A6 tdi TURBO info

[A6dub]

I have recently purchased a 1.9 tdi (110bhp) A6 . It is a 1998 AFN. I now need a new Turbo. I have been able to source a Garrett VNT15 (028145702H) from a VW Passatt. Can anyone tell me if this is a suitable turbo unit for my machine?? Or can anyone offer any general info??

[ini]

The standard turbo on your 110 is a vnt15.

The Passat vnt15 turbo is identical.

You can also fit the vnt17 from the later 130bhp engines, it will bolt straight on.

Are you sure that you need a new turbo (bearing or impeller damage) as unneccesarily trying to sell people a complete turbo is standard practise for many dealers and garages.

[A6dub]

I'm pretty sure i need a new turbo, I have recently noticed black smoke being expelled from exhaust when accelerating quickly, using high revs. I mentioned this to my mechanic when he was fitting brake pads. He checked it out and verified that there is a 'whistling' sound from the turbo even when just reving the car. I have also noticed this 'whistling' sound when on the motor way when using turbo. He believes that i will need to replace turbo. What do you think, do these symptoms sound consistent with turbo failure?

Are there different types of vnt15 or will any vnt15 fit my car. I've tried to verify the part number on my turbo, but cannot see it wile its still in the car.
Would i be right in saying that it would be preferable to fit a vnt15 rather than a vnt17?

[ini]

There are different types of VNT15, but the Passat uses the same AFN engine and turbo as your Audi, normally the only difference on the 110 TDI's is the ECU.

Given that the Passat is the A6, they are more or less identical.

The only thing to look for is that the engines are mounted in the same way (inline or transverse), as the outlet to the intercooler may be rotated in respect to the manifold.

Fitting a 130bhp vnt17 will not make any real difference to your car, as the boost is regulated dynamically (it requests a certain pressure, and spins up the turbo until it is attained). It will however give a slightly cooler charge, and be able to provide a slightly higher boost if tuned.

The 130bhp VNT17 is just the modern version of the older vnt15, they are internally the same.

A whistling noise is standard for a TDI. I would worry if i stopped hearing it on my 110 afn.

It is possible that you require a new turbo, i just wanted to point out that dealers and garages are very keen to sell complete turbo's.

When they fit the new turbo they may incidentally replace a 10p piece of tubing that was the actual cause of the boost loss etc.

[A6dub]

Well i don't really have any boost loss really at the moment. The only symptom i have at is the fact that a large ammount of black smoke comes form my exhaust when using high revs??

[ini]

Your smoke at high rpm could be caused by a few things.

A restriction in engine breathing on the inlet side (dirty airfilter etc)

Dirty injectors, or a fuel addative (injector cleaner etc)

The injection timing could be slightly off (to far advanced).

You really need to have any fault codes read with vag-com or garage/dealer equipment.

If you are not experiencing limp mode/power loss under load or at higher speeds, your turbo will be producing roughly the requested levels of boost pressure.

[A6dub]

I've now noticed an 'eggy' type smell coming into the car when i have the air turned on. Its especially noticable just as i turn the ignition. Do you think this has anything to do with the symptoms originally outlined or seperate issue??

[ini]

'Eggy' smells are normally associated with unburnt fuel in the CAT (rich mixture/overfueling/underboosting)

or

Overcharging battery (damaged battery or alternator)

or

Bateria/fungus growth in aircon.

[paul b]

If you have no power loss at all, are you sure you need a new turbo? Black smoke does appear from the exhausts of modern day diesels it's just the way they are. It depends how much black smoke you mean. The eggy smell would be something totally different maybe the aircon, I would have thought.

[onzarob]

My 110 AFN smokes and whistles, and i done 12K since I bought it.I don't think you have anything to worry about. My car done 137K in total.

There are certain whistles that are not good, caused by the vanes rubbibg the casing, but really the oinly way to say the turbo is on the way out is have a look, so i would be sceptical unless this has been done.