High oil level

Discussion in 'Engine' started by keith of kent, Apr 26, 2016.

  1. keith of kent

    keith of kent Active Member

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    W212 350 Sport 60k miles.
    Noticed that the oil level is too high on the dipstick (awkward thing to use, how did they design that?)
    Using my oil extraction pump I removed about 1 1/2 litres to get it down to the high mark.
    Wonder whether its been overfilled or is it possible that diesel has got into the sump?
    Most of my journeys are 30/40 miles before another cold start.
    Thinking I might just suck out the lot and refill with fresh, just bought 20 litres of gen Mercedes oil from that place in S Wales for £70 on Ebay. I know that replacing the filter would be ideal and the car gets a full service from my local indy annually about 14K miles, but that's not due for about 6 months

    As an aside, one of my number plate lights has gone intermittent, works if I give it a tap. Car is an estate, how do I get at the bulb, expect the connection needs a bit of WD40
     
    Last edited: Apr 26, 2016
  2. MancMike

    MancMike New Member

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    When/how did you measure it? Engine hot, cold etc?

    A massive overfill is likely to have caused you problems, so if you've no issues, you've either been lucky or it wasn't overfilled.
     
  3. OP
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    keith of kent

    keith of kent Active Member

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    Measured hot but car had stood for 1/2 hour after driving. Assuming the oil has had time to run back into the sump, why would hot/cold make any difference?
     
  4. brucemillar

    brucemillar MB Club Veteran

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    Oil is best checked when hot, with the car standing engine off for about 10 minutes.

    Best checked hot as this how the oil will spend most of it's working life. Cold is only when starting up.

    Not sure your model but the tailgate lights are normally held in place by two philips screws then simply pull down and out. The lens is also the bulb holder. The sprung metal bulb retainers get loose and may need a gentle nip up with a pair of long nose pliers and a scrub with some sand paper.
     
  5. DieselPete

    DieselPete Active Member

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    Does mercedes recomend to check oil when hot? Iv personally never heard of this and as a mechanic have always checked engine oil when cold on a flat service, oil expands when hot so got to be careful if youve taken to much out. Id ask the dealer on there correct way of checking oil level if i was you. Could be a very costly mistake.
     
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  6. streethawk

    streethawk Hardcore MB Enthusiast

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    I've always checked hot as like you say it expands. And iam sure when cold it wouldn't be below min mark if it's at max hot.
     
  7. StMarks

    StMarks Hardcore MB Enthusiast

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    Granted liquids tend to expand when warm DP, but if he has had to remove 1.5 litres to take it down to the max' mark, that sounds a lot more than expansion to me.??
    Over filling can do very serious harm to your engine (fwiw the design of 675cc engine in my motorbike has suffered quite frequently from this).
     
  8. st13phil

    st13phil MB Club Veteran

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    Yes. According to the Owner's manual, the engine should be switched off for approximately five minutes if the engine is at normal operating temperature before the level is checked.

    Alternatively, if the engine is not at normal operating temperature, e.g. if the engine was only started briefly, wait approximately 30 minutes before carrying out the measurement.
     
  9. KeithJG

    KeithJG Hardcore MB Enthusiast

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    My manual the same but 8 mins from standstill with engine off and hot.

    If I dip the oil cold it shows Nothing on the stick and will only get a proper reading after some 5 miles of running.
     
  10. kid-jensen

    kid-jensen Hardcore MB Enthusiast

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    I would wait a month or so before changing the oil, or you won't know if you have a problem.

    Just keep an eye on the level by checking it exactly the same way every couple of days.

    If it's going up, you have a problem alright and an oil change won't fix it!
     
  11. Westfaliaman

    Westfaliaman New Member

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    1.5 litres is quite a lot for an overfill, if the oil has been contaminated by diesel you should drain and refill with fresh oil. I understand this can arise due to faulty injectors, faulty high pressure fuel pump, or due to unburnt diesel as a result of aborted dpf regenerations which is most likely. There seems to be a common problem with modern diesels doing short journeys, resulting in unburnt diesel finding its way into the sump, it seems German manufacturers utilise this system whereby an extra squirt of diesel is introduced into the exhaust to raise dpf temperatures when all criteria are met to do the dpf regeneration. If you google it you'll be amazed how common a problem it is.
    I had similar problem recently and had to siphon off 1 litre. I then decided to do full oil change in case it was diesel contamination, and am doing regular check on oil level in case of reoccurrence. Unfortunately I mainly do short journeys during week so am fearing diesel contamination, as per car handbook I now ensure that car is driven for at least 20 mins at full running temperature on motorway at constant speed every 300 miles to enable proper regen, hindsight is wonderful but I shall be switching to petrol at next car change.
     
  12. DieselPete

    DieselPete Active Member

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    If you think you have contamination of your engine oil you can send a sample of your oil for lab testing for around £40 just google oil sampling. We do this alot in work they can also tell you if anything is breaking down long before it will show signs.
     
