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Mercedes Valve Cover Gasket Replacement
 
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Pelican Technical Article:

Mercedes Valve Cover Gasket Replacement

Steve Vernon

Time:

4

Tab:

$26

Talent:

**

Tools:

T-25, T-30, E10 Torx driver, rags, cleaner

Applicable Models:

Mercedes-Benz ML320 (1998-03)
Mercedes-Benz W203 (2001-07)

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 your valve covers are filthy with oil there is a very good chance the gaskets are going bad. This is a very common problem with Mercedes C320s but not to worry, repairing them is not that difficult and this article will walk you through the steps.

You are going to have to remove the engine air ducts and covers to get access to them.

Remove each duct by compressing them towards the engine and slipping them off the air inlet.

With the ducts off remove the front engine cover. It pulls up and away from the engine. The cover is held on by five clips and will easily come off with hand pressure.

Next, you will need to remove the main engine cover that also houses the air filters. It is held on by four pressure clips. You can see the two at the front of the engine, to remove the housing lift it at the front of the engine and once the front clips release the rears (which you can not see) will release as well.

We are going to begin with the right side covers. You will be able to see the valve covers on top of the heads, they hold the coils.

Disconnect the individual wiring harnesses going to each coil, there are three of them. They simply squeeze in and pull out of the coil.

Next, remove the crankcase breather hose from the breather cover. If the hose is fairly new it should slide off. If the hose is original or old there is a very good chance it is dry and brittle and you are going to damage it and need to replace it. Do yourself a favor and order new hoses before you start this job.

Use a T-30 Torx and remove the bolts holding the coil packs in place. With the bolts gone you can just swing the coils out of the way.

You do not need to remove the wires and boots from the plugs but now is a good time to take them off and clean them. The boots can be very tricky to remove and will take a little patience, especially the ones at the rear of the motor. The boots are on quite snug and you will need to use a 17mm open end wrench to place over the end of the boot and using the valve cover gently pry the boots off. If you want to make the job very easy Pelican sells the Hazet tool that is basically a specially bend open ended 17mm wrench that makes getting the boots off a ease and you can use them to help seat the boots when you reinstall them. Note: NEVER try and remove the boots by pulling on the wires, you will only end up ripping the wires from the boots!

Remember the while the coils are interchangeable the wires from each coil must go to the appropriate plug. With the coil mounted on the cover the "A" wire always goes to the forward plug.

Next you will need to use an E10 Torx driver and remove the 9 bolts holding the cover on.

You may have to wiggle the covers around to get the seal to break loose to remove the cover. Do not hit the cover or try and jam a screwdriver between the valve cover and head as this can damage both causing them to leak even more. Remove the old gasket and clean the area. You do not have to clean every where (unless you are going for a concourse look) but you do need to clean off all of the old gasket and clean any areas that mate.

Install the new gasket into the valve cover and reinstall on the head making sure it sits flush and does not fall out, especially on the rear.

The left side of the engine is similar with the exception of two breather hoses and the top rear bolt has a mount attached to it, other than that the procedure is the same.

Installation is the reverse of removal.

You will need to remove the two air inlet ducts (red arrows) as well as the front engine cover (yellow arrow) to get access to the air filter housing on top of the engine.
Figure 1

You will need to remove the two air inlet ducts (red arrows) as well as the front engine cover (yellow arrow) to get access to the air filter housing on top of the engine.

Remove each duct by compressing them towards the engine (red arrow) and slipping them off the air inlet.
Figure 2

Remove each duct by compressing them towards the engine (red arrow) and slipping them off the air inlet.

With the ducts off remove the front engine cover.
Figure 3

With the ducts off remove the front engine cover. It pulls up and away from the engine (yellow arrow).

The cover is held on by five clips (red arrows) and will easily come off with hand pressure.
Figure 4

The cover is held on by five clips (red arrows) and will easily come off with hand pressure.

Next, you will need to remove the main engine cover that also houses the air filters.
Figure 5

Next, you will need to remove the main engine cover that also houses the air filters. It is held on by four pressure clips. You can see the two at the front of the engine (red arrows).

To remove the housing lift it at the front of the engine and once the front clips release the rears (which you can not see) will release as well (red arrows).
Figure 6

To remove the housing lift it at the front of the engine and once the front clips release the rears (which you can not see) will release as well (red arrows).

The two red arrows show the valve covers on each side.
Figure 7

The two red arrows show the valve covers on each side.

We are going to begin with the right side cover.
Figure 8

We are going to begin with the right side cover. You will be able to see the valve covers on top of the heads; they hold the coils (yellow arrows). The breather hose is located just above the coils (red arrow).

Disconnect the three individual wiring harnesses going to each coil (red arrows).
Figure 9

Disconnect the three individual wiring harnesses going to each coil (red arrows). They simply squeeze in and pull out of the coil. You can see how filthy the valve covers are in this picture.

