Possible Turbo Failure imminent?

I have a 2000 Jetta TDI (ALH) 5 spd that I just bought and I am starting to worry that it has an impending turbo failure.


Symptoms: Whine that sounds a little like a police siren when holding RPMs around 2000 RPM. If you give it a tiny bit of the go pedal (think feathering the pedal) it will change pitch up or down, but the noise dissapears under full throttle (either it is masked by the rest of the engine noise or it doesn't get louder). I have had others in the car who either can't hear it or when they do, they tell me it is just the sound of the turbo (the problem being I have a 2002 Golf TDI that doesn't do it, hence why I noticed it on this car.)



I have also removed both the downpipe and output side of the turbo and the shaft doesn't seem to be touching the sides (radial play) but it does move in and out a bit (axial play) on both sides. It barely moves enough to be measurable visually but you can feel it going in and out with your hand. I understand from other forums that spec play is between .001" and .004" (axial play) but I don't have a dial guage to measure it. The blades of both impellers look fine from what I saw.


I thought it may have been an exhaust leak that was causing the sound (another user had a cracked flex pipe that caused a similar issue) but I have been unable to find any leaks with the car idling. It could possibly still be a leak on the intake side of the turbo, but short of making sure all the joints are connected I don't know how to test that.


I have been keeping an eye on oil consumption and it doesn't seem to be going through much if any. There is no significant oil buildup in the intercooler or the the output hose from the turbo. The only place that seemed to have more oil than it should was the input hose on the intake side of the turbo coming from the airbox. The small amount of oil it might be using could be from a minor leak at the vacuum pump as well as what seems to be the back of the valve cover.


Other than the sound (and possible excess axial play) it would seem it is healthy. I just really don't want to just forget about it and have the turbo dump oil into the intake. (In the mean time I have verified that my ASV is working in the event of a runaway.)


Any suggestions?

Check two things: Look for a boost leak including a split hose (like the one that goes to the EGR), and check the snow screen and see if it's blocked. That will make the turbo work harder and make make noise.

If others can't hear it you might not have a problem at all: some turbos are louder than others.

I checked the snow screen and there was a little stuff in there, but not enough to plug it. As for the intake hoses, I could not find an obvious crack in them (checked the hose going to the EGR and the soft line coming off the turbo) unless it is somewhere in the intercooler hard piping.


Yeah, I get that each one will be a little different noise wise, but the last thing I want is to just ignore it and have the turbo grenade itself.

When you pulled off the intake pipe did you look at the impeller with a mirror?
The contact stripe on the housing will be visible if it's there. Cellphone works too.

Yes I used a cellphone and could not see any obvious contact points where the impeller has hit the wall. Nor could I see any obvious damage to one of the impeller blades (apparently this can also cause the turbo to scream). I am more concerned about the axial play than the radial as it feels like a significant amount when moving it with my hand, but when i watch it go in and out it hardly seems to move. The impeller also spins relatively easy with my fingers.


Unless I don't know what I am looking at and you can see something glaringly wrong with this photo:


https://imgur.com/G10JmRz

That doesn't look original...

The other thing I noticed is that the sound is most noticeable when the turbo hovers around 2 psi of boost.

I also have this problem, I was told by a TDI guru possibly one of the vanes has a bit of a disformity and depends on the air movement it whines. when I get mine up to 15 20 pounds of boost the whine goes away and typical whistle starts again.. Getting it diag-ed this weekend to be certain. FWIW

Is it worth swapping it out with another used one from a scrap yard? If so what do I check on the other one? Axial and radial play?

Terrible photo but not the original impeller/turbo.
If you can put up with the noise and there's not too much oil loss, I say keep it.

To the OP..

Obviously, the bushing/bearing/shaft has worn to the point it has allowed the Impeller to scrape the housing. Or, something went through the Impeller and only damaged the outer fringe of those blades.

To TDIGuy...

I seriously doubt that a Vane has deformed causing a whine from the Turbo. If a Vane is deformed, there's likely more than one. Also, I just cannot comprehend a deformed Vane causing an audible noise considering they are on the exhaust side. Lastly, if a Vane was deformed that bad, I'd tend to think it would bind causing the Turbo to not function properly, very noticeably. ....

It is indeed a terrible photo. So I went back out and took a better one.








I was looking at these marks on the front of the impeller and wondering what would have caused that The shaft doesn't have anywhere near enough radial play to have caused that, nor does it rub on the sides at all when I spin it. Definitely looks like it ingested something, but how it got there through the air cleaner beats me.


If it did injest something which caused the damage to the front of the impeller, that would make sense as to where the noise is coming from.



Flee, still think I should hang on to this turbo?

I vote no.....

Yea I don't know. Sounds far fetched I know. That's just what I was told on a 5 minute call into them this morning. On a Garret VNT17 with 10-15k miles on, do you have any other suggestions? Its not wearing on the housing, just a whine at low boost then quiets as you build 15 or more psi

OP, that Impeller is likely out of balance. So, how long it will last (Impeller, shaft, bushing, etc.) is no doubt debatable. What's not debatable is how much damage will occur if it breaks up and pieces make it into the cylinders.

TDIguy, I really cannot definitely say what's causing the noise coming from your Turbo.

I'll share this, only a few weeks after I purchased my 2000 Jetta in March of 2002 with 45k miles on it, after a very hard run on the Interstate (yeah playing with it), I exited. At the stop sign at the end of the exit ramp, I heard this horrible screeching sound that I feel certain was coming from the Turbo ..... pulled out into the traffic and the noise went away. Fast forward over 16 years later and just shy of 370k miles that OE Turbo is still functioning just fine. In fact, I did a TB job on the engine earlier this summer and inspected the Turbo ..... shaft seemed just fine. (My son owns the car now. I do the maintenance.)

Fair enough. I just want to get this thing going again, so I will go to a wrecker and see if I can pick up a used one in good shape.


Again, anything other than axial/radial play and obvious impeller damage I should be looking for?


Also, this may be a dumb question, but is there anyway to disconnect the turbo so that the car runs (albeit badly) just as a n/a car? I obviously don't mean disconnecting any of the air lines as this would cause the car to ingest unfiltered air, but perhaps a vacuum line going to the actuator so that the turbo won't spool at all? The only reason I ask is that I need something to drive to go look for a new turbo and I don't want to risk the turbo grenading itself on the trip if I don't have to.

Without the Turbo it will be an old dog, even on flat ground.

Seems there was a Thread some time ago where one of the TDI Club members was somewhere in Texas trying to get back home (maybe to Colorado). The shaft had broken in the Turbo. Seems he ended up pulling the guts out and blocked off the exhaust from the Intake side. Anyway, as I recall with the guts removed, it did run a bit better but was still an old dog!

Dhawk, that turbo has had some FOD that can be seen in the clearer picture.
That could be why it is making noise now.
I also had a turbo start to squeal once. It was the original on my 02 TDI.
I drove it gently for almost 6 months before I got the upgrade turbo together.
I was able to get a used VNT-15 from a member here quite reasonably that is
still going strong years later so that's an option, too.

Just testing a replacement turbo that was on a runaway engine and there is no noticeable axial play and the radial play seems to be within spec. I know that the most common cause of runaway is faulty turbo seals, but is it possible that a turbo would have bad seals and still have no axial or excess radial play?


It could also have just been babied for too long and allowed oil to build up into the intercooler. I am just trying to figure out if this turbo is still useful.