VNT Repair Procedure

Just be very careful when installing the replacement - especially with regard to the length of the VNT rod... if you set it wrong and get consistent over-boost, you can blow up your turbo...

Please look up how to set the stop points...

Yuri.

Have a problem that just may be a sticky turbo, would like your opinions. I get surges all the time and very poor power over 2200 rpms. I have a boost guage and the turbo does boost to 18+ psi in first gear. After reaching max boost it falls on its face and will go all the way down to 5-6 psi. It does not like going over 65 mph in 5th. I have done the following;
changed the MAF, changed the vacuum lines, changed the N75, cleaned the intake and egr, changed the fuel filter and vacuumed the IP to get rid of all bubbles, changed the battery (it just went bad, nothing to do with this), the actuator on the turbo moves freely and holds vacuum.
What else could it be, any suggestions would be greatly appreciated. I feel the only thing left to do is pull the turbo and clean it.

Stupid question...when putting everything back together, should you put some RTV silicone on all the gaskets? If so, on which side of the gasket, or both?

If you can get full range of motion from the actuator, I am not to sure if taking your turbo off and cleaning it will have much of an impact. At what pressure does the actuator move (I assume you are using a hand pump)?

Richard55 said:

Have a problem that just may be a sticky turbo, would like your opinions. I get surges all the time and very poor power over 2200 rpms. I have a boost guage and the turbo does boost to 18+ psi in first gear. After reaching max boost it falls on its face and will go all the way down to 5-6 psi. It does not like going over 65 mph in 5th. I have done the following;
changed the MAF, changed the vacuum lines, changed the N75, cleaned the intake and egr, changed the fuel filter and vacuumed the IP to get rid of all bubbles, changed the battery (it just went bad, nothing to do with this), the actuator on the turbo moves freely and holds vacuum.
What else could it be, any suggestions would be greatly appreciated. I feel the only thing left to do is pull the turbo and clean it.

Click to expand...

Before I take action (and it seems to me that I need to !), may I just confirm that my turbo is ill.

I have an Audi A4, AFN Engine, 110bhp. 96000 miles done. Since I have owned it, from 55000 miles, I have had intermittent loss of turbo (limp mode), usually when doing 60mph + and accelarating. I seemed to fix the problem a couple of times by cleaning the MAP sensor inside the ECU, as it was getting clogged up with oil from the air inlet hose (causing fault code 00575).

Just recently, I have had almost constant problems with getting above about 60mph in 5th. I stripped the ECU again, this time I found a small quantity of oil had actually leaked onto the PCB ! I gave it a good cleanup, washed out the MAP sensor and hoses with IPA, and took the car for a spin. No improvement. Did a bit of internet "homework", and reminded myself of possible issues with my car. I thought I may be having N75 valve or MAF sensor problems, but after checking the travel on my VNT actuator, I think I may have spotted the problem. With a pair of thin pliers, I am trying to move the actuator arm, and it only travels about 5 - 10 mm. It sounds a bit rough when I do move it. I have taken the hose off the N75 have and applied vacuum with my mouth. Again, the arm moves, but not very far. How far should it move, and is the return spring supposed to be quite strong ? Seems like my turbo needs to be stripped and cleaned, although I am wondering if it could be the actuator itself.

I do give my car "some stick" (4500 rpm+) fairly regularly, as I know that these engines don`t like to crawl around for too long, so I am a little suprised that I have this problem. Having said that, a fair bit of my driving is around town, and at fairly low revs. Any advice/reasurance would be welcome.

ymz said:

Please look up how to set the stop points...
Yuri.

Click to expand...

Anybody have a link on this? And, any chance having the VNT stop points set wrong could cause the EGR weep?

GOlf gt tdi, SLOW SLOW SLOW

Hi guys this thread is massive!
I have been following all of the procedures for slow performance with my gttdi1.9 golf, i have done everything that Richard55 has done(turbo clean ,EGR clean) and it still strugles to go over 65MPH>>it takes about 17seconds to get from 0-60..

What else could it be?
If the exhaust was clogged could this affect top end speed? i am just not sure..oh, it has 144000miles with a new timing belt this week!

Oil line???

