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I'm sure I'm not the only one who has seen this. M273 car, bought it 6 days ago. Previous owner said the check oil warning will come on when driven on the highway but this is because the mechanic added "too much oil" and said, no problem, it'll burn off. Well, the story is the car doesn't really use oil and it's been like 4000 miles and the warning comes on because the level is too high. This checked out until I looked into it more.
First, aside from my sheer shock that MB installed a dipstick in this car, the oil monitoring system is NOT the same as what I am used to in my E55. It's just a dumb float sensor from what I could glean from WIS. Meaning it has two states. Oil level OK and oil level low. The computer is monitoring while the car is being driven and must use RPM and stuff to determine if the level in the sump is OK or not. And it thinks mine is not.
Second.....well, it just doesn't seem low. Checked hot after a 5 minute sit and the level is like 3/4 up the cross hatch zone. Doesn't seem low to me.
Third, and I think this is a distraction, the PO loved labels and labeled that the car takes 8.5 qts. WIS says 9 qts. Kind of odd but he used various mechanics for service so I'm not sure why he bothered labeling unless he was under the impression that someone had been adding too much oil. Maybe the sensor has been bad for years and no one ever thought to replace it.
So I ordered a new sensor. Has anyone run into this? Am I missing something? The system doesn't seem that complex and also doesn't seem capable of reporting an issue with too much oil. Do the sensors commonly go bad? Car has 79k but the last 18k miles were added over 10 years so I guess it sat a lot, if that matters.
on mine its comes on as the level is 1/2 ltr low - due to the car burning oil - mine ALWAYS does it once the oil has done 2 years or 10k miles - check engine breather system
driving like a girl causes piston rings to not work as well as one's that get exercise
Nice. So I wonder if mine isn't actually misbehaving. Perhaps it just needs 1/2 liter. I guess I could try that before pulling lower oil pan...
Just surprised it's that picky. I would have expected 1 liter low and roughly at the min level on dipstick. By WIS standards, anywhere on the crosshatch does not require adding oil. So...maybe yours is also not right?
Yeah M275 probably uses the M113 oil monitoring system. WAAY different than what M273 uses. It measures oil quality, oil level and oil temp. And it seems to work fine on my E55. Figures that I'm questioning the simple version on this car when the more complicated version on my other car works fine.
Again I think it's just a float-type system. Level OK, level low. That's it. The rest is algorithms that compare the OK or low signal against current conditions to make the final call on whether the level is actually low or not.
I ended up adding a total of 2 quarts over the past few weeks until I got a level I was satisfied with on the dipstick (hot, no O-ring). That's a little disappointing. And the check oil message seemed to go away....but then it came back. I drove the car on a long highway drive to NH and the entire way up, no warning. On the way back, the check oil warning came up four times. Checked oil when we got home and the level was still perfect. So I conclude I do need to do the sensor.
I was reading a little more carefully through WIS and it appears there were two sump designs for the M273. There is a mid-sump with a small, sheet metal style lower oil pan with only 6 bolts. And a larger, deeper pan with WAY more bolts that also has more stuff in the way, as a front sump design. Turns out I have the mid-sump which could be correlated with 4Matic but WIS didn't say how to tell (other than looking). So that's good news I guess.
Now for the dumb question: do engines with the mid-sump pan have a drain plug?? WIS says to extract the oil. I haven't gone back under the car yet to check but I didn't see anything obvious when I was doing the A/C pulley.
Thinking about it more, if the sensor is under the front sump on front sump cars, is the location different for mid-sump cars?? I would hate to pull that mid-sump pan and find nothing. If the sensor is in the same location on all M273s, then it would be under the front cross member?? WIS is unclear on this, as usual.
Looking at EPC it seems to show the sensor is the same part but again the location is in the front. 4Matic cars have a totally different oil pan to accommodate the front axle and I have no clue how removing the small mid-pan on a 4Matic car would grant access to the front of the engine where the sensor is. So either:
A) The sensor is in a different location on 4Matic cars
B) You have to remove the entire oil pan on 4Matic cars to replace this sensor
I can try to locate the harness plug for the sensor as that may give me a clue where I need to get access. If I have the pull the upper oil pan I think this job will never get done because I'm not sure it can be done with the engine in the car (or drop the subframe). This is turning from a simple job into a nightmare really quickly. Hopefully someone can straighten me out....or I'm right....
