ALH turbo vnt ring wear 490k miles ...

long time customer was having overboost issues for quite a while ... actuator had a very sticky spot so I swapped out the tired original turbo for a very low mileage unit ... had a chance yesterday to peek inside, here is what i found ...


actuator arm showing significant wear


vnt control ring showing arm interface slot worn badly


this is how the parts had worn together

Wow! I've never seen anything like that.

Do you suppose that the Vanes are scrubbing the manifold housing? I've found them scrubbing which caused the Actuator to appear to be non-functioning. I used a dremel to shave off some material for clearance ,,, issue solved!

Thanks for sharing your finding!

AndyBees said:

Wow! I've never seen anything like that.

Do you suppose that the Vanes are scrubbing the manifold housing? I've found them scrubbing which caused the Actuator to appear to be non-functioning. I used a dremel to shave off some material for clearance ,,, issue solved!

Thanks for sharing your finding!

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Andy ... the turbo worked great for the better part of a half million miles and never had an issue with coking up as the driver gave it no chance to ... it's possible that wear inside the vane assembly led to high effort at the actuator arm .... this same issue with control ring/lever wear is becoming apparent in KP39 turbos with less miles so keèp your eyes open... it's not always carbon!! ... turbo was shot all the way around and had worn thrust and shaft bearings (you can see evidence of the turbine rubbing the heat shield )

Yep, I do see where the Turbine has been rubbing the heat shield!

Well, any way you look at it, that Turbo has served it's purpose well!

AndyBees said:

Yep, I do see where the Turbine has been rubbing the heat shield!

Well, any way you look at it, that Turbo has served it's purpose well!

Click to expand...

You can say that again. Though I'm sure it had to have been acting up for quite some time.

With it being worn away, wouldn't it underboost opposed to overboost?

LNXGUY said:

With it being worn away, wouldn't it underboost opposed to overboost?

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because of the wear the two parts would lock together with the vanes half closed and the spring could not return the vanes to full open hence the overboost condtion...

Yeah, can't complain, that turbo did good.... lasted a lot longer than many of the newer cars do! Thanks for posting the pics!