Rudeney

First of all, do NOT use any sealant on the head cover gaskets. You just need the gasket and that's all. Of course the breather covers do not use a pre-made gasket, they use only an appropriate RTV sealant.

I re-used the valve cover bolts when I did this on my C240. I actually did the job twice because the first time I used Victor Reinz gaskets which are too thin and leaked. I then used the genuine MBZ gaskets and all was well. There is no indication in WIS that the bolts need to be replaced. Just use the proper torque on them - 9 Nm for the head cover bolts, 8 Nm for the coil pack bolts.

I'm not sure about the plugs, as there are many version that will work. There are platinum, iridium, split style, quad style, etc. Resistor plugs are no necessary, but they are helpful in reducing electrical noise. My understanding is that most modern platinum and iridium plugs are "resistor" type.

NickLouis

Yeah that's what I thought. I was confused looking at the pictures with gasket sealant being applied to the rubber gasket. What does WIS say about the breather cover screws? Do they supply a part number?

Rudeney

I believe the breather cover bolts are N000912005010 (3 on the left ban, 4 on the right). The cover bolts are two sizes: A0019908322 (7 left, 9 right) and A0019908422 (4 left, 2 right). But like I said, these do NOT require replacement.

tw2

Valve cover bolts are re usable. Looks like zinc coated steel to me. I got new aluminum breather cover bolts from the dealer with me C32. When I went back for them for the CLK they said they don't exist. I didn't use any sealant on the valve covers. Only the breathers.

I reused the breather cover bolts with no problems. Just clean them well and torque correctly.

Rudeney

Given the low torque values on these bolts, even if they are aluminum, there is no reason to replace them. Like I said, even WIS does not call for them to be replaced, and MBZ is usually very conservative on things like this.

Timewarpone

Great Instructions. Now I am confident I can do it myself because of your detailed write up. I will also change the plugs. My dealer wants over $800 just to do the valve cover gaskets. I drive a 05 CLK320 with 102k miles. Both valve cover gaskets are seeping oil. No performance issues as of yet. I bought both Mercedes Genuine OEM gaskets from parts.com for $42 and 12 OEM Bosch plugs (7422) FR8DPP33 on ebay for $56 (Free S&H, No Tax). What do you suggest I use to clean the oil off of the outside of the valve covers? Also how long should I wait after I apply the sealant before I start using the car?

Rudeney

When I did mine, I just used a generic engine degreaser spray to clean the cover. Microfiber towels also do an amazing job of cleaning up oil. Since the covers use a pre-formed gasket, there's really no concern about a small film of oil its surfaces. In fact, some say it's best to coat the gasket with a light bit of fresh oil to help it seal better. The breather covers use RTV, so their mating surfaces need to be grease-free. I used a quick-flashing contact cleaner (MAF cleaner would work, too) for that.

Gersh320

I also used ATF sealer for the breathers. When I do it again, I will use the original MB sealer because mine started seeping after just a few thousand miles. Very little but still frustrating.
I let mine sit for about 15 hours or so before I started the engine. They sit far less than that when shops perform the work though.

Timewarpone

Where can I get the ATF sealer and what brand, Thanks. I am still waiting for the parts to arrive so I should be able to change the gaskets within the next 2 weeks.

Timewarpone

My breather covers are not leaking should I do them anyways?

floridawriter

It's a good idea to at least check over the crankcase vent tubing and ensure that the 1.5mm port on the right-hand passenger breather box is not blocked by sludge or carbon. Oil collects inside the vent boxes and drains back down into the valve covers through small holes, 4 on the passenger side and I believe 5 on the driver side. If those holes get blocked the oil will get sucked into the intake system and your car will use excessive oil and run poorly. Also you will collect water vapor which will cause sludge. So given all this, if you are changing out the valve coover gaskets it's good preventive maintenance to do the breather covers as well.

