The GLK normally sits in the garage - it's rare it's parked outside. So yesterday, I moved it outside to sweep out the garage.
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I noticed a slight oil stain (actually 2, but one is more prominent). Photo below (glove there to show size). It's not a major stain, as if oil was spilled.
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I decided to do a quick investigation, opened the hood and took off top-front engine cover, then grabbed the oil filter housing.
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it was loose !!!! It took about 2-3 clockwise turns till it was tight and seated. I then checked the oil level (3-4 times), it's at the top of the gauge range (as it should).
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I then drove up to the local gas station for some beverages (2.5 mile drive there). Got in GLK, started, backed up a bit and got out to see if any evidence of oil drip - yes !! Guessing about 4-6 tablespoons worth - a tiny puddle, 1/2 the size of the palm of hand.
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So drove home and parked (still running), and checked filter housing - still snug. Looked underneath truck - very slight drip forming off lower engine cover - nothing like a constant drip.
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Turned off, waited 10 minutes - checked oil level - still at the upper end of range. I did clean the upper engine and inner fender area (degreaser), then hosed it down. Waited till it dried, then started it and watched from open hood down - no obvious oil drizzle.
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My theory is what is dripping is oil that has accumulated on the bottom engine cover when the loose filter housing was leaking oil. Today, I'll remove the lower engine cover to investigate more fully, ie , the drain plug. I will also clean the lower covers and lower part of engine area.
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So my big question is - is there anything else I should be aware of? Like an oil sending unit / sensor (etc) that might also be slightly leaking (while I investigate the drain plug etc,)?? Anything else??
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Sorry so wordy - I get detail oriented sometimes.
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You’re lucky you caught it before the cap fell off , that would have been very bad, messy and possibly a fire . Maybe a lost motor or vehicle. That’s about all the turns that keep it on!

 

After having that much oil leak out onto your engine (and engine compartment items), it's gonna drip for a while. I'd suggest either just waiting a few months and ignore any (non-huge) signs of drips, or cleaning your engine compartment completely (including those splash covers), and then re-checking after a couple weeks of driving.

 

I prefer the 'clean it now' option. Once you've determined the actual leaking part(s) is fixed, I would clean anything that can be cleaned below that area. The lower engine covers are kind of a PITA to remove, but it's a good idea to check from underneath and make sure there are no other areas leaks are occurring from. A good pressure wash of those lower covers will help you identify any future issues the next time you check them.

On another note, how would an oil filter housing get loose over time? Has it been replaced? And when you tightened it back up, did you add any lock-tite to the bolts? Or was it just oil filter cap that was loose?

 

I did the clean it now approach. Removed lower cover and degreased it, washed off, then dried. Same with lower engine area.
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Came back 30 minutes later, opened hood, then fired up engine, then looked around for leaks - I began top-side ... Found it. Even though the filter housing was snug, there was a slight seepage coming out between the plastic filter housing outer lip and the aluminum filter housing (that's attached to front of engine). See photo - I marked where oil was weeping from.
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So I removed the plastic filter housing, knowing the o-ring is probably nicked ... I see no evidence of it. I checked the filter housing for signs of a crack, or anything else ... nothing - looks fine. I took off the o-ring and checked it - seems in order to me. I've yet to check the aluminum housing.
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So anyway, I'll take this opportunity to get a new filter (comes with new o-rings), and do an oil change (while lower covers and filter housing are off). Then I'll do the start it and watch for the leak thing.
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BTW, @andreigbs, not sure what bolts you're referring to ... to change the filter, simply unscrew its plastic housing, drop new filter in, then screw housing back over it.
The only bolt to remove is the oil drain plug
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I doubt it dripped 4-6 tablespoons. That's a LOT of oil. 4 tbsp ~= 60cc. A little bit goes a long ways...

 

From your initial post, it wasn’t clear if the oil filter housing was leaking. If so, it is held on by bolts and probably a gasket between it and the engine mating surface.

Based on your description it seems your leak is from the oil filter cap itself.

A new set of filter gaskets should do the trick, and properly torquing the cap.

 

I’ve never had a Mercedes leak from the oil filter cover. But my grandson had a Ford Eco Boost engine that did it constantly. On close inspection, the cover had been cross treaded at some past time and it deformed the seal. A new filter cover fixed it.

 

I just had this problem, and the reason was that the oil filter housing o-ring gasket was not seated in the proper position. Sometimes 'professional' mechanics do this too. The interesting thing was that it takes 20-30 mins for the oil pressure to build up to loosen the oil filter and blow out most of the oil in the pan.
The oil leak is probably all over the block. You can have the GLK put on a lift and someone with a steam cleaner can remove all of the spilled engine oil after the plastic shrouds are removed. Otherwise it will may drip and smoke for many hundreds of miles.

 

Personally, I have absolutely no idea. It's been in place for quite a while (since last oil change), which is a good reason to do the oil change now. Maybe it was a suggestion
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But yea, this could have turned out to be a catastrophic event. Knowing me, I'll be paranoid after the oil change: "should I check the filter housing?" after every drive.

 

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Wow, @Discod ... another victim? Believe me, the housing gasket was in its proper place! When I took off the housing earlier, that was my first check, "gotta be the gasket". It was there, as it should, and has no deformity that I can see (except I guess just "worn out").
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The oil remnants were concentrated on the right side (looking down) and mostly lower end. When I saw the leak earlier, it was barely noticeable. But everything is cleaned up now, so just need to drain and fill, plus new filter.
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BTW, your comment:
"oil pressure to build up to loosen the oil filter"
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Can you elaborate - is this something to be cognizant about, after starting the engine, before driving away??
(not sure what "loosen the oil filter" is suggesting)

 

Whoever did the last change didn’t tighten it enough, since you say it was 2-3 turns loose and probably didn’t replace the gasket or position it properly. Just check it after a few days for oil. The cap needs to be tight. Not hand tightened, but wrench tightened. There is probably a torque requirement.

 

Correct - the torque is in plain view on top of the filter housing:
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Final analysis? Only a best guess on my part, but based on what I remember.
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Worn out o-ring for the plastic filter housing. When I recently discovered it was loose, and screwed it back down, I was able to seat it by hand, with no challenge.
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When I screwed down (by hand) the housing with the NEW o-ring, lots of resistance. (yes, I oiled it). After the housing was seated, I used a dedicated filter wrench cap and torqued to 25.5 Nm.
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It's been 9,000 miles since last oil / filter change. Maybe should do it at 6,000 miles

 

What torque wrench does .5 Nm? My Sears beam-type (no clicks) can do +/- 5 anyways. In the decades I've owned it Sears even replaced it for free once when the gauge plate fell off the front. *sigh*

 

I have two torque wrenches - one is a 1/2" drive 10-150 ft-lbs and the one I used for filter housing is a Craftsman 3/8 drive 10-80 ft-lbs "DigiTork" wrench. Some classify it as vintage It's not a true digital as we think of in 2024. Shockingly, I looked on eBay just now and saw one listed for over $200 usd.
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... see image - the bottom of handle is the adjuster - you pull down and turn to desired reading, and it snaps back into a locked position.