03 Golf TDI - VNT actuator & N75 valve questions

onehotpocket

Member
Joined
Jan 24, 2017
Location
MN
TDI
2003 Golf TDI ALH
Hello all,
Can you give the attached clips a quick watch?
https://youtu.be/dp28Aq8qt_0
The first is manually actuating the VNT actuator with a handheld vacuum pump. I have two questions about this:
Is the relative motion between the actuator and turbo arm something that needs to be addressed? It seems excessive to me, but maybe it wouldn’t cause any issues.
- The actuator return spring seems to be unable to completely return the arm, as shown in the video when I physically finish returning the arm with my hand. This is the only point in the arm’s stroke that feels “sticky” to me.
https://youtu.be/toH1oPwJRDQ

The second video is using the same pump to pull vacuum on the VAC port of the N75 valve. As you can see, it bleeds off vacuum almost as quickly as I can pump it. Is this normal? Plugging the N75’s vent line made almost no difference.
I’ve been having intermittent overboosting issues since purchasing my Golf a year ago. It is now happening multiple times every drive and seems to be worse in the cold weather. The only overboost-reprieve I’ve managed is a bit of spray lubricant on the VNT arm and some hand valve actuating for a few minutes. This made the overboosting go away for a full two weeks before returning worse than ever.
Thanks for any help,
David
 

super1

Veteran Member
Joined
Apr 19, 2010
Location
NY
TDI
none
Looks like in the first video that the actuator is bad that little bushing that goes into the lever looks worn out


Sent from my iPhone using Tapatalk
 

Mastertrim

Active member
Joined
Aug 12, 2008
Location
Central, MN
TDI
2003 Jetta ALH; 2004 Golf BEW; 2011 Golf CJAA
First vid looks like too much play from actuator arm to vane arm, no return is a bigger issue. Most likely a build up of rust inside actuator not allowing the return. n75 should hold vac.
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
To me the 1st video did show play in the bushing and it seemed like the arm was possibly not that free.
Second video, there is a vacuum leak either in the hose or the actuator.
I would connect the pump to the actuator to confirm it's holding or leaking vacuum.
There's a VW bulletin about the actuator rusting inside.
If it is rusty and leaking it could suck the rust into the vacuum system N75, check valve, and possibly the vacuum pump itself.
Hope you have a heated garage to work in. :eek:
I would remove the actuator to check for the rust and physically move the turbo arm to see if it binds anywhere in it's travel.
A few have posted moving it back & forth enough (possibly 10 minutes) may help for a while.
Others remove the entire turbo and pull the exhaust side apart to clean it.
There's posts for all of there, use the search button here.
 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Isolate the N75 and test it after blowing out any debris. It may just be clogged.
 

onehotpocket

Member
Joined
Jan 24, 2017
Location
MN
TDI
2003 Golf TDI ALH
I do have a heated garage to work in!

I forgot to mention that the actuator holds vacuum when hooked up to the handheld vac pump through the hose normally hooked to the N75.I was thinking that was shown in th first video but I was wrong.

I’m a long time lurker on the website and have used the search function, but I was unable to find answers to the bushing play or what should happen when you pull vacuum on the N75.

I will get to disconnecting the actuator arm from the lever soon. For tomorrow’s drive to work, the N18 is pinch hitting for the N75. The EGR has been deleted so I may as well use the solenoid for something.

Thank you guys!
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
I will get to disconnecting the actuator arm from the lever soon. For tomorrow’s drive to work, the N18 is pinch hitting for the N75. The EGR has been deleted so I may as well use the solenoid for something.
When I changed my actuator I found it easy to get the clip off w/o loosing it but I lost a couple trying to get it on.
I wound up tying a piece of string to the clip so when it flew it was easier to find.
My N75 seems to leak internally also. :(
 

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
https://youtu.be/dp28Aq8qt_0
The first is manually actuating the VNT actuator with a handheld vacuum pump. I have two questions about this:
Is the relative motion between the actuator and turbo arm something that needs to be addressed? It seems excessive to me, but maybe it wouldn’t cause any issues.
Either the bushing is missing or the center of the actuator is worn out. There should be no slop between the actuator rod and the VNT lever. Your vanes appear to have over 5mm of uncontrolled movement because of this.


