Hello,
Me and my husband recently bought a used Audi Q7 3.6 Premium. Only has about 90,000 miles. Last person who had it drove the **** out of it... put 3,000+ miles on it within a month. We live in upstate NY where it's been snowing the past couple of days and been about 15 degrees and lower. Noticed a loud *** rattling noise from the around the engine when it starts up, goes away after 5 seconds or so and doesn't do it while we're driving until we start slowing down. We don't think it has anything to do with the cold weather because the car has been in NY for the past 8 years or so. Can't get to our mechanic until Monday. Have yet to find any posts with solutions and haven't really found anyone with an identical issue. Someone recommended we change the oil, add Marvels Mystery Oil and go from there, but that isn't going to give us a solution fast enough. We have a 30 day warranty. If anyone else has experienced the same issue please let me know! Unfortunately you can't post videos.

 

If the MIL is flashing it probably is having misfires. You need to scan with VCDS or similar for trouble codes.

 

As far as we know there’s no codes or warnings popping up. We will for sure get something to check and be safe. We’ve been reading up on possibly dealing with a timing chain issue.

 

The rattling noise for a few seconds at startup is the timing chains, and no, it doesn't necessarily mean that they are fixing to break. IMHO, changing to a better oil can alleviate most of that startup noise, but on an used car you would want to do an oil flush product to remove any built-up varnish and soot deposits from the engine, which can also help your timing chain tensioners to function normally, as part of changing the oil the first time. Also, don't take it for granted the car has the correct oil in it unless you can verify that. Both Q7s I've purchased had the wrong grade of oil installed by the selling dealer as part of their 'free oil change' included with purchase of car, etc., which really doesn't do you any favors if they put in the wrong oil class or weight for your engine type. The only way I found out regards to incorrect oil installed was by asking what they put into the car; in one case I had to go drive to the 3rd party shop that did the oil change to find out, as it wasn't listed on the receipt for the service.

If you do have a 30 day warranty on car, go pay a qualified mechanic to do a purchase inspection on the car for you...a very small price to pay for the inspection, especially if it does need timing chain tensioners replaced, which is a very big, expensive job. This is the best advice you will ever get on an older Q7, bar none. Pay a professional to inspect the car and give you a write-up on the car's health. Best to choose a mechanic that's familiar with German cars, if you've got one nearby, due to familiarity and having the correct tools and scantool to interface with the car's systems.

You do need to scan any used Audi with a VAG (Volkswagen Auto Group)-compatible diagnostic scantool to see what's really going on under the surface of the car, as lots of trouble codes won't fire off a MIL/CEL on the dash display, but they tell you something is wrong and generally point you to what is wrong. If you don't use a VAG-compatible scantool that can actually 'talk' to this car, then you aren't going to see much.

The OBD-Eleven basic is cheap entry point to just read/clear codes on this car, but if you plan on DIY maintenance/service on your Q7, then you will need the VCDS setup, which allows you to actually correct faults in modules, and supports everything you will need to do for this car...it costs=one hour Audi shop labor, which is what you will pay if you ever take it to Audi for any problem.

 

Thank you so much for your response, it’s very helpful. The dealership we bought it from sells only European vehicles and has their own shop to work on the cars they have. Supposedly all together their mechanics have 100+ years of experience. We do plan on redoing the oil and adding some Marvels mystery oil - that is what my dad uses on his and he’s had 2 Q7s for the past 3-5 years or so. We are going to ask for the maintenance history from the dealership because they’ve had the car for 3 years. I have read that the timing chain begins to show problems anywhere from 90,000-120,000 miles so that is why we think it could be that issue. If it is the timing chain we are definitely going to take advantage of the warranty because we’ve literally had the car for 4 days and it’s just so insane that after a week of them having it to do maintenance and check everything they never noticed the issue we’re having. We bought the car on Tuesday and the problem started on Thursday. We bought Castrol Edge 0W-40 and that’s what we plan to use to change the oil.

 

It doesn't really matter what the dealer sells, only how much are they willing to invest in their pre-sale inspection/repair/make-ready process; 30 days warranty isn't much, but it makes a nice selling bullet point on the sales pitch. On our '15, it had a 30 day also, and I got them to pay for Audi OE oil change kit (since their shop put wrong oil in car), new OEM rear brake rotors/pads kit, brake fluid, and a new alternator & serpentine belt...a pretty expensive haul, but I told them what was wrong with it.

Having used both Castrol and Audi/VW branded OE oil in our Q7s, I won't use either of those again since I've switched to Liqui Moly oil, and experienced how it runs much smoother/quieter in our Q7s engines...very impressed by the Liqui Moly. Also a 0W40 oil is a very wide temperature spectrum to cover, and you may want to revisit that choice to better reflect the climate where you are actually using the car. Verify the correct weight/oil spec for your engine, then if need be, adapt to fit your local climate if it falls into the 'extreme' cold/hot temperature ranges. Don't reinvent the wheel on these German cars, and don't make assumptions about fluids based on other types of cars you've had prior. It's all laid out for you. If you keep this car, be sure to do the driveline fluid services; transmission, transfer case, front/rear differentials, etc., as those are not incorporated into AUDI's service intervals. If you don't hear them making noise already when driving it, (try lowering a window a bit) you soon will.

 

Thank you again. We will definitely be sure to do much more research and be sure to invest in better oil.

 

It's odd really; I've been using Castrol oil products in my other vehicles and all types of motorcycles, etc. for decades, and I saw that Audi recommends the Castrol (edge professional) for this car, which seemed very validating, but I found I really don't like it in our Q7s at all...very noisy; almost like there was zero residual lubrication or oil film present at start-up, and in general running. I did an oil flush and swapped the '15 to Audi's OE 'Dealer' oil, and did oil flush / swapped the '10 to Liqui Moly oil in the 5W30 and meeting the VW oil spec. The '15 remained noisy, whereas the '10 is now dead smooth and quiet running now. To keep things even and comparable, as well as try something new, I added the Liqui Moly Ceratec additive to both cars prior to topping them off with the respective oils. Both cars are seeing increased fuel economy consistent with the Ceratec additive reviews, but the '15 with less mileage on the odo remains noisy running the Audi/VW, OE oil, which comes as 0W30 now. I will be changing it over to the Liqui Moly 5W30 oil at next change interval, and never look back; no question about it.

I realize not everyone can run an oil change experiment side-by-side like this in real time, which is why I post this up for your consideration. I buy from FCP Euro and I recommend you shop there too.

 

I see what you’re saying. I just wonder if maybe the shop changed up oils or something for whatever reason, because “supposedly” they’ve never heard this before and it’s never happened while in their possession 🤷🏻‍♀️ not sure how it’s magically happening 2 days after having it. Doesn’t make sense. We are definitely going to take the castrol oil back and get the Liqui Moly and see how that does.

 

Stranger things have happened. Actually, since yours is making noise on deceleratation too, and consistently at that, it may have developed a chain guide/tensioner issue. I'd take it in and get them to validate that and have the dealer take the requisite action to correct it under the warranty. You shouldn't be trying to quell the obvious warning sign while it's under their warranty period...get them to take care of it. When you get the car back, then take stock of and focus on the maintenance of all filters/fluids in car, and especially those that have been neglected by Audi and prior owners.