No boost and strange noise after replacing failed turbo

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
SOLVED - No boost and strange noise after replacing failed turbo

I had my original turbo fail yesterday morning, while on my commute to work.
The symptoms were a bang or pop, followed by loss of power, and a white cloud in my exhaust.
Once I got off of the road, I also found oil dribbling from behind the engine.
Once I had the car towed to my garage, and I had it up on jack stands, I found that the oil was coming from a split in the downpipe, just after the elbow.
A newly rebuilt turbocharger with a complete center housing replacement was installed, using a new braided oil supply hose and a spare downpipe salvaged from a scrapped car.
After installing the new hardware, I primed the turbo oil supply by cranking with the injection pump unplugged, 20-30 seconds at a time, multiple cycles.
When I finally reconnected the injection pump and cleared the fault codes, it had no boost at all.
Once I tried revving the engine off of idle, it almost immediately made a short screeching noise, which prompted me to shut it off.
Does anyone know what may have been happening, other than a bad turbo cartridge?
I haven't pulled the inlet hose to check rotation yet, as by the time I had everything buttoned up, it was dark and getting cold, as well as just wanting some time to think about it before digging into it again.
Any input would be appreciated.
 
Last edited:

Meister Kraft

Well-known member
Joined
Mar 6, 2016
Location
Bellevue, WA
TDI
2001 Jetta
After installing the new hardware, I primed the turbo oil supply by cranking with the injection pump unplugged, 20-30 seconds at a time, multiple cycles.
When I finally reconnected the injection pump and cleared the fault codes, it had no boost at all.
Once I tried revving the engine off of idle, it almost immediately made a short screeching noise, which prompted me to shut it off.
Does anyone know what may have been happening, other than a bad turbo cartridge?
Take the night off and relax that’s my advise, it is cold out tonight and the rain is coming. I’ve done more damage than good when i’m frustrated.

I would Clean the oil out of the plastic inlet tube to the turbo and the pressure side to the intercooler. It sounds like you may have an air leak from bad fitment from oil expanding the rubber parts or and exhaust leak.

The best way that I know to find leaks is with a smoke machine, if you don’t have that tape a paper towel to a stick and look for soot or a lot of movement on the exhaust side. Also disconnect the down pipe to see if the oil has clogged the cat enough to raise back pressure.

Edit:

I found a post about the EGR system being added on in the last 4 days, check over that system for leaks also. A cracked egr cooler can whistle an awful noise, only seen it once but it’s worth checking.
 
Last edited:

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Daughters car, 2005 Golf TDI Mine, all 5 spds
Make sure all the connections for the egr pipe are secure and tight. Those metal oval gaskets are like a reed in a musical instrument if you don’t get the bolts tight, they make an incredible noise. A high pitch screech.
 

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
The downpipe was ruptured at the flex joint, just after the turbo flange, so I replaced it from a car that was parted out.
I'll check all the joints again, but I'm thinking that at least SOME boost would show, if there were minor leaks.
I checked that all the boots were fitted after the initial test, and they were.

Using Torque app to monitor boost, it actually showed slight vacuum on the gauge, increasing with engine rpm, instead of any boost. 1.9 inHg at idle, to 3.2 inHg at higher rpm.


I'll definitely check the plumbing again, as well as talking to the shop that rebuilt the turbo to see if they have any input.
I'm planning to pull the intake hose back off to verify that the turbo is actually freely turning. I definitely remember checking end-play, since that was an issue before that turbo was sent to rebuild, and which drove the replacement of the rotating assembly.


My car's old turbo failed dramatically. I thought it was just an oil seal failure, but once I got the downpipe off of the exhaust side, I realized that there was ~1/2" of axial motion, and freely wobbling as well. It appears to have split shaft supporting the wheels...
I got LUCKY that there was not a runaway condition.
 

Mike_04GolfTDI

Top Post Dawg
Joined
Nov 19, 2003
Location
Richmond, BC, Canada
TDI
Mine: 2019 Golf R DSG, Wife's: 2015 Golf Comfortline TDI
Before putting the rebuilt turbo in, did you check if there was any debris from the old turbo in the intake ducting? Something might have gotten sucked in immediately and jammed the new turbo.

If that's not it, then my guess would be that the rebuild was just no good.
 

Meister Kraft

Well-known member
Joined
Mar 6, 2016
Location
Bellevue, WA
TDI
2001 Jetta
We can get 2 birds with 1 stone if you undo the down pipe. You can check the turbo charger wheel, run the vehicle to see if boost returns or the whistle/reed noise is gone. If that works then we know the exhaust is the issue.

