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Old 05-27-2008, 02:07 PM   #1
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Default What are the symptoms of a bad or going bad Cam chain tensioner???

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Old 05-27-2008, 03:33 PM   #2
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Default Cam chain makes thrashing noises, inspection reveals slack/free play in chain....

and there may be cam timing error DTCs, or not.
The way cam timing is varied, is be shifting the built in chain slack between the limits of the upper and lower chain paths. Depending on where the designed "slack" in the chain is, in relation to the drive and driven sprockets, determins intake cam timing. The geometry of the chain adjuster and the reletive positions of the components is configured to prevent introducing slackness in the chain beyond the amout by design, used to vary cam timing, controlled by the timing adjuster, and limit chain tension at the zero free slack tension. Wear of the adjuster chain guide shoes and in the chain and sprockets, is how additional slack developes, the position of the cam timing adjuster can't cause chain slack, only cam timing error if not moving to the postition required for a certain PWM duty cycle percentage of the drive voltage from the ECU.
The cam chain timing adjuster does not provide any tensioning forces to accomodate chain and guide wear. It's sole task involves shifting the position of the chain normal slack between the upper and lower paths. The chain guide shoes wear, along with chain and sprocket wear is the cause for sloppy cam chains.
Don't think of the cam timing adjuster as a "tensioner", it doesn't have that function.
Are you experiencing symptoms you think may be cam chain related issues?
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Old 05-28-2008, 05:56 AM   #3
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Default maybe I'm just paranoid, but sometimes at idle I hear whats sounds like a marble rattling in a

plastic container. Its almost like a gurgling sound and I hear it only at idle or if I keep my foot on the brake and slowely release the clutch to bog down the engine. I also get that code that one would get if there gas cap is off after every fill up. I just reset it with Vag. If I do a WOT pull up to 4000-4500 rpm and let of the gas, I hear a significant rattle which is probably my intercooler pipe rattle against the frame rail.

Question: If the CCT has extra slack or is bad, will I be able to hear it the the hood open at idle or is when does the usually occure so I diagnose it?
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Old 05-28-2008, 05:56 AM
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20t, a4, adjusters, audi, bad, cam, camchain, chain, functioning, signs, slack, symptom, symptoms, tensioner, timing

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