Blue smoke

[Audihi]

Hi , I recently purchased my first Audi. There seems to be a couple of issues with it. Maybe someone has experienced the same issues as me and hopefully can help.

Issues are-

Poor mpg 35-40 ( note 20 inch alloys don't help)

When car is warm and when I slow down to a stop and take off there seems to be a puff of blue smoke.

Car seems to keep revs up a little so.egimes when drawing down.

Fan stays on for a good while when I stop after a journey. Even came on after driving 2 miles before.

Auto stop isn't always available.

Car drives fine with loads of power. Haven't noticed any major loss of oil.

[Stevey Y]

Hi I am assuming its a petrol model, the blue smoke could be valve seal wear, but the fan staying on sounds like a dodgy temperature sensor.

Steve.

[SuffolkBoi]

Auto stop/start wont' always work. It's subject to so many parameters that have to be right before it will kick in, the main one being that there has to be enough charge in the battery for it to restart the car.

As above assume you have a petrol version? I have 20" wheels on mine and get 55mpg on a long run (diesel) and low to mid 40s around town.

[Audihi]

Thanks for replies. 

Its a 2.0 TDi 177 bhp Diesal. Noticed the blue smoke isn't always there.    I'm thinking the blue smoke is from regeneration but it seems to do it alot. 

There is no way I can get anywhere near 40 mpg driving around town. Haven't got out on the motorway yet I reckon I should scrape the 50.

[Magnet]

Hello Brian,

As Steve says, blue smoke is indicative of engine oil being burnt, and would not be the colour of exhaust gasses you would expect from ‘regeneration’. 
If this were mine, I would take the car on a 10 mile run to ensure the engine oil is up to operating temperature, then get an assistant to follow you and observe the incidences of blue smoke emission. 
It would be expected that if it was due to valve guide/seals were that the blue smoke would be evident on moving away from being stationary at idle at traffic lights etc. If the blue smoke occurs on general acceleration, then that would indicate issues with bore/piston wear. 
Does the car burn any oil? 
Kind regards,

Gareth. 

[Stevey Y]

11 hours ago, Audihi said:

Thanks for replies. 

Its a 2.0 TDi 177 bhp Diesal. Noticed the blue smoke isn't always there.    I'm thinking the blue smoke is from regeneration but it seems to do it alot. 

There is no way I can get anywhere near 40 mpg driving around town. Haven't got out on the motorway yet I reckon I should scrape the 50.

Hi my Diesel is used as a taxi and I have been running round town a lot during the lockdown and even I noticed the drop in MPG to around 28-30 mpg, it is an unfortunate facet of the Diesel cars design that you have to take them on a long run every so often to give them a good clear out, with the restrictions lifting I had a good run out to Colchester the other day approx thirty two miles each way, when I refuelled at my local Shell on the way back the expected milage from full was 680 rather than 540 running around town and the car was a lot more responsive it just goes to show it works. town driving is always heavy on the A6 Diesels as the power band starts at 1500 rpm the other thing I have found is that brake wear is accelerated because of all the stop start as well as regeneration of the DPF is more frequent, as Gareth suggested keep an eye on the oil level as this would if dropping indicate engine wear as DPF activity is normally white smoke, try taking it out for a run of at least twenty five miles and see what happens, only other suggestion is steer clear of supermarket fuel as its cheap for a reason.

Regards Steve.

[SuffolkBoi]

I should add that I have the Ultra version of the 2.0 TDI which may explain my mpg.

But I echo the above. Whatever version you have, it will need a good blast along a dual carriageway for a good few miles.

Maybe an additive will help too? I've not long had my A6 but I'm using Redex DPF cleaner every third tank to help things along as I do a good few town miles too.

[Stevey Y]

2 hours ago, SuffolkBoi said:

I should add that I have the Ultra version of the 2.0 TDI which may explain my mpg.

But I echo the above. Whatever version you have, it will need a good blast along a dual carriageway for a good few miles.

Maybe an additive will help too? I've not long had my A6 but I'm using Redex DPF cleaner every third tank to help things along as I do a good few town miles too.

Hi if you want a better additive that really makes a difference have a look at the Hydra Maximus additive it works for me, Redex will screw your fuel filter in record time.

Steve.

[SuffolkBoi]

1 minute ago, Stevey Y said:

Hi if you want a better additive that really makes a difference have a look at the Hydra Maximus additive it works for me, Redex will screw your fuel filter in record time.

Steve.

Hi Steve,

 

I was looking at the Hydra DPF cleaner earlier on funnily enough. Is it good stuff?

[Stevey Y]

Just now, SuffolkBoi said:

Hi Steve,

 

I was looking at the Hydra DPF cleaner earlier on funnily enough. Is it good stuff?

Anything they make is good, the Maximus is about the best all rounder I have been using their products for a few years I started just using the standard cetane booster which is good and moved over to the products like the Maximus, it must work as a couple of times I had to have injector seals replaced on my last Mondeo and the first time my mechanic did it he looked really fed up as he explained with 170k on the clock the carbon build up was probably terminal and he said he often had to take the head off and drill the injector out, I gave the offending injector a little twist and out it popped even he was amazed and after that quite looked forward to replacing the seal on the next injector, as he said to me he had never seen injectors that clean on a direct injection diesel unit, the last seal was replaced at 270k, the additive and good fuel definitely work.

Steve.

[SuffolkBoi]

I shall pick up some of the Hydra DPF cleaner then. Thanks for the recommendation.

[Audihi]

Ok going by your comments, I'm thinking its the valve seals. Big enough job I'm sure. Got another puff of smoke after driving downhill for a bit today. Classic sign of the seals gone I think. Will look into the dpf cleaner also. 

[Magnet]

Hello Brian, 

‘Got another puff of blue smoke after driving down hill...’ doesn’t convince me - by your description, that you have valve stem seal wear. 
Have you really carried out the procedure I outlined - with a following observer? 
You might (in caps) be correct in your diagnosis, but would I really want to go tearing an engine apart based on your latest description?? 
Kind regards, 

Gareth. 

[Audihi]

Hi Gareth, no not yet. 

Talking to a guy today and he said its unusual for them to wear on a 12 car. Possibly to much pressure building up and forcing oil past the pistons maybe. Getting it checked out hopefully  next week and will have some answers. 

[Magnet]

Hello Brian,

Just an opinion - if you are going to allow this car to be pulled apart based on anything other than the described logical road test then I think you are letting yourself in for an ‘investigative’ bill. 
It would be great to know how you get on with this.

Kind regards,

Gareth. 

[Stevey Y]

On 4/23/2021 at 8:22 PM, Audihi said:

Hi Gareth, no not yet. 

Talking to a guy today and he said its unusual for them to wear on a 12 car. Possibly to much pressure building up and forcing oil past the pistons maybe. Getting it checked out hopefully  next week and will have some answers. 

Hi thinking about what your friend said, it could well be a blocked or collapsed crankcase breather valve which would cause the sump to pressurise and blow oil past the rings.

Steve.