Mercedes SLK World banner

Status
Not open for further replies.
1 - 9 of 9 Posts

·
Registered
Joined
·
161 Posts
Discussion Starter #1
I have read all of the tune up guides that I can find on here and have a few follow up questions. This is my first attempt at anything remotely mechanical in nature, so please hang with me.

Dealership wants $1000 to do the tune up and the certified mechanic wants $600. Parts are only $255 so I figured now was a good time to get under the hood and figure it out for myself. Dealer states 3, 4, and 5 are misfiring and the valve cover gasket is leaking. Car was at the dealership for an insurance related repair. They replaced the wiring harness. Now that the wiring harness has been replaced and the computer is functioning again, the car is now misfiring, which was not happening prior to the wire harness repairs. Dealer states this "new issue" is basic maintenance and has nothing to do with the wiring repair.


Replace spark plugs and wires:
Tools

One of the threads said to use a 17 mm wrench to remove the wire boot. Another said it was definitely worth it to buy the special boot tool. So I have one vote for regular wrench and one vote for the special tool. Anybody used both and have feedback on one vs the other?

Dielectric Grease

Put on the spark plug head and in the boot. How much, a little or a lot? Does any go on wire end that gets attached to the coil?

I have a feeling that the misfire issue is being caused by oil that has leaked down into the spark plugs, causing misfire. If I find oil on the plugs when pulled, how do I clean the holes that the plugs are removed from ( do those holes have a name?)

Valve Cover Gasket

There was a suggestion to use non-silicone gasket sealant. There was no specific details given other than that. I purchased Permatex- Ultra rubber gasket sealant and dressing. Is this what I need or do I need something that is for high heat environments? The only high heat stuff I have found states it is silicone based.


Finally, how do I clean all of the oil that has leaked off of the engine?

Thanks for any help you guys can provide to this newbie.
 

·
Registered
Joined
·
136 Posts
From my experience, the special plug boot removal tool is a modified 17 open end wrench. I bought it online through Amazon. However I only needed it for the rear plugs (at the corners near the heat shielding).
I used anti-seize on the sparkplug threads but no dielectric grease on the boots. Perhaps I should have, and might still do that. Should only need just enough to seal out fluids. I think the coil pack connections are sealed up okay with their rubber gasket, so probably not necessary to apply the dielectric grease.
The dealer told me that my valve cover gaskets needed replacing and breather caps needed re-sealing. I chose the DIY route too.
I found that the breather caps just needed the Permatex "The Right Stuff" for resealing, they do not have gaskets.
So far I have chosen not to replace the valve cover gaskets as the seepage is not very bad (also an '01 SLK320, w/ 117000+ miles).
While replacing the sparkplugs a few months ago, I cleaned off the covers by first using a plastic blade and rags to get the thick deposits, then engine degreaser sprayed onto a cloth to wipe off the oil and grease residue.
I never sprayed the degreaser onto the engine. I also used an nylon brush and a can of air duster to clean out some of the cavities.
Sorry no advice about the misfire - good place to start by pulling the plugs, and you should check for codes too.
If you post the codes here there are others that can give better advice.

Good luck with the tune-up. My plugs were in awful tight and had to use a lot of force to get a couple of them out. I was scared the plugs were going to bust off in the heads! They might have been the originals.
 

·
Founding Member #2 2008 SLK55 AMG
Joined
·
19,407 Posts
I think a proper torque wrench too when tightening the spark plugs. Someone may have the torque specifications for the specific R170 model.

The anti-seize compound should be high-temperature (IIRC, PropDr had some recommendations).
 
  • Like
Reactions: BluBenz

·
Premium Member
Joined
·
1,314 Posts
Plugs are an every five year/100,000 mile job. Mercedes wires last a long time. I found the wrench helpful when removing the wires. The proper tool is the old valve adjustment wrench from a 1970's era Mercedes. I was able to borrow one from a friend. Anti-seize on the threads is not approved by Mercedes, but a lot of people do it. Your torque value will not be accurate when using anti-seize. Use the recommended plug. Dielectric grease not needed, but if you do use it, use it like Brylcreem, i.e. a little dab will do ya.
 

·
Registered
Joined
·
136 Posts
I think a proper torque wrench too when tightening the spark plugs. Someone may have the torque specifications for the specific R170 model.
The torque instructions that came with the FR8DPP33+ Bosch plugs simply said to tighten 90° after seating them.
I used these Platinum Iridium plugs after reading about other forum members having good results with them.
 

Attachments

·
Registered
Joined
·
161 Posts
Discussion Starter #7
Thanks for the input. Went back and re-read the Bosch plugs. No anti-seize needed. Seems they come Pre-designed/Pre-coated to naturally break free without a lot of issue when time to remove.

XOFMOT-the product you referenced is a gasket maker. I have ordered the replacement gaskets, so I just need sealant to help seat them and to increase the sealability. Do I still need to use a gasket maker as well as the gaskets themselves?

Any help with how to clean out the cylinders should I find oil of the spark plugs?

Thanks again
 

·
Premium Member
Joined
·
1,314 Posts
AFAIK Mercedes valve cover gaskets are put on dry, i.e. no gasket maker, no gasket sealant. You need to verify that with the service manual though. Do as it says and don't try to outsmart the designer. :)

You are correct on the thread coating on the Bosch plugs.
 
  • Like
Reactions: DIYGirl and etyu

·
Registered
Joined
·
579 Posts
To clean up the oil, use Super Clean, found at your nearest, Napa, Autozone, Advanced Auto parts, or Pepboys! :) Everyone likes a clean oil-free engine!
 
1 - 9 of 9 Posts
Status
Not open for further replies.
Top