This is a new to me 2015 Q7 with 75K miles on the clock. It's been way too cold here to spend any time poking around the engine bay, so I haven't been able to get in there and give it a good looking over. I've scanned for codes and nothing engine related came up. I've noticed some minor chain rattle on a couple cold starts, but most of the time the cold start seems fine. When I first picked up the car, the engine was super quiet. This video is from the other day when it sounded louder than usual. There's a high pitched rattle sound coming from near the back chain cover. You can hear this around the 13 second mark in the video. Also, does that knocking sound at near the front passenger side at the 4 second mark sound normal? Any opinions on this would be appreciated.

https://photos.app.goo.gl/PxZMaXCSyDYmASpQ8

 

No, it doesn't 'sound normal', but you forgot to mention exactly how cold it is when you shot this video, or that the car is left outside or if it's garaged, etc., etc. Details matter.

Cold-cold weather causes all sorts of cold-start oddness to occur, especially when the car is left outside and the oil in the car is perhaps not well suited for your current Winter temps. That alone is gonna cause an initial lack of lubrication to the timing chain tensioner(s) and other hydraulically actuated components you are hearing, and there could be other things going on as well, etc.

Don't make any assumptions the car is prepped for the extreme cold weather you are having, unless you have records that prove it is. I do a complete maintenance reset (fluids, filters, driveline, etc. when I buy a used car. Hoping you had a full PPI done before purchasing it.

Two tips:
You want to change the oil on the severe use schedule...@ 6500 miles or less to prevent known issues from occurring on that engine. Forget what Audi recommends, as that'll just kill your engine. It'd be a very good idea to use an oil flush product like Liqui Moly or similar when you change the oil...purge those old deposits/varnish/gunk from the too-long Audi service intervals being followed.

Audi also removed the entire undercar driveline from the maintenance schedule, claiming them as sealed, non-serviceable components, and having a factory "lifetime lubricants" fill...yeah, sure, and I've got some magic beans to sell you too. Change ALL the driveline lubricants ASAP...your already overdue on Front/Rear Diffs, Transfer Case, Transmission fluid/filter. None of those driveline items are sealed, they all have Fill/Drain bolts, and transmission has a drain opening on pan, but it'll need the pan dropped to replace the filter and get approx 3/4 of the old ATF fluid out of it. The hydraulic/power steering fluid is normally not serviced either by Audi, but they do replace coolant and brake fluid on a schedule, which seem very odd.

 

No it does not sound normal. Do you know if the High Pressure fuel pump and cam follower recently replaced?

 

Excuse me, but what in a world would an hpfp do with the engine sound?

 

@'10Q7TDI_Prestige' Appreciate the tips. I've owned a lot of VW's & Audi's and always do oil service at 5K mile intervals. This is the first 3.0T I've owned and am getting acquainted with it. This video was not a cold start. I don't recall whether it was at full operating temp, but it was definitely warm. My plan is to change the oil and note any differences in what I'm hearing. I was hoping anyone with more knowledge of this platform than I have might recognize what they were hearing and point me in a direction for things to look into.

@mindfulwake Can you elaborate on what doesn't sound normal to you? Are cam followers a known issue with this gen 3.0T? I'm familiar with follower issues on the early 2.0T FSI. I had a MKV GTI and had to detach the HPFP and replace the follower every10K miles to keep it from imploding.

 

I asked about the cam follower because you said there is a ticking noise in front on the passenger side which it sounds like in the video but obviously a video is harder to tell from. I too have a 2015 and have just discovered that Audi is telling people the wrong part number for our vehicle for the cam follower. I am the original owner of my vehicle and before it broke down all repairs had been only by our local Audi. When I replaced the HPFP when it broke down I decided to replace the cam follower as well since there was a slight movement in the roller. When the part looked different I called multiple Audi's to confirm the part number and they said the new one was correct so I installed it. The vehicle is making all sorts of noise now but one is a ticking in the front. I had my local Audi pull the records to confirm the cam follower had never been replaced before and I also saw that the new part is not a replacement for the one that was in my vehicle originally. I have a call into Audi to investigate it. They say the part number should be 07L109311 but the part that came out is 06L109311.

 

According to ECS, the part number starting with 06 is for the 4M generation, not 4L.

 

OK, so the noises in the video take on a bit more urgency given the context that the car was already 'warm' or at running temp when you shot that video. If it is steady making those noises with engine warm, then there's at least one issue.

From the video, I can't really discern whether the noise at left front is from the serpentine belt/idler pulleys, etc., or if that dominant sound is just really loud injector 'ticking' (injector's dirty/clogged and/or failed injector seal possibly given what I'm hearing). Definitely need to inspect the belts/idlers visually for signs of wear/bearing play in idlers, and know that Audi likes to drill relief ports in the block for each injector, so if/when the injectors seal fails, it doesn't kill the expensive injector, and also provides you a clue due to the sound it makes (hissing) when leaking, and raw exhaust smell/discoloration around the relief port, etc.

The 5k mile oil change intervals you like to do are a very good plan with the 3.0T engine. You really want to do a complete maintenance reset, IMHO. whenever buying a used car, but especially one of these Audis. Generally, the brake fluid (2yrs) and coolant (5yrs) are getting changed frequently enough, but absolutely nothing else is/was, so the lower odometer mileage on car aside...hit the reset button, and be sure to use an effective oil flush for the quantity of oil in crankcase, which is a lot.

FWIW: Both the Q7s we bought had been given a fresh, 'courtesy' oil change by selling dealer as part of their prep (Not an Audi dealer), and both were found by me to have used the wrong motor oil weight and/or spec, when I asked to verify what they actually put in the car. Point being to not just take it for granted that everything is hunky-dory just because the car starts/drives off the lot fine.

You've got some diagnosis/inspection work to do, and here's a link outlining the known issues with 4L Q7 chassis, as well as with specific engines...pretty much everything you need to know about really. This format is written, but he also has a video version of this posted to Youtube:

https://differentcarreview.com/2019/...-4l-2005-2015/