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  13. OP
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    keith of kent

    keith of kent Active Member

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    due to unburnt diesel as a result of aborted dpf regenerations which is most likely. There seems to be a common problem with modern diesels doing short journeys, resulting in unburnt diesel finding its way into the sump, it seems German manufacturers utilise this system whereby an extra squirt of diesel is introduced into the exhaust to raise dpf temperatures when all criteria are met to do the dpf regeneration. If you google it you'll be amazed how common a problem it is.
    I had similar problem recently and had to siphon off 1 litre. I then decided to do full oil change in case it was diesel contamination, and am doing regular check on oil level in case of reoccurrence. Unfortunately I mainly do short journeys during week so am fearing diesel contamination, as per car handbook I now ensure that car is driven for at least 20 mins at full running temperature on motorway at constant speed every 300 miles to enable proper regen, hindsight is wonderful but I shall be switching to petrol at next car change.[/QUOTE]


    I think this is the likely cause. Having read various posts on Google I now realise that the reason my engine idles at 800 rather than 600 sometimes when hot is because its trying to do a regen. So the thing to do was not to turn it off and restart!
    Seems a regular motorway blast is needed. What revs do I need to do this at at and for how far? Do I keep the speed/revs steady or give it a few squirts?
    Thinking about giving this a go

    Wynns Diesel Particulate Filter Cle...

    Awaiting my oil to arrive, I will pump it all out and replace with the fresh as it seems that it could well be diesel that has raised the oil level.
    What I don't understand is that my previous car, a 2 litre Peuget 407 diesel (2009) which had a DPF never had this problem. Maybe it was because being a 2 litre rather than the MB 3 litre I drove it a bit harder. My journeys haven't altered.
    PS Apologies for using the "P" word on this forum!
     
  14. Westfaliaman

    Westfaliaman New Member

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    From recollection my manual doesn't mention what revs to do the 20 min run at, but from reading other articles online there seems to be a consensus of opinion that keeping revs over 2000 is preferred.
     
  15. MarkII

    MarkII Hardcore MB Enthusiast

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    Hi Keith,

    Sorry to hear of your oil worries - excess diesel from aborted regeneration of the DPF is a possibility.

    On the face of it your 30/40 mile commute should be enough to initiate a DPF regen but then it rather depends whether that's 30/40 miles of fast motorway use or the same in stop/go traffic.

    Ideally to initiate a regen the engine needs a constant throttle at 1,500 - 2,000+RPM for a reasonable period of time (10 mins or more) but with our road traffic that's often not the case and a modern 3litre diesel will pretty much be ticking over at legal motorway speeds.

    Before you change the oil I would suggest getting the engine up to temp and then doing a motorway run at a quiet time of day (such as late evening) where you can lock the car in a lower gear, to achieve a constant 2,000 rpm and then run at those revs for 10 - 20 mins. Do the return journey in the same way and then let the car return to normal operation for the last 5 miles or so.

    Next change the oil/filter, note your level and once a week for a month try and do a 'DPF run' - then see whether your oil is remaining within normal levels.

    If not, then it's worth looking at the possibility of faulty injector/s and getting a leak-off test done.

    HTH Mark :)
     
    Last edited: Apr 29, 2016
  16. OP
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    keith of kent

    keith of kent Active Member

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    Thanks for all the replies.
    I have pumped the oil out and replaced with the new MB oil making sure it is not above the full mark.
    Also got he Wynns product that I mentioned above, added that to a full tank of Shell V Power (I only use this fuel), then drove it on the motorway for about 30 miles at 70mph in 4th gear.
    In 4 weeks time it'll get a really good clean out as we are driving to Vienna and back.
    We'll see what happens......
     
  17. markjay

    markjay MB Club Veteran

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    After filling-up with fresh oil, the engine should be brought up to working temperature with car on level ground, then switched-off for 5 minutes, and the oil level checked.

    For petrol, it should be a smidgen under the top mark on the dipstick.

    For Diesel, it should be halfway between the top and bottom marks on the dipstick (i.e. 1L short of full capacity).

    Not sure if this is written in any book or manual... but this is how I used do it.
     
  18. StMarks

    StMarks Hardcore MB Enthusiast

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    That's very interesting Markjay, may I ask why please.?

    Fwiw I have always run my vehicles with "just over minimum", on the grounds that they are wet sump & less oil drag should therefore be (in my mind anyway) more efficient.?
     
  19. markjay

    markjay MB Club Veteran

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    Engines normally consume oil, and some have minor leaks / 'sweating'.

    It's OK to run on Min if you check the engine oil level frequently (most people don't).

    Topping-up above the Min is a reasonable comprise to safeguard against engine wear due to gradual oil loss.

    Petrol engines' oil capacity will rarely go up (though petrol or coolant contamination are possible), and even when they do the damage is unlikely to be significant, typically no more than a bad oil leak.

    Diesel engines on the other hand can see the oil level rise due to contamination with Diesel fuel, and the results can be devastating for the engine.

    Additionally, petrol and coolant tend (to some extent) to clear the engine oil through evaporation and the engine breather system, while Diesel fuel cannot be removed from engine oil.

    For this reason it is recommended to leave more margin for unintended oil quantity increase on Diesel engines than on petrol engines.

    But again - this what I do and has been handed down to me by older mechanics I worked with... not sure if it's official or documented.
     
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  20. StMarks

    StMarks Hardcore MB Enthusiast

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    It may well not be documented, but it sounds like well reasoned & sound advice IMHO.
    Thank you for an excellent explanation Markjay. :thumb:



    P.S. Fwiw I do check my oil frequently. However I appreciate that a lot of owners probably expect the service engineers to be responsible for such things, and therefore allowing the greatest margin would be best for professionals.
     
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