over the spark plug openings (green arrows), the gasket sits flush all around the head (yellow arrow) and the two circular cut out areas in the rear are smooth and flush (red arrow).

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Comments and Suggestions:
Trooper Comments: I have solved my spark plug gasket mystery, and offer this in case it should be helpful for others: I purchased a new valve cover which was obviously much better made and finished than the old one I was working with. Rather than bare metal or that awful tan paint job, it was well-cast, smooth, and finished a shiny gray that compliments the front engine cover. The spark plug gaskets fit perfectly and seated flush with the bottom of the cover without any extra effort at all. Even though I had thoroughly cleaned the orifice for each spark plug in the original valve cover, and could actually see and feel the "rim" that the gasket seats in, the orifices on the old cover were 1-2 mm smaller in diameter, as measured by caliper, than the new cover! The more closely I compared the two valve covers, the happier I was that I had fractured the old one, as it was a complete piece of junk compared to the new one, and had obviously been very poorly made. I know the covers aren't cheap, but if you are wrestling with your spark plug gaskets, you may have an older cover in which they just plain don't fit. I hope this helps.
October 13, 2016
  Followup from the Pelican Staff: Thanks for the follow up, i was waiting for the author to get back to me about your questions. Appreciate you clearing it up and sharing what you found. Makes the articles better for everyone. - Nick at Pelican Parts  
Trooper Comments: I am a little or a lot! confused. You mentioned with Figure 15 that a little gasket sealant might be needed to keep the spark plug gaskets in place, but in the photo they are clearly not fully seated. Is Figure 15 indicative of how far you were able to press them in by hand? Fully seated gaskets appear as in Figure 13, but they do not require anything to help keep them in place. I have found it impossible to seat them by hand, and fractured the valve cover when trying to drift them in with a socket set-up similar to the drift tool. I can't imagine that torquing down the valve cover would seat the plug gaskets, and if you installed per Figure 15, I would expect massive oil leakage around the plugs. Please help me understand this better. Thank you.
October 6, 2016
  Followup from the Pelican Staff: Your find" I have solved my spark plug gasket mystery, and offer this in case it should be helpful for others: I purchased a new valve cover which was obviously much better made and finished than the old one I was working with. Rather than bare metal or that awful tan paint job, it was well-cast, smooth, and finished a shiny gray that compliments the front engine cover. The spark plug gaskets fit perfectly and seated flush with the bottom of the cover without any extra effort at all. Even though I had thoroughly cleaned the orifice for each spark plug in the original valve cover, and could actually see and feel the "rim" that the gasket seats in, the orifices on the old cover were 1-2 mm smaller in diameter, as measured by caliper, than the new cover! The more closely I compared the two valve covers, the happier I was that I had fractured the old one, as it was a complete piece of junk compared to the new one, and had obviously been very poorly made. I know the covers aren't cheap, but if you are wrestling with your spark plug gaskets, you may have an older cover in which they just plain don't fit. I hope this helps. - Nick at Pelican Parts  
Muratti Comments: As per WIS a drift tool 111589041500 is needed to properly seat the plug seals in place. When installed they should look like fig13. So I think you cannot fit them just with your hands. Seal has a sort of metal ring which enlarges to the edge. This is the hardest part of the job.
May 29, 2016
  Followup from the Pelican Staff: I have installed without the special tool, it can be done.

Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Topper242 Comments: Yeah, what is torque on the bolts for this project?
April 19, 2016
  Followup from the Pelican Staff: I don’t have that info.


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
 
Bill Comments: Wonderful information and pictures. when installing spark plug gaskets
"What tool should I use to place the gaskets into the valve cover Figure 15

Thank You for your help.

Bill
December 10, 2014
  Followup from the Pelican Staff: Just press them in by hand. - Nick at Pelican Parts  
Usmc-guy Comments: What is the torq on the bolts for this project. Well done!
October 19, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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