Audi A6 C6 3.0TFSI

[rayyan171]

Hi,

Will be viewing an Audi A6 at the weekend, is there anything I should be looking for. For what I have read these cars are boringly reliable, but is there any issues I should look at? Anything to find in the history?

Thanks

[annodomini2]

Saloon or Avant?

[rayyan171]

Saloon

[annodomini2]

Outside of the usual stuff

Rear lights play up with earth problems

If it's automatic, check gearbox has been serviced, audi say sealed for life, zf say every 80k.

Heater valves stick (run for 30mins or so and some vents will blow hot, and others cold) valve is about £50, but fiddly to change.

Check the display in the centre of the dash works expensive to fix

Water channels in the engine bay get blocked and leak water into the passenger footwell where there are electronics

Pollen filter changed incorrectly can also cause this.

Front bulbs are a pig to change so check they all work.

Check the rear calipers closely the motors for the electric park brake crack and can fail. Also check the connectors to the motors as they can let water into the cable and fail.

Ensure if the battery has been replaced that it has been coded otherwise can cause all sorts of electrical gremlins.

If it has xenon lights, when the bulbs were last replaced, they should be changed every 3 years, but they are £80 each and take the amplifier with it when they fail, the amplifiers are £400 each. So change the bulbs.

When you go to look at it, ideally take something with vcds to run diagnostic tests on it.

[rayyan171]

Great, thanks for that mate, will definitely help. There's much more uncertainty surrounding the V6 TFSI as there are so few many around, but I have read to believe they are as reliable as can be. I also believe they don't suffer from FSI engine coking, but unsure if they have swirl flaps in the intake similar to BMW's.

[bimjim]

I had one for a couple years, it was on 130k when I sold it and still going strong. The only issue I recall was a leaking radiator, caused by a stone I think.

I averaged just under 30mpg, but that's with very little town or stop/start driving.

[rayyan171]

bimjim said:

I had one for a couple years, it was on 130k when I sold it and still going strong. The only issue I recall was a leaking radiator, caused by a stone I think.

I averaged just under 30mpg, but that's with very little town or stop/start driving.

This one we are planning to purchase will be doing about 2-3K per year, mainly town driving, so fuel costs are not really an issue. What did yours average when doing town driving? We are talking about 10 miles per day.

[bimjim]

It was rarely used for town/local driving, so I'm not sure what the MPG was like there I'm afraid.

It's a great engine though.

[Gio G]

Not really anything helpful to add, however I loved mine, that engine was fantastic. Drove from the UK to Southern Italy, it was a perfect cruiser with power on tap..

G

[Dr G]

20ish around town I imagine; great engines (and as you say, reliability is very good) but 'fuel economy' was never their forte.

Heavy A6 with the tiptronic box even on a run 30MPG would be a push.

[Adrian E]

they do tend to drink some oil between services - the thermostats tend to fail at about 50k miles which is worrying/a design fault that outside the USA you have to cover the cost of yourself. It's a bugger of a job for a simple component, as the supercharger needs to be removed.

[rayyan171]

Regarding the Oil, I read that the FSI engines were the ones that drank a lot of oil, as well as the turbocharged TFSI units, but the supercharged TFSI units don't use much oil. May need to keep a bottle or two in the car then, not an issue.

[Adrian E]

Our 3.0tfsi is in an S5 Sportback and the pre-facelift (before 2012) models with the older supercharger design are known to consume a fair amount of oil, but it depends what goes in it. With ours it's worse with Castrol, and better with Shell oils. If I was servicing outside the dealer network I'd go for Millers nanodrive as I believe that reduces it. Much of the usage is, I believe, down to the emissions control kit.

Oil usage isn't a bad thing on its own - we keep a one litre top up bottle in the boot and wait for the dash display to tell us it needs some. I've also retrofitted a normal dipstick to double check the level so it's not over-filled. The display message says 'add no more than 1 litre' but that doesn't give you much to go on in terms of getting it 'right'

[Dr G]

Do you run a 30 or a 40 oil Adrian? Switching to 40 always helped consumption in the V8s but I've never tried it with a 6.

[Adrian E]

From memory (and I don't have the bottles or service history in front of me) I think the Castrol is a 5w30 and the Shell a 0w30, so a bit bizarre that a thinner oil when cold seems to use less oil - it may be due to the formulation rather than the grade? Haven't gone heavier on the hot side of the spec on the S5, but when I decide not to renew the Audi warranty and get it serviced outside the network I'll probably try the Millers 5w30 and see what it gets through

Car gets an annual service in June and I recently topped up 2/3 litre, which I'm pretty sure is the 2nd top up but may be the only one.

Annoyingly Inchcape now use Shell for bulk oil but only offer Castrol top ups! They used to supply Shell......

[rayyan171]

We did end up buying the car, it was quite good. Great power and easy to drive. However, coolant leaked at a rapid rate a few hours ago, so it'll have to be seen to by RAC. Luckily we were near home. I did do some research and apparently its some coolant flange that goes on a hose, meant to be a relatively simple job, but I could be wrong. Will see what happens tomorrow.

[rayyan171]

Further update.

The car has had more overheating issues, even after being recovered by the RAC to a garage. The car is now at Audi for diagnostics. Does anyone know if the 3.0TFSI had any cooling system issues? The coolant didn't boil off this time but the fan is always on whenever the car is on.

Also the engine temperature is always rising, and having to be cooled.

[Adrian E]

As mentioned above, thermostat can be an issue. Very early cars had issues with water pumps too but would’ve expected it to be changed already if it was affected

Could it be faulty sensors or is the engine actually getting hot?

When thermostat failed on ours early symptoms were a tendency for temps to creep over 90c and fans to run flat out. When it causes high temp warning the header tank was bubbling and top of supercharger was stone cold reflecting the fact it’d failed shut

[rayyan171]

Adrian E said:

As mentioned above, thermostat can be an issue. Very early cars had issues with water pumps too but would’ve expected it to be changed already if it was affected

Could it be faulty sensors or is the engine actually getting hot?

When thermostat failed on ours early symptoms were a tendency for temps to creep over 90c and fans to run flat out. When it causes high temp warning the header tank was bubbling and top of supercharger was stone cold reflecting the fact it’d failed shut

Honestly, your symptoms sound exactly like what is happening on ours. It's on 77k miles and I don't see a receipt for a new thermostat. However it's less of a tendency to creep over 90c, more-so it nears red on the temp gauge for a 2 mile drive. Fans are flat out as well, and coolant boiled off it was so hot. Car is with Audi now so hopefully they'll have the parts in stock and will be able to get it done for tomorrow. It's always something that happens when we buy a car, same thing happened with our now sold XC90.

Thanks for your advice Adrian. It's hard to find advice online for the 3.0 TFSI engine.

[Adrian E]

Did you buy privately or through a dealer? The bill for repair of a failed thermostat at main dealer rates is likely to be pretty chunky! Getting to the thermostat involves removing the supercharger (the 'stat lives on top of the engine). We had Audi warranty so only paid the excess, but from memory it would've been about 10 hours labour to change it. If you're paying the bill I'd consider moving the car to an indy or getting the main dealer to match price an indy for the job, once they've diagnosed.