I’ve just bought a 2015 Q7 Sport Edition with 90k on the clock, sounds like the timing chain is noisy for the first minute on start up, is it worth replacing it as a preemptive maintenance measure as we are looking at keeping for a long time and any idea on what cost we would be looking at, thanks

 

Which engine do you have?

 

3.0 tdi

 

To do the timing chains / guides / tensioners....the engine & transmission must be removed from the vehicle as these components are at the rear of the engine (stupid design in my opinion). So it's going to be a very expensive job, even with a good independent mechanic, I would estimate between $5,000 and $8,000. I'm sure others will chime in with more accurate information soon....

 

Thread creator is in Great Britain; TDI 3.0L Q7 has got 90k kilometers...about 56k miles on it...shouldn't be having any worries regards to the timing chains, just needs to do oil flush, and get some better oil products in it, IMHO. The main component of synthetic oil that differentiates one brand from the next is the additives package. Advertising aside, the actual 'performance' of the oil is based on the additives blended into it by the manufacturer, and what ratings it achieves in impartial, scientific testing.

I've got two of the same car you have, and both were briefly noisy at startup when we got them, with a bit of clatter from the chains until the oil pressure comes up. Using the flush product, a protective additive good for 30k miles intervals (Ceratec), and the Liqui Moly (LM) oil has made a huge difference in our TDIs overall engine noise levels, the level and/or duration of any noise is reduced at cold start-up, and we see increased fuel economy, as well. My TDIs are both at approx 110k miles.

Level-set the used car you just bought; drop in two cans of the LM TDI oil flush product (read & follow directions carefully), bottom drain it fully, then two cans LM Ceratec (well shaken) and top off with LM oil. One of the best things you can do for your used TDI is clean out the accumulated varnish & crud from engine parts, oil circulation system, and timing chains/tensioners, etc., and that's why you start with the oil flush product and leave it in for the max time allowed to get as much out as possible, then finishing with the extended bottom drain/gravity drain. I can guarantee your TDI will run noticeably quieter than it currently does, and get better economy, as an added benefit, if you do this. The improvements are cumulative, and you notice the noise lessens well before you notice the economy increasing...may take 2-3 tanks of fuel before you start to notice the fuel economy is increasing as a secondary benefit of the Ceratec additive, via reduced friction and pumping losses in the engine.

I'm a skeptic by nature, and I need to see results in the data to be won over by a product. I've seen the results on both of our TDIs in both noise reduction and increased fuel economy, and so I heartily recommend the LM products for TDIs, including their ATF for the transmissions. I was actually a bit disappointed that they don't make a lubricant product suitable for the differentials or transfer case on our '15 TDI, and just the diffs on our '10. Otherwise I'd be running nothing but LM lubricant products in my motors and drivelines.

 

They use miles in the England town, so 90k miles on his rig.

 

I'll hold out he's quoting in kilometers unless/until he posts otherwise.
Pretty much everyone on the planet uses the metric system beside we very 'special' folk here in North America, except when we are doing science, or in the military trying to navigate or blow things up, that is, and then we use the metric system, lol. Even Canada gets a different instrument display where kph is the speed measurement standard...jeesh.

Even if it were 90k miles on it, that's still very low miles on a TDI engine, and a wee rattle on a cold engine at first start is most certainly not abnormal, although it normally goes away pretty quickly. Given that the chain rattle does go away post-start, you begin with the low-lying fruit that impacts the oiling system...it's primarily the lack of lubrication at start-up, and the dynamics of that interaction with the chain tensioners that allows one to hear the rattle at start-up. If it were a constant chain noise,then that'd be worrisome.