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Hi,
After noticing a burnt oil smell when driving, I tried to investigate and found a few things. Looks like the engine valve cover might have an oil leak. But what do I know...) I definitely spotted a leak on the oil housing cooler, leaking front and back and under.. Cleaned it a bit to see if it'll come back, so it won't look much of a leak on that part it on the pictures below. I'm wondering however if it's not 'splashing' on the cover behind it, so it could still be the problem.
But then also I discovered leaks on the right (passenger side) engine cover too.
Any input on that anyone?
Rudeney, MB master, what do you think?
Here are pictures. On the passenger side it's under the bar mostly, the dark spot. On the driver's (USA driver), it's on the front. Behind the oil housing mostly.
I bought the car knowing there was a leak that can be seen on the inside of the 'car belly', the engine splash cover. But never saw it dripping on the ground from there. It looks like an accumulation over time. I can't see any dripping. Just the burned oil paste. Smell it when I drive.
I'm not a mechanic and know very little, so I apologize in advance for the lack of technical vocabulary.
Driver side:
Behind the oil housing Clean the oil cooler a bit but had burnt oil too.
On the passenger side now: Can't see super well but the dark is not a shadow it's all oil paste. Oil is right in the middle of this picture under that metal bar. Dark is all burnt oil Oil under and between these two guys From afar it can be seen under the air hose. Under the hose
Looks like it has been leaking and baking oil for awhile. The oil on the oil cooler side is likely the oil cooler. It could be the gaskets inside the cooler are shot or it could be a crack in the cooler housing, generally caused by overtightening the oil filter housing onto the oil cooler. I assume you just recently bought the car. If you have not changed, or had changed, the oil you might also check that the O-ring in the housing (new ones come with the filter) is properly installed and not pinched.
The oil on the passenger side could be coming from the oil fill cap. The seals get worn and leak, particularly with spirited driving. Depending on how back the seals and or the pressure spring are the oil could spray back over the valve cover. You can sometimes rotate the fill cap 180 degrees (the oil logo is upside down) to slow the discharge while you wait for a replacement.
If oil is on the rear of the engine on the passenger side, it could be from the air/oil separator at the rear of the engine. Mine failed a couple years ago and pooled oil on the intake manifold.
You could have one or more of these problems, if the car was not being properly serviced. It could also be the valve cover gaskets, but I would check those other possibilities first, even if you have to take it to a service shop. You can check the things I mentioned yourself.
Hi,
Thank you so much for your input. So you don't think it's the engine valve cover? Even on passenger side? I had wondered too, since I'm pretty sure there's a link from the oil housing, if it could be spraying on the surrounding parts. It's true that the oil is right next behind. But that doesn't explain the passenger side. The leak isn't on the rear. I checked the cam covers and the separator a well. If you look on the pictures 'passenger side' it's located under that bar. The oil housing had no contact there. Do you think the cap could spill that far? I'd be sorry lucky ending with changing an oil cooler gasket and an oil cap!!! )
Let me know.
Thank you for your time and help.
The valve covers on these engines almost never leak. Instead of a rubber gasket, they use a very high-temp, high-strength RTV sealant that almost never fails.
As Fatz suggested, the oil cooler and oil filler neck seals can leak. Also, on your engine, common sources of oil leaks are the seals on the front of the camshafts where the adjuster solenoids are located. Also, on the back of the camshafts, on the left side there are "plugs" that are known to leak, and on the right side, there is a plug and the oil centrifuge that can leak. With all the oil on the front of the engine, I suspect the camshaft adjuster solenoid seals, which is Scenario 3 on the "balance shaft" TSB:
I think you should check those things I listed as possible sources and those listed by Rodney. After some lengthy spirited driving some time ago, I noticed an oily spot on the hood liner. It was over the oil cap. When I changed the oil cap 3-4 years ago there was oil farther back on the valve cover (passenger side). And there was the smell of burning oil. I believe the caps are designed to release pressure above some level. Weakened components of the cap (seal and retaining arms) can allow release prematurely -
Thank you so much guys! Great advices.
I'll get a new oil cap.
I also found this link (see below), magnets and seals for cheap OE, might as well go for it. I'll probably need the oil cooler seal replaced as well. From the look of it, it's got to be the magnets leaking like Rudeney said. But since I found oil around the cooler too, you're both right.
I wonder if the position sensor plugs needs seal replacement as well, do they often leak too?
Looks a DIY but I don't have the place or equipment so...
I found torque specs for the magnets at 10 NM same for oil cooler bolts. Am I correct?
Looks like it won't require a MB certified mechanic for these as it looks simple enough. Though I'm not sure it goes as easy on the passenger side...
I found a video DIY but for the driver side. Btw, for those who only need adjusters resealed/replaced, it looks like the magnets can be replaced without removing the steering reservoir and the oil cooler. Not a lot of room but possible apparently.
The seals on the camshaft position sensors don't usually leak, but they are only a few dollars each, so you might was well replace them while you're in there. Also, the oil cooler will need to be removed to replace the left-bank camshaft adjuster solenoid that sits behind it, so plan on replacing that seal even if you think it's not leaking.
