VNT Repair Procedure

[whitedog]

Maybe you could post them ont he picture server on this site. Now we need a password.

 

[cbass94]

Quite the difference on those graphs Barny8. Could you post what mods you have, if any? I noticed that one spike right in the middle on the "after" graph and it got me wondering if you're stock or modded.

BTW, to see the graphs, you have to have a yahoo account to login.

*EDIT*Barny8, I uploaded your graphs on my account, here they are:
Before:

After:

 

[whitedog]

Thanks seabass. I've been wanting to see those pictures.

Very nice change. It's good when you can see a change like that.

 

[barny8]

Thanks, seabass, for posting the pics (I have no attachment permission). I have put the pics on the gallery now.

No mods to the engine or ECU but the cat was removed before I bought it (still legal in the UK). Maybe that explains the slightly above spec boost?

Before:
http://pics.tdiclub.com/showphoto.php?photo=30525&cat=500&ppuser=52230

After:
http://pics.tdiclub.com/showphoto.php?photo=30526&cat=500&ppuser=52230

 

[dieselt]

GREAT post....I wish I had this information when I was replacing the head and #4 piston and I was waiting for the $400.00 replacement piston. My TC is stuck at the low end of boost output...driving 2 hours a day at 70 mph with cruise on for 90% of the time is the cause.

 

[nicklockard]

Try this...

My current 99.5 Jetta Tdi has always felt dog slow and had a weird idle 'chuffle' that has been troublesome. I bought the car with 133K miles on it. I have had Oldpoopie, Whitedog, Jetpuf, and a bunch of other people try to help me troubleshoot it to no avail. We have swapped injector nozzles. We have done the hammer mod to the IP. We have adjusted IQ settings. I have tried tens of times to do "Italian tuneups." I have run every additive under the sun. I have done Arby's nozzle cleaning procedure (forgot name of additive (DP somethingorother.))

Nothing has worked.

Well last Tuesday I decided to give the VNT actuator rod & vacuum pot a workout. The car was still cooling down from a short drive. Reaching in from above with leather gloved hand, I could only move it about 3/4", or with great effort, to about 1". It made a crushing sound, like a bunch of carbon being squished. I then put the car up on jack stands and removed the lower cover. Using my gloved thumb, I cycled the actuator rod until my arm tired, pushing as hard as I could. Each time it sounded like carbon being scrunched up between the vanes. I then started the car and tried to move the actuator but could not move it against vacuum. One more time, I got under the car and excercised it, pushing with all of my strength until my arm gave out. I had move it through full cycling at least 15 times total. Each time it got a little tiny fraction better in total movement/ease of movement.

Then I got in the car and after warming it up, drove the spank out of it...no change Came back to the garage and added a 5X dose of Howe's Meaner Power Cleaner. Did another Italian tuneup. Still no more power

But the next day, I added some biodiesel so that the final percentage was B25. I then did another Italian tune up and could definitely tell a small increase in power. Normally, a B25 blend makes my car feel even slower than normal. The following day I did another on my way up to X-country ski around Mt. Hood with Jimswea (club member from Vancouver.) Even though we're both big guys, the car felt more powerful than if it just had had me in it.

This thing was finally starting to feel like I thought it should!

Over the weekend I continued to excercise the VNT actuator rod by hand, pushing all the way until my hand hurts...listening for those crunching sounds. I will continue to do this until I hear metal on metal sounds...exercising VNT rod by hand then Italian tuning. I am now able to win stoplight races against my neighbors cars that used to beat me (see the same cars day in and day out around where I live.)

Last night I decided to provoke the condition which reliably gave that idle chuffle: idling in first or second gear around my parking lot and into my garage...almost imperceptible! It used to almost buck under these conditions.

This has restored so much performance I am thrilled! Next item is to lubricate the rod with some molybdenum disulfide grease.

From now on I am going to do this as a monthly preventative maintenance item, and do Italian tune ups 2X a week. Thanks to all who've gone here before.

 

[pghPAtdi]

Maybe, just maybe the crunching sound is the spring inside the diaphragm compressing. If you can get under and unbolt the two little 10mm bolts holding the actuator on you can then move the vnt linkage without inference from the actuator. This way you can absolutely isolate the problem. VNT.....rusted up diaphragm spring.

good luck
dave

 

[nicklockard]

Will do. Thanks I didn't describe it well...it's sort of a soft 'crushing' sound...hard to quite describe. I do wonder if there is rust in the vacuum pot, so I will take it off and check it out/lube it or replace it if necessary.

