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W123 230E engine noise = timing chain?

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Peter C1974, Nov 23, 2012.

  1. Peter C1974

    Peter C1974 Senior Member

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    Your Mercedes:
    1985 W123 230E & 1998 W124 E220 & 2014 BMW 420d Coupe & 2000 Porsche Boxster
    I have a 1985 W123 230E Mercedes Benz with the M102 engine, single row timing chain. Mileage is 115k.

    I noticed this morning a grinding / rattling sound coming from the front of the engine. The noise is not particularly loud but I like to solve problems before they get worse.

    The noise is most noticeable with the engine idling at approx 900 rev/min. Reved up to 1,500 rev/min, the noise is still there but is being drowned out by the sound of the engine.

    I put a screwdriver on the water pump and alternator and with my ear at the end of the screwdriver I couldn't hear the noise passing through. I suppose the way to eliminate both is to remove the fan belt and run the engine. I will do this tomorrow. The water pump is relatively new - replaced 3 years ago. Age of alternator unknown.

    With the engine running I removed the oil filler cap. I could not hear the noise inside the engine.

    Any ideas chaps? Chain tensioner? Timing chain? I don't know the history of either.

    Anything else I can do check? I have changed the oil regularly and the engine runs just fine.
     
  2. grober

    grober Senior Member

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    At 115,000 MILES a single timing chain and its associated tensioner and guides is well past its sell by date if it hasn't been renewed they are reckoned to be good for about 70,000 miles . With the Engine off!! put on pair of disposable gloves- remove the filler cap and feel the chain with your fingers for any play.
    and check the large crankshaft pulley is on tight when you take off the fan/polyv belt
     
  3. OP
    Peter C1974

    Peter C1974 Senior Member

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    Graeme,

    Thank you for that.

    Should there be any play at all in the chain?

    This is a photo of my cylinder head with the cam cover removed. There isn't much access to the timing chain with the cover on.

    How do I check for chain wear with the cover on?

    [​IMG]
     
  4. grober

    grober Senior Member

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    The "through the oil filler cap " method is pretty rough and ready, but you are looking for any sensation of " slack" in the chain-- is it "firmly seated " on the sprocket- can you move it back and fore can you "lift" it off the sprocket slightly ? Best way obviously is to compare it with a good chain setup you know is sound on another car. this shows how to replace a timing chain in situ [ refers to a twin chain on a V8] but principles the same. Doesn't of course address any sprocket , tensioner or guide wear. http://www.peachparts.com/Wikka/M117TimingChain
     
  5. OP
    Peter C1974

    Peter C1974 Senior Member

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    Update.

    I went back to the car at lunchtime to check the engine oil level - something I didn't think about this morning. Whilst the level is a little lower than it should be, it was above the MIN mark.

    I started up the car and the noise wasn't there. I let the engine warm up to running temperature and there was no sign of the noise.

    I will keep an eye (ear?) on the problem but I now doubt that the timing chain is at fault.

    I will update this post if I find out more.

    Peter C
     
  6. star

    star Forum Supporter Authorised Forum Supporter

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    Possibly a sticking chain tensioner or blocked oil filter.
     
  7. OP
    Peter C1974

    Peter C1974 Senior Member

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    The former has sprung to mind. Can it be replaced easily?
     
  8. star

    star Forum Supporter Authorised Forum Supporter

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    Yes, you just need to pivot the alternator by removing top bolt and the tensioner is to the side of it. Oil filters can block if poor quality oil is used, I've seen the block in 3-4000 miles, easy to check.
     
  9. OP
    Peter C1974

    Peter C1974 Senior Member

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    News update!

    On route home the noise came back. This time the problem is obvious - the water pump bearing has had it. The reason why the water pump failed so soon is because I've glued the (failed) fan coupling together.

    Time for a new water pump!
     
  10. kth286

    kth286 Senior Member

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    not understanding that.

    why the connection between fan and pump ?
     
  11. OP
    Peter C1974

    Peter C1974 Senior Member

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    When the fan coupling failed I chemically welded the fan coupling together, which means that the fan was constantly rotating at engine speed. Normally the coupling wouldn't allow the fan to spin at higher engine speeds, the pump bearing wouldn't like it. So, after 25k miles the pump bearing gave up. Simple really!
     
  12. richardds

    richardds New Member

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    It's crazy that I would find a thread this recent related to my problem. Peter C1974, this is the exact same issue that has happened to me today. Just signed up to say thanks for the diagnosis.
     
  13. richardds

    richardds New Member

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    I was in a drive through this morning when I pulled up beside a wall and noticed this metal clicking right from the engine bay that would increase with the revs. Sounds exactly like you described. I popped the hood and revved the engine with the lever thing in the bay (sorry I'm not mechanically inclined at all) and the clicking was right at the front of the engine around the middle where someone said that's the water pump is. Google'd w123 water pump sound and found this. Amazing. Does anyone know if getting a water pump replaced in these cars is very labour intensive?
     
  14. silverw140

    silverw140 Senior Member

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    do remember the M102 engine is totally different to the 300d engine in your w123 so dont assume you have the same problem.
     
  15. richardds

    richardds New Member

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    NOOOO. Google has led me astray. It's a good starting point at least.
     
  16. OP
    Peter C1974

    Peter C1974 Senior Member

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    Not sure where the water pump is on a 300D but replacing the pump on a M102 230E is quite easy. Actually, it would be easy if the pump pulley bolts weren't seized!

    Also, getting hold of a new pump nowadays is not as easy as it was three years ago. Mercedes do one for £248 exchange whilst ECP can get one for a quarter of the price but they need to order one especially, which takes 2-3 days.

    Good luck getting yours sorted!
     

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