Hi,
I looked directly on my engine to see the installed part, the oil housing says #2721800510.
At FCP, looking to buy the part, it says it doesn't fit my 2007 clk550 though. see link below. Any idea why?
https://www.fcpeuro.com/products/mercedes-engine-oil-cooler-sl550-mer-2721800510
Other thing is, on one of the pictures in this thread, the leak on the passenger side is right below the fuel rail and also between the intake manifold switchover diaphragm but no leak around the oil cap, I don't understand what can trigger so much cooked oil under the fuel rail or right between the switchover. (The driver side though is definitely a leak from solenoids and oil housing)
Any idea?
Thank you.
Last edited by alexandergreat; 11-17-2018 at 02:05 AM.
What is the "switchover"? I probably should know but I don't...……. Have you checked the AOS (Air/oil separator)?
The oil separator yes, that one of the question I have. See my post further above about part number. Seems like it's not the right one or fcp got it wrong...
"The oil on the passenger side could be coming from the oil fill cap. The seals get worn and leak, particularly with spirited driving. Depending on how back the seals and or the pressure spring are the oil could spray back over the valve cover. You can sometimes rotate the fill cap 180 degrees (the oil logo is upside down) to slow the discharge while you wait for a replacement. " - FATZ
Yes. Thank you. I did that.
What do you think about the link I sent? They said it won't fit but that's the actual part number it came with...
Thanks a lot.
My money is on the camshaft adjuster solenoid seals.
On the driver side, yes. I'm just surprised that on the passenger's there's not much of a leak around these, but I guess oil just sprayed further away and landed under the fuel rail. There's no oil in this area anyways, from what I know, unless...from camshaft bolts...dunno. Looks like it's mostly fuel and air related parts around there so...
Between the switchover though, yes, it must be the adjusters. Besides, It's a known leak so..
Thank you guys. That was really helpful, thank you so much.
Random question: is it normal to lose a little bit of coolant say 3~5mm (don't know how much in ml, maybe 1/4 cup) lower in the expansion tank after heavy traffic, 45 min bumper to bumper..?
I know it's off thread, but I was looking nationwide for CLK 550 coupe, and noticed there was less than 7 for sale (even less from 2007). I looked on multiple websites, not many at all. How comes is this car so rare in the states (world??)? Anybody knows?
I don't know what is it about this car, but I'm just crazy about it. I bought it not long ago and want to have it in perfect condition. I wanted to clean the engine bay which as you can see on the pictures is filthy, but I'm worried about electronic and electrical components...
So... anyways...why is this car so rare?
Arf...have so much to discuss and ask...
Thank you mb rockstars!
Last edited by alexandergreat; 11-17-2018 at 09:11 PM.
1985(W126)500SE, 1994(W124)E420 1991(R129)500SL and The Mothership 2009 CLK550
Hello Alex I don't have the mechanical aptitude to be of help with locating that pesky oil leak, but your last paragraph above caught my eye, because I also adore the body style and design of the CLK500/500, such that I would probably choose a CLK 550 above all other cars new or used, even if money was no object and I could drive anything I wanted.
Sometimes I just sit and admire the lines of my 2009 CLK550, as it sits outside my house, and I marvel at the precision German engineering that created this unassuming, low-key, Clark Kent, guided stealth missile of the highway. The CLK may not be capable of keeping pace with a newer V8 Merc, or a Porsche on a race track, but this car is capable of unleashing far more horsepower than I will ever need, which is what counts. Anyway, enough pointless rambling from me, for now ha ha.
Hello Alex I don't have the mechanical aptitude to be of help with locating that pesky oil leak, but your last paragraph above caught my eye, because I also adore the body style and design of the CLK500/500, such that I would probably choose a CLK 550 above all other cars new or used, even if money was no object and I could drive anything I wanted.
Sometimes I just sit and admire the lines of my 2009 CLK550, as it sits outside my house, and I marvel at the precision German engineering that created this unassuming, low-key, Clark Kent, guided stealth missile of the highway. The CLK may not be capable of keeping pace with a newer V8 Merc, or a Porsche on a race track, but this car is capable of unleashing far more horsepower than I will ever need, which is what counts. Anyway, enough pointless rambling from me, for now ha ha.
I completely agree at every levels!!! I'm crazy about this car. You'd actually be surprised about how newer mercedes or Porsche and such are actually slower on a 0-60 run and lower in hp, or more importantly in my opinion in torque! I envy you, a 2009 must have everything optimized and the known problems mostly fixed.
I'm very thankful I found this forum. People like Rudeney, and others great people have provided me with great advices. And I'm grateful for that. They're amazing. That car got me into learning mechanics. Lol.
What part of the world do you live in? LA here.. I have not to this day, seen another CLK 550 coupe or even convertible for the matter...
11-09-2018, 01:44 AM
) I definitely spotted a leak on the oil housing cooler, leaking front and back and under.. Cleaned it a bit to see if it'll come back, so it won't look much of a leak on that part it on the pictures below. I'm wondering however if it's not 'splashing' on the cover behind it, so it could still be the problem.