Never really understood this message. If its low, you'll get "add quart at new refilling". But check what, is it too high or too low? Is it trying to say get a oil change based on interval? Who knows, I checked the dipstick, and it looks fine, last time I got it.
M273 cars have a simple oil float sensor compared to the much more sophisticated oil level sensor on engines like the M113/112. Mine is clearly malfunctioning.
Alright took a closer look. If I am not mistaken the plug is in a totally different place on the 4Matic and is near the 6 bolt lower oil pan cover. I can tell because it is a 2 pin plug with only 1 wire used. I looked at my new sensor and it also has only 1 wire used. So I am feeling good about this again. In the middle of rear brakes at the moment but will get back to this....
Pulled that pan. The sensor is up there but it is very tight. I think I need to pull the oil pickup so I can at least get my hand in there. But I need an O-ring in hand so I will be confident I can get it back together...
Got the two O-rings. Looks like the smaller nitrile one fits. I tried to squeeze the thicker Viton seal in as I know that's a much better O-ring material but it just didn't want to go in and I didn't want to break something.
With the pickup out of the way it was definitely easier to tighten the plug bolt on the oil level sensor. Still annoying as I still had to do it with a closed end wrench (fun fact: a 5/16" works on an E10 head). But I got the sensor back on.
Then I did the pickup. Also easy. Wish the black O-ring fit a little tighter but oh well. The old one was square and starting to get fairly hard (not totally brittle yet). Kind of seems like a service item you should do every 10 years. I know it's a big deal on my E55 and NOT easy to get to on that car.
Also it took a long time to clean off the pan and cover surfaces to prep them for new RTV. Maybe the most annoying part of the job. But I got it done, goobered some stuff on the pan cover, smeared it with a clean glove finger and slapped it on. Torqued to 10 lb-ft in some kind of pattern.
I let it cure for an hour (went on my walk) and during that time it occurred to me that I did not put the drain plug back. That was correct, I had not. Geez. So I put on a new copper washer and put the drain plug back. 25 lb-ft is what I did. Then I attempted to dump 9 quarts of oil in.
I say attempted because this is where I made my patented stupid mistake. I added a full 5 quart jug of M1 0W-40. Then I picked up the other jug and added 4 quarts. Only problem was I grabbed the 5W-30. So now I have to do another oil change but honestly it's not a bad thing because I was working inside the oil pan and despite my attempts to be neat and tidy I am sure I got some crap in there that was on my gloves or something. So I'll do another oil change soon and chalk it up as a flush.
But the good news is everything seems good. No leaks. Once I do the second oil change I'll worry about checking the oil level on the dipstick, hopefully see a perfect oil level, and then I guess hope I don't see the "check oil" message until the oil is actually a quart low or whatever. I think there is an engine VIN break that specifies which to use. I suspect the Viton is for newer ones (begins with 60 I think) and mine is the older one (begins with 30), since I have an 07.
New sensor bolted in
Oil pickup tube
Oil pickup
Oil pickup screen
Identical jugs but different labels. They were next to each other. My bad.
Finally did my second oil change and got 9 quarts of the M1 0W-40 in there. Warmed up fully, checked oil after sitting ~10 minutes. It is halfway between max and min. Is this normal? I expected it to be at max. In every other car with a dipstick, this would require me to add oil but this could be normal. And yes I removed the O-ring to get this reading. With the O-ring installed on the dipstick, the level reads even lower.
So, is this normal or do I need to add another quart which would bring it up to 10 in the sump?
Finally did my second oil change and got 9 quarts of the M1 0W-40 in there. Warmed up fully, checked oil after sitting ~10 minutes. It is halfway between max and min. Is this normal? I expected it to be at max. In every other car with a dipstick, this would require me to add oil but this could be normal. And yes I removed the O-ring to get this reading. With the O-ring installed on the dipstick, the level reads even lower.
So, is this normal or do I need to add another quart which would bring it up to 10 in the sump?
Kev,
I would wait till the car is cold. I usually check the next morning after the oil change. And yes these cars play a little with you when it comes to the oil capacity. That is why the dealer just puts in what the book calls and leave it at that. My car came from a Mercedes dealership and the last oil change was done there. After I came home with it, I checked and it was about 3/4 of a quart over. Had to get a pump and take some out. But back to your question, wait till the car is completely cold and check it then.
But you are supposed to check it hot. Says so right in WIS. So if it is designed to be checked hot, that will be a lower level than cold I assume. But I can do that just for giggles.