Do we really need to replace the oil line? can we clean it out? or does it need to be new to seal properly?

AWESOME, HELPFUL THREAD!!!
THANKS!

Fabian said:

Do we really need to replace the oil line? can we clean it out? or does it need to be new to seal properly?

Click to expand...

Usually it breaks while being removed...

cha$e said:

any chance having the VNT stop points set wrong could cause the EGR weep?

Click to expand...

No... the rod is adjusted so that 3 - 5 in. Hg (using a MityVac or equivalent) causes the VNT rod to start moving...

Yuri.

Do you need to remove the entire intake, egr, egr cooler, and ex manifold along with the turbo like in the pictures or can you take just the turbo off?

Fabian said:

Do we really need to replace the oil line? can we clean it out? or does it need to be new to seal properly?
AWESOME, HELPFUL THREAD!!!
THANKS!

Click to expand...

I bought a new one when i changed out my turbo just to have if mine ended up twisting off. I installed the new one just b/c i had it. I've been told the oil line can get bunged up by using crappy oil but I ran a swab through the whole line and flushed it with brake cleaner without any crap coming out.
I think the key to getting the old one off without having the nut seized to the line and twisting it off is to soak the top of it for a couple of days with a "good penetrating fluid" then when it comes time to loosen the nut heat that bugger up with a good torch. I used the yellow bottle of gas instead of the blue bottles, i think the yellow burns way hotter. That way you can heat the nut fast and not transfer heat all over the place.
The new line does come with new copper crush washers but you can find those anywhere

CTD&TDI said:

Do you need to remove the entire intake, egr, egr cooler, and ex manifold along with the turbo like in the pictures or can you take just the turbo off?

Click to expand...

no, you can remove just the turbo/manifold from underneith if you have a lift or like working on your back.


i usually pull both and clean the intake while the turbo is off, but if it has been done recently or is not carboned up, i just pull the turbo out the bottom. you will need to pull the RF axle shaft though, but it is not a problem.

what is the easiest way to change the actuator?

under the car, quick and easy to do. two nuts, one hose clamp, and one clip. adjust, rinse and repeat.

serve at room temp.

even with my big 6'2'' 250lb clumsy body??

i am 6'3, 275.....

lol...ok...

I just dismantled the VNT just by following the Drivbiwire's instructions.
Excellent source, thank you!

My questions is:

What are the torque specs for the intake manifold bolts, the downpipe bolts, as well as the turbo oil line outlet bolts?

I've yet to find them in my Bentley as far as the TDI. Bentley did list the VR6 exhaust manifold bolts at 25nm, the Downpipe at 40nm. Again they are all for the VR6 engine.

Chapter 21-11
Turbo oil return line Part #17 11ft-lbs
Intake Manifold bolt Part # 5 18ft-lbs
Down pipe to Turbo " " " "

Thanks edjet!

Hi....am battling a P1556 error on my 02 Golf GLS TDI, 185,000kms....new to me car.....

The VNT actuator, which I find quite hard to reach (and cannot really see it) seems VERY hard to push down the rod....With a lot of pressure on it, to the point of hurting my thumb, I can barely manage to make it move 1/4"-1/2",down and then it squeakily springs back.
Root of my problem ? (no power on hills, highway speed)


Admittedly I skipped over most of the replies in this thread, as I am fresh out of the garage and wanted to get the info down before bedtime...(hard day, eh)

Will go back and reread....

get a mityvac ($30 bux) and pull the vac line of the n75 that leads to the actuator. Try and pump it up to 25" hg. If you cant, it could be bad. 100 bux at tdiparts.com and a pain to change. lol. if its fine, there are MANY threads that will point you in the right direction....get ahold of someone with a vagcom...that will help

ve9aa said:

Hi....am battling a P1556 error on my 02 Golf GLS TDI, 185,000kms....new to me car.....

The VNT actuator, which I find quite hard to reach (and cannot really see it) seems VERY hard to push down the rod....With a lot of pressure on it, to the point of hurting my thumb, I can barely manage to make it move 1/4"-1/2",down and then it squeakily springs back.
Root of my problem ? (no power on hills, highway speed)


Admittedly I skipped over most of the replies in this thread, as I am fresh out of the garage and wanted to get the info down before bedtime...(hard day, eh)

Will go back and reread....

