eric_in_sd

Well, I got all of about 20k miles before my aftermarket cam housing plugs (https://mbworld.org/forums/gl-class-...ml#post6947349) started leaking.

Because I can never get enough punishment, I bought another aftermarket set. Same maker (Dorman). They were tougher to get in, so I thought I was good. Well, the 1" plugs promptly wandered out, which I became aware of from seeing literal clouds of smoke in my rear view mirror. Not all the way out, but enough to drip oil on the exhaust.

I was in a bind, so I sat down to seriously troubleshoot the situation. The plugs are held in by little plastic snap latches - you know how when you snap-assemble injection molded parts? There's a little barb that snaps into place. Honestly, this is a pretty weak way to hold those things in. I measured the dimension of the barbs, and the new are slightly smaller than the old. I considered bending the plastic outward to make them latch better, but that didn't seem like a good solution. Plastic bent one way can also bend back on its own.

This is a weak mechanism to hold in a precious bodily fluid like engine oil.

I figured a little glue would set this right up. I cleaned the old 1" plugs thoroughly with brake cleaner, and swabbed the opening in the housing (valve cover?) with solvent and brake cleaner. Then I put a bead of silicone caulk around the business end of the plug, and inserted the plugs in the holes. Left it overnight, and no smokey smokey on my road trip the next day.

The caulk is decent stuff, and it's not like the installation is dealing with pressurized oil or anything, but I'm going to redo the sealant installation with Permatex black "gasket maker" silicone just to be safe. Frankly, given the headaches these plugs cause, I'd recommend this solution to anyone replacing them. Just make sure to put the silicone on the plug, not in the hole. That way the extra is pushed out, not in.

Why MB didn't put in old school metal freeze plugs is a mystery to me.

JamesMitchell

Thanks for the info on the cam plugs. I recently had a leaking PVC oil breather, so I decided to replace the breather and the 3 cam plugs at one time. I bought an OEM Mercedes breather on Amazon for $53 and bought the 3 OEM plugs from the local Mercedes dealer for about $22. There were various options to purchase the cam plugs on the internet, but I didn't want to fool around with the cam plugs for another 80-100K miles, so I bought them from the dealer for pretty cheap. So far so good.

eric_in_sd

You won't get 80-100k miles, though. Mine were falling apart at 70k. The plastic gets all brittle. I'd change them on a preventive basis at 50k miles.

You also can check inside the breather tube to see if the separator is doing its job. If the tube is wet with oil inside, the little disc-with-a-hole seal is gone. Of course, if the separator is leaking, it has to be replaced.

Fun note: if you park your truck facing downhill, the oil drips will mostly only be on the road, not your garage floor.