I'd recommend getting the Mercedes RTV not an aftermarket type product. Just my 2 cents.

Gersh320

Great advice Florida.

Get the sealer from your MB dealer. While you are at it, the rubber hoses connected to the breathers should be replaced. I didn't buy them at first. They become brittle with age and when removing could very easily tear (mine did). Again, inexpensive parts that will make your job a lot easier. Think of it as new arteries for your car :-)

Timewarpone

My local Autozone rep recommended Permatex Ultra Black gasket maker. Should it be silicone based or not? Your thoughts please. Thanks
Also I don't mind changing the 3 hoses that attach to the valve covers. Makes sense and they are not that expensive. So I should look inside the breathers on top of both valve covers to see if those drain holes are blocked?

floridawriter

Stick with what works and get the Mercedes RTV.

Rudeney

I used a black RTV sealant I bought from autohausaz. It's an aftermarket version of the MBZ sealant. It worked great and has been holding for years now.

Timewarpone

Is it absolutely necessary to remove the oil filler neck? Will the valve cover come off with this intact? Thanks

Gersh320

It will come off with the filler neck attached. I replaced the rubber seals on that as well... the cap too. I tend to go overboard a bit

Timewarpone

I am leaning towards removing the breather covers after I remove the valve covers. It can't hurt to look inside to see if anything is clogged. What is the recommended torque wrench setting when I put the bolts back on? Thanks

tw2

You really need to remove both the breather and valve covers at the same time as they share some of the main bolts. If you loosen one then the seal will be broken and most likely won't reseal again without being cleaned and replaced. I think the torque is 5Nm for the main bolts, 2Nm for the aluminum ones.

Timewarpone

It took me 6-1/2 hours to change my valve cover gaskets and spark plugs, earlier today. I took my time and I took a break for lunch. I did way more cleaning then turning a wrench. The passenger valve cover gasket leaked more oil than the driver side. The only problem I had was removing the drivers side sparkplug nearest the firewall. It was a real PITA to remove. Took me over 20 min. I replaced the sparkplugs with Bosch Double Platinum 7422 and I also used genuine Mercedes gaskets. I did not use any RTV Gasket Maker on the gaskets. Just a thin film of clean oil. These are the best gaskets I have ever seen or used. Way better then the thin cork ones I have used in the past. Sorry tw2, I did not remove the breathers. I didn't see your post until I was all done. They were not leaking but I will keep a close eye on them. The torque settings I used were 9NM for the Head cover bolts, 8NM for the Coil Packs and 28NM for the spark plugs. That is what Bosch recommended. It is printed on the side of the spark plug box for my plugs. I want to personally thank everyone and anyone who had any input on this thread. You gave me the confidence to go forward and succeed. The car purrs like a kitten!! and no leaks, so far.

DanielFD

your engine's camshaft is new! WOW.. I've never seen a M112 with such clean insides. did you clean them or were they like that? how many miles on the car?? Also updated blue fuel injectors. those are expensive!

Scratch that, just saw you have 102,000 Miles on it. Thats still soo clean for an engine with that mileage.

Timewarpone

I was surprised on how clean the insides were also. I did not clean them. I guess using Mobil 1 0w-40 really does pay off. The valve cover gaskets really needed changing especially the passenger side. I also changed the oil filler neck gasket and the oil cap gasket. I did not remove the breather covers. So far no leaks anywhere. I check daily

Rudeney

That's odd, Mobil 1 0w40 usually causes all the parts to take on a golden tint, like this one:

CLKINDIVIDUAL

So I ply out the spark plug wire was pretty tuff but why is it so easy to plug it back in? Or do I need to force it in more?

tw2

More force. Push as hard as you can on one of the easier front ones until you feel an obvious click. For the back ones I needed to use an 18" screwdriver with a socket taped to the end to use as a lever against the frame to push them home properly. I used brand new bosch leads. If you can pull it off reasonably easy it wasn't on properly.