 

[Biggles]

I did the same thing a week or so ago and posted here and in the UK forum

Here is my post http://kev-stuff.blogspot.com/

Different turbo, same problem, same solution, same result.

Biggles

 

[Frank M]

I did the same thing a week or so ago and posted here and in the UK forum

Here is my post http://kev-stuff.blogspot.com/

Different turbo, same problem, same solution, same result.

Biggles

You mention in the article you feel it should have more power than it now has.
Take a look at cleaning the intake and also check the MAF with VAG.

You turbo was coked and the intake will usually coke a long time before.

 

[pghPAtdi]

Will do. Thanks I didn't describe it well...it's sort of a soft 'crushing' sound...hard to quite describe. I do wonder if there is rust in the vacuum pot, so I will take it off and check it out/lube it or replace it if necessary.

Any update on your issue

 

[nicklockard]

I have not been able to remove it for inspection as work has been keeping me busy late evenings, but the driveability is excellent and the power is still there. I have continued to excercise the VNT actuator shaft by hand and now get full travel out of it. One thing I noticed is that the slowly leaking EGR seal (from small hole in front of EGR assembly) is spewing out much much more black soot all over my engine bay...probably because there is boost pressure leaking out? I am trying to locate a good EGR assembly to resolve that.

 

[Biggles]

Hi

OK my Allroad is getting better. Seems there is some sort of fuzzy logic in the chip. Things a re noticeably better in 4th 5th and 6th.

The is an article on the UK Audisport forum about a soot around the EGR. Seems this is normal(ish) to some extent.

The one thing I have noticed is I can now hear the turbo. I could not before.

My Brother in law works for Audi UK. He was in the UK tech Dept a few days ago and asked the techies in the "sorry sir this is not a customer facing department" > They reckon 90k miles on this turbo is about right before problems like this start to show.

Would seem the problem of coking or clogging is a result of gentle driving.

I don't want more BHP, I want more torque at low RPM and will be looking at a chip or remap to this end.

 

[dreamcometrue]

Hey guys...

Its my first reply and I'm proud to be a part of that site... anyways... here's a little question about that subject...

I bought a Jetta 2001 with 125 000 km 3 weeks ago and it is still under warranty for 1000 kms so I have to get it done before its done with it... I already did 4000km with it!!!

So the question is: I had a problem about a full thruttle on the 3rd and 4th gear ( standard ) and a complete lack of power... turn off the engine and start it up again by compression and everything's fine... but the problem is the following I had 2 codes... the mass air flow and the overboost code... I talk to my mechanics ( a friend who worked for 30 years for VW ) and he said that both codes were caused by the MAF... Changed the MAF on warranty a week ago, and I noticed a power gain... but that lack of power is still there when I'm full trottle on 3rd 4th and 5th... My check engine light is on, but don't know the code yet...

Another question related to that problem... is fuel efficiency affected??? If it is that problem will I get better millage???

Thanks for answering guys... I'll add a picture of my baby soon... and again I'm very proud to be a part of a BIG family... lol

NICK

 

[rdkern]

Odd to get a MAF code unless it was unhooked. I don't think that the overboost is linked to the MAF. If the MAF is bad, you might get poor fuel economy.

 

[jasonTDI]

The intake is plugged.

 

[dreamcometrue]

I don't if you were talking to me guys but I did check the connectors and no connectors seem to be empty or unplugged, but do you have any directions to know which one it is... is it after the turbo, the one near the windshield washer thing... ??? or after the throttle body???... or before the turbo??? anyways they're all connected... and the MAF is brand new but are the jobbers reliable??? I heard that they weren't too good... is it true??? I didn't see any Audi ( four circles ) or VW emblem on it... notice that I didn't took it off to look... thanks for helping and the problem is not found yet, but I'd like to know if you were talking to me guys... ??? thanks anyways... still open to more answers...

NICK

 

[astonishedboy]

I got my Turbo apart, with some heat an PB blaster. But Now how do I get it back together. I cleaned it well with emery cloth on the rim, and picked off all the carbon. Will The bolts pull to back together? Torque is 10nm, correct?

