Does anyone have information on replacing the valve cover gaskets? It's my understanding there are some small but extremely important details to follow (such as not using any gasket maker I believe?).

 

The VC gaskets are rubber, so for the most part they don't use sealant. There's two spots at the front of each cylinder head where the head meets the front engine cover, I put a tiny bit of RTV sealant on these areas, just a thin smear across the seam.

Other than that, I don't recall anything terribly special.

Of course there's removal and installation of the coil packs which is its own procedure. Note the different bolt lengths and their locations, be careful and patient pulling the coil packs away from the spark plugs. If you don't know the age and condition of the spark plugs and their silicone boots, I'd recommend you go ahead and replace them while you've got it apart.

You'll have to remove the cast aluminum radiator hose neck, note that in addition to the two obvious bolts on top, there's a bolt holding this neck to the front engine cover that's somewhat hidden underneath. You'll want to drain the coolant from the radiator before you do this; you could probably get by with draining just a quart or two.

I completely removed both intercooler cores when I did mine. You might be able to pull them up out of the way while leaving the coolant lines connected and so avoid having to fill/bleed the intercooler system; I went ahead and removed mine because I knew my system needed a fill/bleed procedure anyway and it just seemed like it'd be less frustration to have them completely out of the way. Cover your turbo inlets and outlets while you've got the air cleaners and intercooler cores out, you don't want to drop something in there.

Be careful with torquing things down when you reassemble. Most of the bolts involved are only 6mm thread size, going into aluminum, so it's easy to go too far. Torque spec for the valve cover bolts depends on your engine number; it's either 9nm, or 4nm + 120 degrees. My general approach to aluminum threads is to use a small dab of medium strength Loctite, then tighten the bolt down just until it feels snug. The Loctite helps to avoid the urge to over-tighten in an attempt to prevent stuff from coming loose.

That's all I can think of, pulling from memory.

 

Hey Bruce, thanks for the help and the video.

I got the coil pack out, and only noticed a very small leak at the gasket (I had previously only tightened the bolts), and it took care of most of the leak. I will be replacing the spark plugs on that side. I'm debating if I want to continue with the entire valve cover now, or see if I can put some rtv on the outside to stop the small leak. I know it's not the proper way to do it, but if it alleviates the issue, then I would be satisfied.

 

Found an interesting article while googling:

https://agradetools.com/5-reasons-wh...s-a-dying-art/

 

No. This will not work.

 

Correct, you cannot seal an oil leak by applying RTV externally.

These engines generate a LOT of heat, which tends to cook the VC gaskets causing them to shrink and become hard/brittle.

Each valve cover has a cam position sensor at the rear which protrudes into the cover by a fair amount. When you remove the valve cover, it will not lift straight up off the head, it'll hang at the rear - you'll need to lift it slightly to loosen the cover/gasket from the head, then slide the cover back towards the rear by about 1-2 inches so the the sensor clears the valvetrain. It can be tricky to get the valve cover installed while keeping the new gasket in place, so when you're ready to reassemble, I'd suggest you rehearse the motion of sliding the cover into place a few times without the new gasket installed so that you've got the procedure down to a smooth motion with little or no unnecessary contact.

Once the valve cover with new gasket is in place, inspect the full perimeter to make sure the gasket hasn't slipped out of the valve cover slot anywhere. Use a small mirror to check around the back near the cam sensors, when I did mine the gaskets were prone to slipping out of the slot at the rear corners.

 

I've decided not to do the valve cover. The oil leaking is minimal, and not enough to be a problem (snaking its way into the coil pack).

I've now found something I'm a bit more concerned about: oil in the intercooler and turbo intake side area. The passenger side is squeaky clean.

 

That's normal for the M275. Crankcase ventilation is handled through the left side intake. If it's excessive, it's most likely the centrifugal oil separator that sits on the front of the left valve cover. But a little bit of oil in that left turbo inlet is nothing to worry about. "Excessive" = blue exhaust smoke, left bank oily spark plugs, left bank ignition misfires.

 

Oh that's CRANKCASE ventilation!

I was wondering why I didn't see anything similar on the passenger side bank.

About to put everything back together after having changed the spark plugs. They needed changing because the valve cover had leaked oil into the threads, and I didn't do all of them for some reason when I tightened the valve cover bolts. I found the small amount of oil leaking to be at an acceptable level.

 

Ehhh....... any amount of oil leaking down onto the plugs is not really a great idea. The M275 uses the spark plugs as misfire and knock sensors, so if oil gets in between the plug/head threads it can cause the grounding for the plug to be a little off. Not necessarily enough to prevent a spark, but enough to cause the misfire/knock reading to be off and throw a code.

Personally, I would not leave even a small valve cover leak active if I already had the coil pack out. Aside from the hassle of having to do it all over again if you run into drivability issues stemming from weird misfire/knock readings, you just really don't want to be removing/installing those coil packs any more than necessary. They're kinda fragile, people have broken them when trying to remove them.

At the very least, be sure to put a thin coat of dielectric grease on your silicone spark plug boots, both inside and out, so that the coil pack will come out easily next time.

 

By acceptable level, I mean *very* minimal. Close to zero. I know how the m275 uses the spark plugs. Dielectric grease is a good idea.

 

I have a quote from the dealer telling me I need to replace head front cover cylinder gasket left and right- cover is leaking oil.
I am at about 100k miles.

I have a personal friend/mechanic who does the oil changes, tires etc and is verypartial to American cars so he grinds his teeth everytime he helps me LOL Anyways, is this something that would be out of his league or I would want dealer to do? Dealer quoted 1400 to do left and right... most of cost is in labor.

Thoughts?

Gasket, Cylinder Head Front Cover - Replace. (Left side front
cover leaking oil). 566.90
Gasket, Cylinder Head Front Cover - Replace. (Right side front
cover leaking oil). 734.56




Each valve cover has a cam position sensor at the rear which protrudes into the cover by a fair amount. When you remove the valve cover, it will not lift straight up off the head, it'll hang at the rear - you'll need to lift it slightly to loosen the cover/gasket from the head, then slide the cover back towards the rear by about 1-2 inches so the the sensor clears the valvetrain. It can be tricky to get the valve cover installed while keeping the new gasket in place, so when you're ready to reassemble, I'd suggest you rehearse the motion of sliding the cover into place a few times without the new gasket installed so that you've got the procedure down to a smooth motion with little or no unnecessary contact.

Once the valve cover with new gasket is in place, inspect the full perimeter to make sure the gasket hasn't slipped out of the valve cover slot anywhere. Use a small mirror to check around the back near the cam sensors, when I did mine the gaskets were prone to slipping out of the slot at the rear corners.[/QUOTE]

 

You probably want to ask over in the forum for your vehicle - GLK Class (X204)
This forum is for the V12 twin turbo found in CL, S, and SL class cars (and a few rare G wagons). Completely different engine and procedure from your vehicle.

 

I just recently changed out the valve cover gasket in my w220 s600. It was pretty easy and straight forward. Only annoying part was having to remove the hard pipes for the intercoolers. Everything else was fast and easy. I recommend doing this if you have already removed the coilpacks. It really only takes 30 minutes more to do. I torqued the bolts to 9ft lbs. Since it's only the valve cover you don't have to worry about torturing the bolts in sequence but don't over torque, you will strip the threads.

 

did you mean 9nm? 9 ft/lbs would break those aluminum bolts I’d think.

 

Yes, your right. It was 9nm which converts to 6.6381 foot lbs. I tried to get it as close to 6.6lbs as possible but ended up torquing some closer to 7lbs