But you are supposed to check it hot. Says so right in WIS. So if it is designed to be checked hot, that will be a lower level than cold I assume. But I can do that just for giggles.
Yes you assume correct. I personally always check my cars cold
Yes you assume correct. I personally always check my cars cold
Yes every car I've ever had you would check cold. This is the first you are supposed to check hot. I don't normally park on that level of a surface so I'll figure something out. It would be funny if it was perfectly at max when cold. It probably will be.
It must be done on any car hot just after its been running - the idea isn't to feel good about the level
its to ensure in its normal running state is has the right amount of oil for cooling and lubrication purposes
this is achieved by having the oil at the right temps in the right places around the engine - the reason MOST don't have an issue doing it cold is many cars under NORMAL conditions don't vary by much
Merc says hot within 5 mins of running
Jags used to say within 2 mins of running
the reality with modern oils and engines within 30 seconds is no different to within 4 mins
arguing my case I gave this example
imagine I'm driving across Germany at 140mph and have completed 300 miles, and just used a tank full of fuel. To get that speed and distance I'm working the engine hard at high revs for prolonged periods - perfect conditions to use a bit of oil. Now I stop to refill the fuel tank and have another 300 miles to go. Do you expect me to wait 12 hours to check the oil or would a normal person fill the tank and then dip the oil just a few minutes later?
And thus would ANY manufacturer have considered a design of dip stick reading around an engine measured shortly after it was turned off from hot, or a magic one that anticipates some, partial or no oil drain back from pumps and galleries ?
imagine I'm driving across Germany at 140mph and have completed 300 miles, and just used a tank full of fuel. To get that speed and distance I'm working the engine hard at high revs for prolonged periods - perfect conditions to use a bit of oil. Now I stop to refill the fuel tank and have another 300 miles to go. Do you expect me to wait 12 hours to check the oil or would a normal person fill the tank and then dip the oil just a few minutes later?
I hear you and that's a good engineering rationale. But the reality is, most Japanese and American engine designs don't guzzle oil like that, even under those conditions. So checking cold once a day/week/month/never works just fine. Are we driving cars or aircraft here?
All that said, the point is, I need to know what a normal level is on the dipstick, hot, because I will be taking a 2,500 mile trip in Feb and this car's oil consumption is completely unknown to me. Once I establish that the consumption is quite minimal, I can relax. But until then (considering I also just fixed the sensor) I really want to be able to trust the dipstick. Hence the question.
So I'll ask again: what do people see on their dipstick, hot, after 5 mins, with a KNOWN CORRECT oil quantity? O-ring or no O-ring?
Mine has no O ring, it used to breath a fair bit and once threw the dipstick up the tube.... never done it since.
Dipsticks can be dangerous - you have no idea if you have the right one and if the tube is correctly fitted to the engine - the sensor on mine is perfectly able of informing you when you need to open the bonnet.
If you drain and fill with 8 litres you will be close enough - they have 3 litres more than anyone in USA needs as you drive so slow.
As for a Japanese car its not the make, it the luck of the draw how the machine tools have worn when your engine components where made, the running in style and the type of use. Get a Honda drive like a girl then do 140 across Germany for a tank full it will have used a litre
Alright well here's hoping my car doesn't use excessive amounts of oil between changes (or need any during my long road trip) AND that my sensor is now working properly (considering I just replaced it)...
The O-ring is technically needed so crankcase breather air is metered properly by the MAF. I understand it's a small amount in your case.
And yes I understand my broad generalization about oil consumption had flaws. I'll even agree with you on the Honda case although like you said it totally depends. MANY engines are just tight. In my brake pad thread I mentioned my 05 CTS-V and The Dragon. I think I drove on the order of 5,000 miles between the driving down to NC, hammering around on mountain roads in western NC, and the drive back. My car had ~105k on it and used the famous LS6 which had early issues with oil consumption, if you read the Z06 forums from circa 2001-2002. I drove my car extremely hard at times. Granted a lot was also just getting 25-26 mpg highway but, still, know how much oil it consumed on the ENTIRE road trip?
Zero. Nothing. Not a drop. That car made 400 hp, stock, with pushrods, and revved to 6,500 rpm just like Mercedes V8s other than the M156. I feel like that flies in the face of a lot of Euro designs.
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. It will tell me how much to add, 1 quart, 2 quarts.