Ps. Awesome writeup, thanks for you service!

got it back together. Cleaned up and moving freely. THe Actuator lever does not reach the stop screw, however. It moves free, but just not that far. Other turbo's I have seen touch this screw. Is this necessary, or is the screw just for protection?

 

[FKH161]

Great write-up! Thanks a bunch!!

Astonishedboy, I think you might have the Vane Ring (for lack of better word)
installed upside-down. See attached image... the yellow arrow is pointing at
a small hole that should be on the "left" side of the alignment pin (yellow line).

I too had the ring backwards... causing the actuator to not be able to come
all the way down.

Hope that helps!

 

[ahlcar]

vnt

Hey Pete, I never thought I would attempt this but I was forced to do it on a car I sold and to honor my integrity. I hate pulling turbos. I found soaking the guide vane plate in biodiesel overnight really eased the carbon right off. Thanks for this wonderful pictorial. Steve. Hey, guess what else? I now have a 10 kw solar PV inter-tie system up and producing on my lot. We put up 5kw of Sharp panels and 5 kw of Sanyo panels. I wanted to see which was more efficient. So far, the Sanyo panels are outperforming the Sharp's by about 5-6%.

 

[TDI-NC]

To keep the file size to a minimum, I eliminated the removal process and kept it to strictly the repair of the turbo.

Can someone point me to a guide for removing the turbo?

TDI-NC

 

[paulv]

I tried to take off my turbo today to clean it and was thwarted by the oil feed union nut that refuses to budge and was starting to buckle the line. Is there a special very slim gland nut spanner available for this job?.

 

[unoriginal vw name]

Hi Folks,
I'm preparing to pull the turbo to clean out the soot, does anyone happen to know a place in Vancouver BC where I can aquire a nuclear grade antisieze compound?

 

[Drivbiwire]

Replace the turbo oil feed line, $45. Cut the old one if it won't come out.

DB

 

[paulv]

Heh thanks for the help. I have got the aforementioned new oil return line for the turbo at a cost of £28 in the UK. Now the job has been halted as I cannot see how to remove the flexible oil feed pipe to the turbo-the union nut for that one is hidden down on the side of the engine-do I need a special tool to reach it?.

 

[Uncle_Dave]

I have also been having this Over Boost. For the past several weeks I have been putting penatrating oil on the thing. It is starting to free up. It took three years and 100k miles to get stuck. Now that I am starting to drive a little more aggresively I should be able to keep it freed up?

Any idea of that temperatures are on these moving internals? I ask to try and find a penatrating spray that contains some antisieze. Have used Moly-Disulfide in the past. Would like to try the easy approach first.

My other problem is the Glow Plug connectors Surprize?

I live in the Boston MA area. Lots of Road Salt. I sort of get the idea that this also has to be in good condition for protection from corrosion.

 

[PrintSmith]

Only took me a month after my Jetta started going into limp and generating overboost codes to find this thread - glad I finally found it! I'd already pulled the EGR and looked at it, not too dirty, and the intake certainly wasn't plugged. I'll be checking for vacuum leaks and vane movement this weekend.

Thanks for all you guys do! It helps knowing someone else has traveled this road before me and I have some experienced posters to help me out!

 

[cha$e]

I was also having the limp mode problem in my 99.5 Jetta. This weekend I pulled the intake manifold and exhaust manifold/turbo out. When I detached the VNT rod/vacuum bulb from the rest of the turbo, I broke the little clip. Also, the rod/bulb assembly sounds like a baby rattle! I shook it for a while, and tons of particulate came out of the little hole in the side of the bulb. Initially, it took all my strength to push the rod just a little ways into the bulb...now I can get it a fair ways in (about 60% of the way to the threads) but still takes a lot of effort. Also, sometimes the rod wants to come out at an off-center angle, and it gets caught; can't quite see down in there but I think this may be due to portions of the rod rusting away? I think the rest of the turbo is fine - everything travels freely.

Any way to obtain just a replacement rod/bulb and clip?

 

[ymz]

Any way to obtain just a replacement rod/bulb and clip?

http://www.tdiparts.com/catalog/product_info.php?cPath=29_74&products_id=530

Yuri.

In Canada: http://www3.ns.sympatico.ca/roseland/VWPartsA4.htm

 

[cha$e]

Yuri

YMZ, thank you SO much!! You just saved me about $600!