Any tips for removing VNT actuator in situ?

[Froggy_130]

Hi All,

Fitted a new (well re-conned) turbo couple of weeks ago that I was assured had the VNT actuator set correctly. Unfortunately wasn't the case:(

The actuator has been painted and has threadlock applied so I think its going to be a case of removing it and cleaning up and adjusting off the turbo.

Any tips for removing the circlip? Looks an absolute pain to get to!!!! What needs to come off? I'd imagine at least air filter housing and some of the intake piping... Best to do from above or below?

Many thanks in advance for any advice!

Cheers,
Dave

Oops forgot to mention - car is a 2001 Passat, AVF engine :Blush:

[martin1810]

Silly question but how do you know vnt isn't set correctly. This isn't something that you would normally adjust.

[Froggy_130]

Hi Martin , thanks for the reply! Actuator isn't starting to move until over 10Hg applied, and is still moving at over 20Hg...totally different to original turbo, and nothing like I have read they should be set to! Mpgs are poor, and can quite easily cause overboost/limp mode in 3Rd and 4th...

pretty sure it is not set correctly :-)

Cheers, Dave

[Teflon]

I did a lot of research before I split my Audi turbo - there was a lot of info saying not to adjust the actuator else you get exactly your symptoms, or worse. A new or properly reconditioned turbo is supposed to have the actuator set up on an air flow rig so that the operating range and turbo outputs are correct for the turbo spec. and therefore, the vehicle.

It might be worth checking with your supplier whether they do this. And of course there is the obvious question, did they give you the correct one?

[Froggy_130]

Many thanks Teflon - so I think what you are saying is that the actuator could be set correctly, but for a different car! Will check with the supplier.

I believe correct actuator operation should be starting to move with 2-5Hg vacuum applied, and fully open by 18Hg. I've got a technical bulletin document from VW that describes how to calibrate it correctly - hopefully once set correctly it should resolve my problems.

[Teflon]

I learnt a lot by looking at a thread on TDIClub.com. I think it was under "TDI 101" but just do a search for VNT turbo and you will find it.

There's lots of diagnostic stuff and explanations, measuring blocks to check and other stuff. The thread was a bit messy, long and took quite a while to read. It will now be even longer, but there may be something there to help you.

Looking again at your post, it seems that the actuator is needing more vacuum to move it than you are saying it is supposed to need. This wouldn't be an adjustment problem, because there is no resistance at the other end (or at least threre shouldn't be!). Maybe it isn't the correct actuator for the turbo/engine combination?

I also suggest you check both ends with the actuator disconnected from the turbo. At the turbo end, the little lever should move completely freely across its range with a satisfying clonk at both its limits. If not, your turbo is gummed up, not reconned. Before reconnecting, try the actuator with a good vacuum gauge. It should work within its range at the specified pressures. If not, you either have the wrong one or it is duff.

[martin1810]

Hi All,

Fitted a new (well re-conned) turbo couple of weeks ago that I was assured had the VNT actuator set correctly. Unfortunately wasn't the case:(

The actuator has been painted and has threadlock applied so I think its going to be a case of removing it and cleaning up and adjusting off the turbo.

Any tips for removing the circlip? Looks an absolute pain to get to!!!! What needs to come off? I'd imagine at least air filter housing and some of the intake piping... Best to do from above or below?

Many thanks in advance for any advice!

Cheers,
Dave

Oops forgot to mention - car is a 2001 Passat, AVF engine :Blush:

I am not sure I follow what you are saying.
When you start the engine the actuator should move the turbo vanes to the maximum position. This normally allows about 80-85% of the maximum possible boost.
As the engine revs rise the actuator should be moving the vanes back to reduce the maximum possible boost.
That's how it stops, overboosting.
Why don't you get a few VCDS boost logs done. Then you will know what the boost is doing.