  1. Replace the actuator.
  2. At idle, measure the vacuum supply present at the N75
  3. At idle, measure the vacuum signal being sent to the actuator from the N75. Ideally should be >18inHg but the aftermarket replacement Pierburg N75s I've seen coming from the trusted venders only send 15inHg.
 

FasterXR4ti

Veteran Member
Joined
Nov 14, 2004
Location
Gilroy, Kalifornia
TDI
Passat,1997,silver
To wrap up my contribution. I ordered and installed the actuator adjustment rod end purchased through Amazon for $8.99. Works well. Here is the old one with 300K miles on it.
[/IMG]
 

onehotpocket

Member
Joined
Jan 24, 2017
Location
MN
TDI
2003 Golf TDI ALH
To wrap up my contribution. I ordered and installed the actuator adjustment rod end purchased through Amazon for $8.99. Works well. Here is the old one with 300K miles on it.
[/IMG]
Well look at that! I was unable to find just this piece. I think I'll try this as my actuator holds vacuum.

The N18 did a nice job for a couple weeks. I only went into limp mode once using it. I ended up ordering a new Pierburg N75, but since installing that I'm back to fairly regular overboost codes again. There is definitely a problem with the actuator bushing so I'll replace the adjustment rod, then post updates. Could still end up removing the turbo for a good cleaning, though.

FasterXR4ti, did you leave the actuator in the vehicle when replacing the rod? Then go through the calibration procedure using a vacuum pump?
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
onehotpocket;5374494did you leave the actuator in the vehicle when replacing the rod? Then go through the calibration procedure using a vacuum pump?[/QUOTE said:
Once you have the clip off the arm you might as well take the actuator off, it's only 2 more nuts.
Will be a bit easier to work on it.

Also turn the actuator upside down and bang it a few times to see if there's rust in it. VW has a bulletin about it.

Before reinstalling it work the arm on the turbo full range to see if it moves free through the full range.

Some have indicated if you do it a few minutes it may break up carbon buildup.

When you reinstall tie a piece of thread to the C clip so if it slips & flies it's easier to find. :)
 

FasterXR4ti

Veteran Member
Joined
Nov 14, 2004
Location
Gilroy, Kalifornia
TDI
Passat,1997,silver
FasterXR4ti, did you leave the actuator in the vehicle when replacing the rod? Then go through the calibration procedure using a vacuum pump?
I took the actuator out before replacing the end. The clip is the only difficult part of the job. As suggested here, I tied a thread onto the clip before trying to reinstall it. I also tied a small washer onto the other end, as the thread was also hard to see. Took about 5 tries before success. I did use a hand held mityvac to adjust the travel. I found it better/easier to feel the movement from up top as opposed to visually observing it from below.
The part from Amazon arrived days sooner than estimated BTW. IIRC the seller is in Texas.
 

onehotpocket

Member
Joined
Jan 24, 2017
Location
MN
TDI
2003 Golf TDI ALH
Sorry for the late update. I ordered a new adjuster per FasterXR4ti (thank you!!) and installed it about 3 weeks ago. While I had the actuator removed I worked the vane arm back and forth until I thought my arm was going to fall off. It was definitely sticky but loosened up as I worked it.

Here's the new adjuster vs the old:



I stripped the "casing" of a twist tie back a little ways, slipped the wire under the still-installed e clip, twisted it tight, then gave the twist tie a tug while I applied a little pressure with a flat blade screwdriver. Worked like a charm. Even reused the clip.


3 weeks and about 1200 miles later I have yet to have overboost/limp mode. We'll see how long it lasts. Splitting the turbo may be in my future.

Here's the actuator function (with a vac pump) after the R&R:
https://photos.app.goo.gl/iwLHTm9ZnaqeQodu2

Thank you guys for the help!

David
 

FasterXR4ti

Veteran Member
Joined
Nov 14, 2004
Location
Gilroy, Kalifornia
TDI
Passat,1997,silver
While I had the actuator removed I worked the vane arm back and forth until I thought my arm was going to fall off. It was definitely sticky but loosened up as I worked it.
I also did this, but after I installed the new adjuster. I used the mityvac from up top to help move it. It was just sticky at the endpoints of travel probably due to the adjuster becoming a slot when the bushing wore and fell out. Mine also failed at ~300K miles. Amazing that the vacuum diaphragm can last that long. Good idea on the twisty-tie. Always more than 1 way to skin a cat.

Thank you for updating. I was wondering how it went.
 
Top