Next remove the crankcase breather hose from the breather cover (red arrow).
Figure 10

Next remove the crankcase breather hose from the breather cover (red arrow). If the hose is fairly new it should slide off. If the hose is original or old there is a very good chance it is dry and brittle and you are going to damage it and need to replace it. Do yourself a favor and order new hoses before you start this job.

Use a T30 and remove each bolt from the three coil packs (red arrows).
Figure 11

Use a T30 and remove each bolt from the three coil packs (red arrows).

You do not need to remove the wires and boots from the plugs but now is a good time to take them off and clean them.
Figure 12

You do not need to remove the wires and boots from the plugs but now is a good time to take them off and clean them. The boots can be very tricky to remove and will take a little patience, especially the ones at the rear of the motor. The boots are on quite snug and you will need to use a 17mm open end wrench to place over the end of the boot (red arrow) and using the valve cover gently pry the boots off.

If you want to make the job very easy Pelican sells the Hazet tool that is basically a specially bend open ended 17mm wrench that makes getting the boots off (red arrow) an ease and you can use them to help seat the boots when you reinstall them.
Figure 13

If you want to make the job very easy Pelican sells the Hazet tool that is basically a specially bend open ended 17mm wrench that makes getting the boots off (red arrow) an ease and you can use them to help seat the boots when you reinstall them. Note: NEVER try and remove the boots by pulling on the wires, you will only end up ripping the wires from the boots!

Remember the while the coils are interchangeable the wires from each coil must go to the appropriate plug.
Figure 14

Remember the while the coils are interchangeable the wires from each coil must go to the appropriate plug. With the coil mounted on the cover the "A" wire always goes to the forward plug.

Next you will need to use an E10 Torx driver and remove the 9 bolts holding the cover on.
Figure 15

Next you will need to use an E10 Torx driver and remove the 9 bolts holding the cover on. You may have to wiggle the covers around to get the seal to break loose to remove the cover. Do not hit the cover or try and jam a screwdriver between the valve cover and head as this can damage both causing them to leak even more.

Remove the old gasket (red arrow) and clean the area.
Figure 16

Remove the old gasket (red arrow) and clean the area. You do not have to clean every where (unless you are going for a concourse look) but you do need to clean off all of the old gasket and clean any areas that mate.

You do not have to clean every where (unless you are going for a concourse look) but you do need to clean off all of the old gasket and clean any areas that mate.
Figure 17

You do not have to clean every where (unless you are going for a concourse look) but you do need to clean off all of the old gasket and clean any areas that mate.

Install the new gasket into the valve cover groove (red arrow) and reinstall on the head making sure it sits flush and does not fall out, especially on the rear.
Figure 18

Install the new gasket into the valve cover groove (red arrow) and reinstall on the head making sure it sits flush and does not fall out, especially on the rear.

The left side of the engine is similar with the exception of two breather hoses (red arrows) and the top rear bolt (yellow arrow) has a mount attached to it, other than that the procedure is the same.
Figure 19

The left side of the engine is similar with the exception of two breather hoses (red arrows) and the top rear bolt (yellow arrow) has a mount attached to it, other than that the procedure is the same.

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Comments and Suggestions:
Pat Comments: what is the torque spect for bolts on valve covers. E320
November 28, 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
 
Jim Cullum Comments: I need to replace a hydraulic lifter on a 2004 Mercedes C240. Can I do this without removing the head?
July 7, 2016
  Followup from the Pelican Staff: I believe so.
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
 
Bernard Comments: I want to wash C240, 2004 model engine. Can I wash it? If so how?
July 3, 2016
  Followup from the Pelican Staff: Has to be cleaned by hand, wiping it down rags and cleaning solution. Do not we the engine. - Nick at Pelican Parts  
Mercedes c240 2002 Comments: This article is so helpful, but i have a question ... some folks use a sticky spry to hold the gasket in its grove while reinstalling the cover again .. do you think it's a good idea ? .
February 27, 2016
  Followup from the Pelican Staff: I never use adhesives on gaskets, unless called for by the manufacturer. They can cause the gasket to slip when tightening. - Nick at Pelican Parts  
Sammy Comments: How do you monitor the current draw on the negative cable after 15 minutes or more to be sure?You are a very big help to all asking for help. Thank you. You are an ANGEL.
November 18, 2015
  Followup from the Pelican Staff: You can use a DVOM on amps in series or an inductive clamp. - Nick at Pelican Parts  
Dan Comments: Once the valve cover is off, how do you replace the hydraulic valve lifters?
April 15, 2015
  Followup from the Pelican Staff: The valve train (rocker arm) assembly has to be removed. We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

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
 
king Comments: Just replaced the valve gasket on Right side . Made sure gasket was flush when installing. Now its leaking at the same spot as before. Could if be the actual cover needs to be replaced??
March 27, 2015
  Followup from the Pelican Staff: I would remove the valve cover and check the sealing surfaces using a straight edge tool. - Nick at Pelican Parts  
maabadilla Comments: Can you please post also the process for the the SLK320 year 2001
December 3, 2014
  Followup from the Pelican Staff: We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.
- Nick at Pelican Parts
 
Mel Comments: I have a 2006 C350 4matic, want to repa;ce valve cover gaskets. Does this tread apply to my vehicle as well? Also what is the torque spect for bolts on valve covers.