Click to expand...

Once you apply vaccum with the MityVac, the actuator should start moving at about 3 or 4 hg. If it starts moving, lets say at 10 or 15 hg, I would say that you have stuck vanes and you would need to clean your turbo.

My wifes Golf pulls like new to about 2500rpm, then falls on its face. Is this the procedure I need to follow? I can hear the turbo spool up, at least until that point.

Does it pull hard to 2500, then fall on it's face, then the next time you try pulling hard, it pulls fine?

Or does it pull hard to 2500, then fal on it's face and it won't pull again until you cycle the key off then on? If it's the later, then yes, but I suspect it isn't.

Most likely you need to find the How To on troubleshooting low power.

Drivbiwire said:

.....This issue is often caused by "Babying" the motor and short shifting at low rpms. People who have this issue are often the ones that have been being gentle with the motor and not following my guidelines of shifting at 2500rpm when cold and at no less than 3,000 rpm when warm....

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Following the guidelines above does it matter what RPM you end up cruising at? (I usually cruise at 1600+).

Hey Guys,

Read this whole thread and others related to it.

Three days ago, Friday, I was leaving work anf notice that I wasn't producing any boost. After 10 mins of driving the car, it was boosting like normal. This continued the rest of the day. Car needed to run for 5-10 mins. until I was able to see boost.

Sat., much of the same but it was taking longer to boost and I was no longer hearing the dump of the actuator. Started to throw a 1556 code.

Sunday, after inspecting all the vacuum lines, I tried to manually move the actuator rod, by hand, from the top. I would drive the car, for 10-15 mins and then work at the actuator, 15 pumps, for 3 sets everytime. I was able to move the actuator 1/2 to 3/4s a inch. I feel the spring compressing, but I have to put some pressure on it. The only time I was able to boost was the first attempt every few drives. I had to ready get on the throttle. After this, the car would go into limp mode and I would see a code shortly after, 1556.

This started pretty suddenly on Friday. I "baby" the car sometimes, but I do hit full boost and get pass 3k a few times every drive. The intake was cleanned 2 years ago.

- I am thinking my next step should be to disconnect the actuator rod and see how everything moves then. Should I try the min-vac method first?

TWSTDVW said:

Hey Guys,

Read this whole thread and others related to it.

Three days ago, Friday, I was leaving work anf notice that I wasn't producing any boost. After 10 mins of driving the car, it was boosting like normal. This continued the rest of the day. Car needed to run for 5-10 mins. until I was able to see boost.

Sat., much of the same but it was taking longer to boost and I was no longer hearing the dump of the actuator. Started to throw a 1556 code.

Sunday, after inspecting all the vacuum lines, I tried to manually move the actuator rod, by hand, from the top. I would drive the car, for 10-15 mins and then work at the actuator, 15 pumps, for 3 sets everytime. I was able to move the actuator 1/2 to 3/4s a inch. I feel the spring compressing, but I have to put some pressure on it. The only time I was able to boost was the first attempt every few drives. I had to ready get on the throttle. After this, the car would go into limp mode and I would see a code shortly after, 1556.

This started pretty suddenly on Friday. I "baby" the car sometimes, but I do hit full boost and get pass 3k a few times every drive. The intake was cleanned 2 years ago.

- I am thinking my next step should be to disconnect the actuator rod and see how everything moves then. Should I try the min-vac method first?

Click to expand...

using a vacuum is easier and it will tell you how much it actually needs to move. It should start moving somewhere around 3-5 in. vacuum.

whitedog said:

using a vacuum is easier and it will tell you how much it actually needs to move. It should start moving somewhere around 3-5 in. vacuum.

Click to expand...

Will do, and I will continue to exercise the actuator rod. Any recommendations for a mini-vac?

Something like this, http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=39522

TWSTDVW said:

Will do, and I will continue to exercise the actuator rod. Any recommendations for a mini-vac?

Something like this, http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=39522

Click to expand...

That will work fine. There are higher quality ones out there, but if you aren't using it alot it'll do.