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2003 A6 2.5 TDI engine rattle over 2500 rpm

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by eeziweb, Jan 9, 2011.

  1. eeziweb
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    eeziweb New Member

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    I have bought a Jan 2003 A6 2.5 TDI CVT, 105k miles.

    The engine sounds like it has a single cylinder rattle at idle speed when it is cold that almost goes away when warm. But if the revs are increased to about 2500 rpm when warm the rattle returns quite worryingly loud.

    Listening through a screwdriver on the cylinder head all cylinders sound similar. Without the screwdriver from above it seems louder between the V than either side of the engine?. But the rattle is more obvious when listening under the car at the front.

    So I'm guessing it might be bottom end?, or could an old timing belt tensioner make this much noise?. I have a doubt that the timing belt (and therefore tensioners) were changed when due at the 80K service, so could that have caused a problem that makes the rattle?. What is the fault most likely to be for this engine model?

    Also, it has slightly milky coolant, and I was told it might be the oil cooler or a head gasket. The red coolant is slightly milky, and I'm told it has had a flush. Don't know if this has any influence on diagnosing the rattle?, and it might be a ‘red herring'.

    Finally, there is quite a bit more wet soot from the right tailpipe than the left, might this point to a potential answer?. Both pipes exit the same box on left of the car, but I don't know if the cylinder banks have separate exits?.

    Any good steers appreciated, thanks!.
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  2. the jammy one
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    the jammy one Member

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    hmm an easy check to rule out top end woul be to remover covers as i found out i had followers rattling around same engine probly not this as you say but easy check to rule out
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  3. adamss24
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    adamss24 Well-Known Member

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    I would check the timing first, if timing within spec then the rocker covers off and lok for cam wear and missing followers and lifters...
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  4. stimpy
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    stimpy Member

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    If this is the AKE engine code, I would have to say it is camshaft and element wear. When i bought my A6, it had just had all the camshafts and elements belts etc changed. When i enquired as to why, the technician told me it was because of an engine rattle.

    Since them i have discovered the AKE engine is prone to camshaft wear. sometimes to the extent where an element can fall off the camshaft. Personally i would pull off the covers and check the cams.

    Just a point my cams were changed at 85000 miles, so at 105K yours have done well. I'm hoping i am wrong, because it is not a cheap repair. But i will have to say, my A6 does drive perfectly apart from the DMF now wearing out.

    Good luck
    Martin
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  5. adamss24
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    adamss24 Well-Known Member

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    Martin, the camshaft wear on v6 engines is the result of longlife servicing and the audi daft ideea of keeping the oil up to 2 years or 20k + miles ! I have a 190k audi a4 with the AKE engine transplanted and it has NO noticeable wear on the cams...I do change the oil every 6k with Longlife Castrol EDGE 5w30 oil. I had a V6 tdi wich had replacement heads twice in its life gues why- Longlife service intervals again !
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  6. stimpy
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    stimpy Member

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    I had been told that the issue was the service intervals, in fact i have just changed the oil this week. I even had to advise the motor factors that the oil they were supping was the wrong grade, they tried to give me 15w40. In an V6 this is like crude oil, but i still had to question the guy further to check his information. Eventually he checked the castrol website, and what did we see, Castrol recommend 5w30. The guy couldn't understand it "a 2001 car using such a grade of oil"

    just shows, even the manufacturers can get it wrong. Personally i don't believe in longlife servicing. on all of my road cars the oil was changed every 10k, on the A6 it will be done evry 7-8k.
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