Hi all, new here. I have a 1.8T in an '99 A6, with no boost. Have read many of the threads here and elsewhere about it but need a little help if possible.

Symptoms:
Can't hear the turbo at all, and negative pressure on the manifold, under load.
No check engine light or fault codes
The turbo is not seized (I took the pipe from the airbox off and the blades spin easily)

I *guess* the culprit is the diverter valve. I think this is the vacuum operated thing bolted onto the turbo, with a rod going forward to operate a crank mechanism.

The rod is attached to the crank, it's not fallen off.

I can't get the rod to move at all, either way, using pliers. Could it be seized? Can it seize "open" preventing the turbo from working?

And if it's not that, what else could it be?

Thanks for reading, and for any suggestions!

 

Well if its a 1.8t it's not an a6. And if you can easily get to the turbo it's also not an a6. You have an a4(sounds like at least). And also sounds like the waste gate your messing with not the diverter valve. You do realize the turbos on these cars are really small an don't make much noise? How do you know you have negative pressure or no boost at the Mani? Do you have a boost guage? It is possible your waste gate is broke but we need more correct info about your car to help you diagnos than what your giving us

 

Erm, no, it's really an A6!

No, it's an A6, Avant, engine code APU
And I did not say the turbo was easy to get to - I've taken out the air box and loads of pipework to get anywhere near it, and still can't easily reach that valve mechanism, whatever it is. I guess I'll have to take the whole turbo off to get any further.

That's why I asked!


Yes, I'm aware of that. But it's not doing anything.

No boost gauge. I tapped a flexible hose with bulb on the end into the car - under full throttle at 3000 RPM the bulb remains "sucked in" - i.e., negative pressure.

I haven't said anything incorrect as far as I know, just asking for advice. Thanks

 

Looking further I noticed that the valve is pressure operated off the compressor, not vacuum. I connected a bike pump to it and could see it working nicely.

Also took the intake hose off and could see the turbine spinning nicely with the car idling.

But still no boost!

 

Hi i know its a a6 as i own one my self

if the turbo is not boosting there is defantly a leak some where all i can suggest is
1) if you can move the internal wastegate easy with out any resitance then it is nackard
2) if the wastgate is fine then time to look at boost hoses both inlet and outlet housings for cracks or mayb if audi,s have them a the boost controll soliniod i know most turbo cars do but i am new to audi,s hope tht helps :-)

 

or you can sell it and get an a4.