karayjay

Mystery oil leak help so I find myself every three weeks my oil light comes on check oil now it seems like it’s happening more frequently here’s the problem I don’t see any oil on the ground I don’t see any oil coming out of the exhaust I know strange now I work on car so I know these things pretty well there are those two plastic caps on the rear of the cylinder heads those of been replaced and I don’t feel any oil and usually when oil drips from there if it’s the exhaust and you can smell it burning since I’ve capitals

Yidney

I assume you are talking about your 2007 350. Doesn't that car have a dipstick? So how much is the oil down on the dipstick each time you get the message? Have you gone under the car and removed the belly pan? Any oil there? How much oil you are actually losing is as important, or more important, than the fact you are getting a warning. Maybe the level sensor is bad and you are not losing any oil.

Fatz

It sounds, from your description, that I have the same thing occurring. I've assumed that the engine is just burning a bit of oil. Since the car has 136K miles on it and I rarely drive with the RPM very far from 2000, I am ok with less than a quart of oil every 2-3 thousand miles. It may call for a top off sooner if I engage in more than usual "spirited" driving...

I don't plan to do anything about mine, except top it off when needed. I may have it analyzed before I do any expensive mods; probably next year sometime.

karayjay

Has anybody tried rear main seal leak stop additives do they work do they harm I mean I don’t mind trying it but my fear is will it hurt and make things worse that obviously none of us want anybody ever have any experience with this because I’m telling you I put a half a quart in a week ago and the light came on again indicating that I’m going to oil so it’s happening more and more frequently before used to be three weeks now it’s two weeks and now it’s coming down to one week this is not cool there’s nothing on the ground

Yidney

Are all the punctuation keys missing from your keyboard? You didn't answer any of the questions asked, but now you are asking about stop leak? Why? If your rear main seal is leaking that much oil you would be able to see it easily. There are always weep holes for it to escape where the engine meets the tranny.

Fatz

I don't think there is anything magical happening..... If there is no oil spills on the engine (valve covers), or on top of the intake manifold, at the back of the engine (plugs), or on the belly pan (as Yidney said) or floor/ground, the oil is either being burned or going into the cooling system.

I assume you're not seeing smoke from the exhaust.....

If it were me I would check all those visuals for oil and I'm not planting my right foot frequently, I would take it to a qualified shop for an answer.
What's the mileage?

karayjay

NO oil on the ground, no oil in the coolant AKA( head Gasket.) I did replace the 3 caps on the end of the he CLY heads last year. I replaced the cam plugs and Centrifuge cover. I park in the same spot each day at work no oil on the ground...I am baffled ans it seems to be getting worse.

gaazmon

In the 6 digit territory, I have noticed the 550 engine (assume same for 350) likes to "eat" more oil than our previous 320 and 500 vehicles. At 10,000 miles, I notice about a quart of oil eaten versus on the m112/m113 engines it was about half a quart. I don't find this odd on the m272/m273 engines as these are very strong and higher output engines with more intricacies compared to their replaced counterparts. I have two friends with older Infiniti G35s and every 5,000 miles they notice a quart or so "missing". The computer says 13k service intervals on these MB vehicles, but I believe the newer 10k intervals are more proper and would go with that.

Yidney

OK, but have you removed the belly pan? And do you have a dipstick? And how many miles? My wife's XC90 had a main seal leak for years and there was never one drop on the garage floor. It just sat in the belly pan. So step one is to remove the belly pan and look for leaks. If the belly pan is dry, and you give the engine a careful inspection from the front to where it mates with the tranny, and you see no fresh oil, and it's not in your coolant, then you are just burning it.

Rudeney

+1 to removing the lower engine cover. You;d be surprised at how much oil those covers can contain without dripping.

gaazmon

Agree. I've experienced this first hand on a previous Benz.

karayjay

Don’t I have one of those on mine and I’m the second owner I’ve had this car since it had 22,000 miles on it my other vehicle the W208 Clk320 and he hast a plastic cover so I know what you’re talking about but this one does not have one

Rudeney

So your MY2007 CLK does not have a set of plastic covers under the engine and part of the transmission? Then it is missing. The car some from the factory with these covers.

Fatz

Even if the underside covers are missing, you should see oil on the underside of the engine, transmission and other parts, as the air flow would spray the oil as it drips. Are you saying there is no oil on the underside from the radiator back?

If you've checked all the things listed, the people on the forum can move to other possibilities in their attempt to help.