When a turbo dumps oil in the exhaust the converters can plug from oil cooking itself.
 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
I understand that a new turbo costs more than a 'rebuilt' one. But...
Check the runout at the impeller and for contact on the housing.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2005 BEW Wagon
...or we can skip ahead to where did the "completely rebuilt" turbo come from. :)

A vacuum line accidentally left disconnected during the swap could cause these symptoms as well.
 

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
The rebuild was from DFIS in Portland, and after talking to them this morning, they were asking for me to send in the new turbo.
That said, I am pulling the intake and checking for free rotation tonight.

I was checking to see if any of the vacuum lines could have been incorrectly reinstalled, but the only three disconnected would have been easily discovered.
VNT actuator, EGR valve, and the short line from the ASV solenoid to the ASV actuator.

The cat should not be an issue, since it was replaced with one from a neighbor's car that was sideswiped by a work van. He'd been driving it regularly until that happened.
 
Last edited:

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
So, after pulling the intake hose off of the turbo, I found it spins freely, with no detectable axial or radial motion.
I'm scratching my head now...

I unplugged the N75 valve, just to see if anything changed, and the screeching went away.

Using VCDS group 11 to test the N75 valve at idle, it does nothing.
EGR test worked as expected, but none of the manifold pressure tests ever so much as twitched.
 
Last edited:

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
Based on a distinct lack of screeching when the N75 is disconnected, I am curious if it's possible to somehow reassemble the vnt blades in a way that they could touch the hot side of the rotating assembly when actuated?
 
Last edited:

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
Sounds like the blades are striking the housing when boost is requested. When you disconnect the N75 it can't make boost, so no noise. Why? Not sure. Lots of possibilities, including faulty rebuild, foreign object damage or oil contamination damaging the shaft after install, boost leak somewhere else in the system. Those are some.
 

Blacktree

Veteran Member
Joined
Sep 9, 2015
Location
Central FL
TDI
'02 Jetta 5-spd
I think if the VNT actuator is adjusted incorrectly, it could cause the vanes to interfere with the turbine wheel. You can probably test that by applying vacuum to the VNT actuator with a MityVac (or something similar), and trying to manually spin the turbo.

The bad news is, if that's what's happening, then your new turbo is junk. Because the vanes and the turbine will both be damaged.
 

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
So, last night I tested a few different things, including applying vacuum to the actuator while it was at idle, which did not cause any noise.
Idle may not have had enough airflow to spin up the turbo.


The shop that did the rebuild is sending another center cartridge assembly, so I'll be swapping the CHRA next week, and taking a close look to see if I can find anything obvious.

I'm thinking to try disconnecting the intercooler plumbing from the turbo and the EGR valve, and plugging both ends. I can apply pressure from a regulated source, which should show if there are leaks that part of the system.
That said, it never indicated any boost, so I doubt that it's a split in the air path.


Testing the Group 11 functions in VCDS last night, I saw and heard change to the engine RPM when the EGR N18 solenoid was tested, but no change at all when the VNT actuator N75 solenoid was tested.
With the engine off, I could hear the actuator moving with the test, so it appears that the N75 works, just something appears to be off in the turbo.
 

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
The problem had been resolved!
The noise ended up being a loose gasket in the exhaust manifold to cooler joint, and one which I could have sworn if checked twice before.

The turbo also may have had a vane loose from the actuator ring, as I pulled the center assembly to get a look at the actuator ring, and noticed an extra empty space, at about the 2 o'clock position.
I realigned the vane levers and reassembled the turbo, and then saw the exhaust leak.
After tightening the two nearly impossible to reach nuts, it seems to work perfectly.

I will be informing the shop of my findings, but wanted to close the issue here as well.
 

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Tacoma, WA
TDI
2000 Jetta TDI
Yep, I'm glad it wasn't something catistrophic internal to the turbo, and that it was relatively easily remedied.

Now I'm interested to see how many of the little issues the failing turbo was the cause of.
Already I have noticed a major reduction in the amount of exhaust visible in a following vehicles headlights when accelerating from a stop at night. I only saw a faint haze, and briefly at that. Prior to changing the turbo, I would see a fairly heavy base, and for much longer, assuming that I continued to keep the engine under more than a light load.
It also seems to have a smoother boost response, without the surge to 21-22 psi that I had seen for most of the time that I have owned the car.
I saw a max of 19 psi in my test drive, though I didn't keep it heavily loaded, as it was only a short length of roadway that I had for the test.

I'm hoping for an improvement in fuel economy, as I'd been slowly loosing some, recently floating around 40 mpg, in mixed driving. Time will tell on that part.
 
Top