Thanks, Mel
November 20, 2014
  Followup from the Pelican Staff: This tech article applies to:
C320 (1998-2004)
E320 (1998-2004)
S320 (1998-2005)
ML320 (1998-2003)
CLK320 (1998-2004)
SLK320 (1998-2003) - Nick at Pelican Parts
 
bishop Comments: Pls must you replace the gasket with a new one or the old one can still serve. Cos my mech said if we open up we must get a new gasket.
September 23, 2014
  Followup from the Pelican Staff: Always replace gaskets when a component is removed that requires one. - Nick at Pelican Parts  
sher hussain Comments: so nice and clear thanks man
September 17, 2014
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.

- Nick at Pelican Parts
 
simple723 Comments: What's the torque specs on all the valve cover/ breather bolts ?
August 4, 2014
  Followup from the Pelican Staff: I don't have those handy.

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
 
Rocky Comments: Hi I have a ml 320 1999 got an oil leakage in between
The serpent belt it's just a little cover with two
Screw on the side how to stop the leakage?
August 1, 2014
  Followup from the Pelican Staff: Replace the gasket behind the cover. Can you share a photo? I can be more specific once I see the leak. - Nick at Pelican Parts  
Phuong Comments: How do you replace the breather cover?
July 13, 2014
  Followup from the Pelican Staff: Remove the fasteners, remove cover, replace seal. - Nick at Pelican Parts  
Phuong Comments: On figure 10, on top of the valve cover, there is another piece. It is beneath the red arrow. What is that piece called? It seems that oil is leaking from there too in my engine.
July 4, 2014
  Followup from the Pelican Staff: That is the breather cover. - Nick at Pelican Parts  
Damian Comments: I have a 1999 CLK 320. there is a wire which seems to run under the intake manifold. How is it removed for replacement? This is the only wire from the wiring loom I cannot figure out how to remove. It disappears by the thottle body.
April 15, 2014
  Followup from the Pelican Staff: What wire are you referring to? An electrical harness wire? - Nick at Pelican Parts  
Cupertino Comments: Hi Nick
How do I MONITOR the draw on the battery ?
thank you.
February 13, 2014
  Followup from the Pelican Staff: With vehicle off, shut all doors and latches. Monitor the current on the negative battery cable. The vehicle will need to go to sleep, about 15 minutes before you get a powered down reading. - Nick at Pelican Parts  
Cupertino Comments: Great tutorial, more clear than youtube.

A side note, my 2001 ML320 has the same engine, battery dies if I dont drive it for 3-5 days. After I jump start it, it be fine until I leave it for 3-5 days,
Any idea?
February 12, 2014
  Followup from the Pelican Staff: You may have a parasitic draw. You'll want to monitor the draw on the battery when the vehicle is asleep. - Nick at Pelican Parts  
lourance Comments: How to clean the old gasket which product are you using and I made test to my engine putting water on the top of gasket filling there is leak my car is C240 w203 2001 the car have noise and movement specially at the N and p your advice
January 30, 2014
  Followup from the Pelican Staff: I prefer to use a plastic scraper to clean the sealing surface. Then a light duty cleaning solvent. - Nick at Pelican Parts  
Andrew Comments: How do you remove the hoses on the driver's side if they are the inflexible type? Do you just "man-handle" them with a wrench or something? Thanks.
November 29, 2013
  Followup from the Pelican Staff: The hose should pull straight off. You shouldn't need any additional tools. - Nick at Pelican Parts  
MLM Comments: Thank you.
September 5, 2013
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help. - Nick at Pelican Parts  
MLM Comments: What happens if you fail to replace the valve cover gasket for so long that your 1999 S320 is loosing oil although not visible on the ground and has to have oil added every month? I am looking at buying one in this condition but wonder if long term damage may have occurred that is not readily visible now I took it to a mechanic to evaluate and he discovered the valve issue - the owner said she has not done anything about the oil loss because she can't see oil on the garage floor.
August 29, 2013
  Followup from the Pelican Staff: I would have a mechanic inspect the oil leaks if you don't see anything, (before you buy it). If the engine was run low on oil, it could have worn components and could now be using oil (buring it).- Nick at Pelican Parts  

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