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I have a 2018 A4 Premium 45 with 95,000 miles on it. I cannot find anything in the manual about when the timing chain should be changed. I recently brought it to the dealer for routine service and when I was paying/checking out, I asked the service advisor when it should be changed. He told me he's seen it needing to be changed anywhere from 95,000 miles to 125,000 miles with 105,000 miles being the "sweet spot". And of course, he said if you hear your engine sounding like "chirping birds", then it needs to be changed right away. My engine is in good overall condition and sounds normal, but I always like to do services preventatively, before issues arise. When do you folks change your timing chain?
First off, the SM I have does not advise inspection as a routine procedure. The SM says you inspect:
If an elongated camshaft timing chain is suspected based
on complaints (for example noises), the timing chain can be
checked as described in the following.
The inspection that drgertol describes is correct; but. the process for checking is slightly more involved so you would want to reference the service manual for details. The SM does have some interesting guidance - particularly about not replacing the chain. So, inspect if you think you have an issue and replace if you are at or past the critical 7 teeth. The SM says:
– Count the visible piston teeth.
TIP:
The visible teeth are all of the teeth that are located to the right
of the chain tensioner housing -arrow-.
• If six or fewer teeth are visible, the timing chain must not be
replaced.
• If six or fewer teeth are visible and there is an entry in
the DTC memory: adjust the chain length using the Vehicle
Diagnostic Tester, 01 - Chain Length Adaptation Diagnosis
and delete the DTC memory.
• If seven or more teeth are visible: replace the camshaft
timing chain. Refer to ⇒ T3.4 iming Chain, Removing and
Installing”, page 129 .
The number of degrees of angle adaptation on the chain may provide a good indication of timing chain stretch. There is a lot of history for the B8 generation that I believe suggests that 5 deg or less is safe. I don't think there is any received wisdom on a safe adaptation value for the B9. Either the B9s aren't a problem or they have not aged enough.
If you think you might have a chain issue, you could buy VCDS and start checking the adaptation value. If the adaptation angle remains constant you might not have an issue. If the adaptation starts to change, perhaps time to check the tensioner to see where it is at.
07-06-2024, 05:55 AM
When should the timing chain be changed?
