Disassembled and cleaned my VNT15 today

Decided today was going to be the day I pulled the turbo to clean the VNT mechanism. 318,000 miles on the original turbo (previous owner commuted - all freeway, dealer maintained vehicle). I was having overboost/limp problems when I would 'get on it' especially on the freeway. Last week I took off the actuator to feel the VNT lever for stickiness and it felt good other than I could tell it had slop and likely a worn control ring. User 97Caron sent me a good control ring (thanks again!).
Here's the actuator action when I removed the turbo. You can hear the slop in the movement when I wiggle it.
YouTube - Actuator level slop
Here's the turbine side when I pulled it apart.

Control ring side

Turbine housing side.

Vanes before cleaning

Here's my old control ring on top of the replacement one 97Caron sent me.

Control lever on the inside was a little worn too.

Most everything cleaned up well with Gumout spray and a brass brush. I very lightly sanded the vane assy by turning it over on top of 1500 grit sandpaper on a flat cast iron table. Lots of rust removed around the exhaust housing side where the control ring resides.
All clean and back together.

It's all back together. VNT mechanism feel even better and the slop is a lot smaller. In the end I think my problems were more than just the worn control ring but time will tell if I solved my overboost problem. Hopefully I have so I can get a Malone Stage 1

Good luck, After I did the same cleanup on the 02's turbo, my under boost issue was cured

fruitcakesa said:

Good luck, After I did the same cleanup on the 02's turbo, my under boost issue was cured

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Mine is fixed now too! Yay! Before I couldn't accelerate too hard for too long on the freeway without it going into limp mode. Today - no such issues!

Now I'm itching to try out a 'tune'.

If it were me I would have a replacement turbo ready before I got a tune...

Nevada_TDI said:

If it were me I would have a replacement turbo ready before I got a tune...

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Would the ecu dump/send to Malone/upload new maps be affected by an older vs newer turbo?

Or just 'expect parts to break as you're on borrowed time' ?

Will I just be throwing away my $$ on a tune that needs to be re-done?

Mostly I'm looking to get better MPG as it's generally better with a stage 1 Malone so I've read.

I think he's just commenting on the likelihood of a successful rebuild, a valid comment.
However it seems you took a working turbo and mostly cleaned it up, your chance of success is good, you'll know soon enough.
Communicate with whoever tunes the car and you'll get what you need, it's a custom type thing.

I would think that you'd be better off getting new nozzles (and injector work) before getting a tune, if, that is, those injectors/nozzles have the same mileage (318k miles).

Right now allow your turbo work to settle down and see how things are- establish a good baseline before jumping into other changes.

Tune won't matter if you do the turbo now or later. But the added power can make the turbo work harder so makes a sticky turbo show up easier than a stock tune.

Most tune's don't return better MPG so if you're getting it just for that, save your money.

turbovan+tdi said:

Most tune's don't return better MPG so if you're getting it just for that, save your money.

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Thanks - I'm getting 50mpg now and I was reading about the Malone Eco stage and people saying just get the stage 1 - better MPG return and more power to boot. Hoping if I keep my foot out of it MPG's will be better.

UhOh said:

I would think that you'd be better off getting new nozzles (and injector work) before getting a tune, if, that is, those injectors/nozzles have the same mileage (318k miles).

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AFAIK, it's all original. Co-worker I bought it from - the only big things he had done was timing belts every 100K, and a new Luk clutch at 300K.
What's a stock nozzle change/injector matching cost? Also is the nozzle also part of the injector seat or do I have to worry about internal wear, not just nozzle orifice wear?

BobnOH said:

I think he's just commenting on the likelihood of a successful rebuild, a valid comment.

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Knock on wood it's been behaving itself on the freeway. Did quite a few full throttle accelerations the past 2 days on my 100 mile round trip commute - no overboost/limp mode. Definitely would happen before.

Communicate with whoever tunes the car and you'll get what you need, it's a custom type thing.

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Thanks! Sent a note to FixMyVw and they said I could rent a flashzilla from them or ship them my ECU for the load. I guess there's no tweaking after the load while running in the car? The closest 'local' tuner is a few hours away.

I've done a number of turbo cleanings where I've had to completely dismantle and inspect. If the vane plate in the exhaust housing was warped or excessively scored from vane action, the probability of getting normal function again was practically nil past 10k. If there is heavy scoring or warping of the plate shown in pic 3, as oldpoopie (Tdi guru here) has told me, "it's trash" and turbo should be replaced. I've had only two turbos so far with such scoring that I was able to correct. A 2001 bug and 2000 golf.

Great info in this thread fellas! Always happy to see this kind of work rather than just throwing money at parts. Most people aren't willing to dismantle these things, but if it's already broken there's no reason not to play around with it to try to understand your car better.

turbovan+tdi said:

Most tune's don't return better MPG so if you're getting it just for that, save your money.

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VEs typically see 1-3MPG increases actually exclusive to that model though, other motors only really see increases in situations where you would otherwise downshift or from exhaust restriction removals.


If Andrew's renting you a flashzilla then you'll be able to test stock vs tuned and see how the boost behaves, if anything that's better than just logging stock boost values. Plus stage 1 is still pretty mild fueling, but I totally agree it'd be best to make sure it's running well stock first.

Owain@malonetuning said:

Great info in this thread fellas! Always happy to see this kind of work rather than just throwing money at parts. Most people aren't willing to dismantle these things, but if it's already broken there's no reason not to play around with it to try to understand your car better.
VEs typically see 1-3MPG increases actually exclusive to that model though, other motors only really see increases in situations where you would otherwise downshift or from exhaust restriction removals.
If Andrew's renting you a flashzilla then you'll be able to test stock vs tuned and see how the boost behaves, if anything that's better than just logging stock boost values. Plus stage 1 is still pretty mild fueling, but I totally agree it'd be best to make sure it's running well stock first.

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That probably is true on the MPG but don't get a tune just for that, Its the right fun factor that's a better reason.

600 miles later, still working great! My test today was going back and forth to Los Angeles, part of which was a 7% uphill grade at 70-75mph for 2.5 miles, the rest at mostly 80mph.

great update, glad it's all working well!

I also have this problem, I am sure. I am going to approach this just as you have. Thanks for the great information and clear photos you have posted.

Did you replace the Control Lever along with the Control Ring or did you do anything to the worn lever?

ICTDI said:

I also have this problem, I am sure. I am going to approach this just as you have. Thanks for the great information and clear photos you have posted.
Did you replace the Control Lever along with the Control Ring or did you do anything to the worn lever?

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Did not replace the lever - it's welded in place to the shaft. It was worn less than the ring.

Still running great! 9K miles since the cleaning/repair.

Still running well with no limp mode after 20K miles

Nice, good read on the thread as well, good info.

There have been many vnt15 owners that weld up the control ring to help overcome a worn actuator arm, but if you can get a good used one like they did above try that.

03TDICommuter said:

Still running well with no limp mode after 20K miles

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Now up to 30K trouble free miles after cleaning the VNT and replacing the control ring.

I think its great you keep updating!
Id say its safe to assume that any turbo problem at this point is unrelated to your cleaning/new ring.
I am creeping up on 300K, and although cleaning has proven to work well, i think i am going to get a new turbo with my TB kit, strictly because of its age and mileage.

X2 that ALHs regularly see MPG increase with proper tune and nozzles.

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