Damian.

The oil consumption is very high, but I would have thought a litre per 1500 km is cheaper than an engine rebuild if it only has to last for five months. A compression test should reveal any fault with the rings and valves if you wanted certainty.

My money is on the themostat. The temperature should remain rock solid at 90 once the engine has warmed up. If the ECU senses a lower temperature it may be over fuelling thus causing at least some of the smoke and the poor performance. I suggest you renew the thermostat before attempting any major work on the engine.

Thermostat is certainly a cheap option to look at. 

I'll try that next and get back to you all. 

 

Well...... Changed the thermostat and the temp gauge has stabilised but it has not improved the smoke situation. Trying to get hold of a compression tester at the moment. 

Also talking to a friend of a friend that has a newer 8P that is statuary write off from a side impact that I might be able to get really really cheap. Not sure yet but I have also been offered a hoist and a spare pair of hands....

I'm glad to hear the minor problem of temperature control has been solved. It's a shame it failed to solve the major problem with oil consumption.

Changing the engine is a big job so it is worth testing cylinder compressions before committing to the work.

If you do need to change the engine be aware that it may also need the donor car's ECU, and also some coding work with VCDS or similar. I am not familiar with the details of the work so wait for advice on this forum from those who do know, or search for professional advice elsewhere. The hoist and another pair of hands will be worth several cases of beer, or even Fosters if that is preferred.

If I go down the path with the other wrecked car, it will be complete. It is still'drivable' apart from the structural damage. Again...if that is the case, I would end up with a car that I would be able to keep as a second car in the longer term. I love driving the A3. More research would need to be done to locate all canbus systems required to move across.

I've put my feelers out for use of a compression tester to check anyway. 

I wouldn't inflict Fosters upon anyone...

Hello Damian,

A compression test may (in caps) indicate which cylinder/s are at fault, but I doubt it will be an accurate enough static test, and I wouldn’t hang my hat on it. 
My feeling is that this car is pre ‘skinny piston rings’ model - this believed to be for the 2009 model year - but I could be wrong. 
Not that it helps you, but our 178K miles 2006 A3 doesn’t use any significant quantity of oil between annual services, based on a now 6K/a usage. 
If you are going to fit the engine from the write-off, I would be renewing the cambelt assembly along with the auxiliary belt before refitting.

Regards,

Gareth. 

Wondering how you are getting on with this Damian-? 
Regards,

Gareth. 

There has been a twist in the story.....

The smoke kind of stopped.

Driving to work and lost a lot of power and wouldn't rev above 4k. Thought it went into a limp mode. Nope....

Talking with a couple of mechanics we may have got to the bottom of this.

Looks like the smoking eventually blocked the cat turning it into an asthmatic. I cut a portal into the side of the cat to inspect and gutted it as it had collapsed. All the power back, but also the smoke. 

The cause of the smoke is the valve stem seals. It has me confused as in my experience that usually makes it smoke on start up, but not so in this case. When in slow traffic or with my foot off the accelerator going down hill, the vacuum sucks the oil past the stem seals making it run a little rough and blow smoke. I changed the seals last week and have driven about 1000 km. No smoke and the oil hasn't gone down noticeably. 

All this nonsense over 60 bucks with of seals. 

I changed them without removing the head after chucking a bore scope down the plug holes to inspect. 

Now I just have to get a new windscreen after I got a monster crack 2 weeks ago. 

Thanks to everyone for help and suggestions. The old girl lives on.

Edited December 12, 2025Dec 12 by damo_4701

Thanks Damian. The only way I can correlate all that is to suppose the worn stem seals allowed excess oil into the crankcase via the rocker box, which was then drawn into the engine and blocked the catalytic converter. What bothers me is why you had no problems with the PCV valve, and no DPF warning light.