07 GL450, 39k miles

Oil leak on Left (driver's) side, on back of engine, from the little square plastic box which is in the center of camshaft (it's next to the round plastic plug). How should I replace it? Do I need to remove the valve cover? If someone knows or may be has an illustration/diagram, I would like to print it. Thanks in advance.

 

I had my GL450 at the dealer for another issue and they replaced the cam plugs under warranty. On the repair ticket, the cause was listed as "bulletin".

 

Under warranty the following was done on my 2007 GL450:

"Per DTB: S-B-01.30/23B Replaced expansion plugs on rear of left and right cylinder heads."

A000 998 55 90- 2 small expansion plugs
A000 998 56 90- 1 large expansion plug (engines without vacuum pump)
No sealer should be used in the installation of the new plugs.

 

I looked again today (this time from top of engine) and the leak is coming from the bigger plug. (See images below). The square plug/cap is on the right, not left.... on the left there is a smaller and bigger round plugs. I used degreaser then put some silicone to temporarily seal it until I get the part ordered. Still do have the question of how this plug comes out?

 

Mine were replaced last week while it was in to replace a leaking rack. Seems to be a common problem.

 

take a flat screwdriver and pop it off. you should go ahead and replace all three. putting it on is a little trickier as the holding clips are very fragile..

 

Bought the cap... $7.00. Replaced. 10 minutes of labor and no need to remove valve cover.

 

I did this too, as my GL450 was leaking from 2 of the 3 caps. Bought the caps from the MB dealer for $15, and did the work myself. Took about an hour, but if I did it again I could do it in 20 minutes. The dealership wanted 1.3 hours for an MB tech to do this!!

Steps:
1) Remove sway bar. This is easy, just 2 16mm bolts on each side, and then a small 10mm screw on the top of the left side. You may need to bang it loose once you have the bolts out, but it comes out pretty easy.
2) Remove the 2 plastic engine covers. The front one just lifts off, but the back one is a little trickier. It connects in 3 places. There is an air intake on each side that you can either pull out from the front of the car or where the hose comes into the cover. I looked for the path of least resistance and that was one of each. Finally there is a hose that connects in the middle. Just pull that out. Once you have these undone, the piece just pulls up.
3) Replace the cam plugs. They are all on the back of the engine, but if you are tall you can peek over and see them. There are 2 on the right (one big, one small), and one small one on the left. I popped them off with a screwdriver. The new ones just push on. Be careful, the clips are fragile.
4) Now is a good time to replace the air filters. The cover you pulled off has 2 filters housed in it. Flip it upside down and you will see that each box has 4 star screws to remove. I replaced mine with Hastings filters, though to be honest they didn't fit perfectly well. Weird. Has anyone else had that issue? The foam seems a little big.
5) Replace the plastic pieces, ensuring to reconnect all 3 intakes.
6) Congratulate yourself for saving $150 in labor.

 

Ours started leaking through rear plugs, dealer took care of problem and gave us an E350 loaner. Our dealer is new here and is making a great impression.

 

You guys are great. I have this same problem, same side, same location on my 08 C350. I was really worried this was going to hurt my pocket book, but now I see its nothing. Thank you very much.

 

Are these also known as the "cam covers"?

 

On my C350 there are 4 total. 2 smaller plugs that are used to adjust the cam in the back and 2 cam covers in the front. In 170k miles only the rear ones have leaked which are the cheaper ones.