Update: While awaiting my replacement actuator from CTS turbo, I pulled off the old one. Contrary to popular belief, this can be done with the turbo still mounted to the car, and entirely from the top (key for AWD guys like me).
The wastegate was indeed stuck in the open position. I assume this is not normal when the car is off?
I confirmed that it's not the actual wastegate arm that's seized; when I removed the actuator rod, everything moved freely.
Question for the mind hive: while I have the downpipe out and easy access to the wastegate mechanism, I was thinking about being proactive about preventing this from seizing in the future. Can I clean up the soot around the wastegate arm inside the turbo with some brake cleaner, and apply some high temp nickel antiseize here? That is, in the circled area below?
Or would a future build up of soot bind to the anti seize compound and run counteractive to what I'm trying to accomplish? I can also apply the anti seize compound to the external arm mechanism.
@Diggs24, any thoughts on this?
As for the actuator itself, there doesn't appear to be any obvious damage.
However, when I try to move the worm wheel manually, it does appear to bind for a moment, as illustrated in my video below:
The worm wheel teeth all appear to be fine
However I'm wondering if the inner "channeled" worm gear (which attaches to the actuator rod and pushes it forward/backward) is insufficiently greased:
If so, then I can see how this would cause sticking and, eventually, full blown failure. Alternatively, it's possible that the bearing in the middle of the worm wheel is binding
Those are my best guesses as to why this thing is starting to stick. It seems to me that there are multiple potential failure points in this design that can cause a domino effect (like failure of the clock spring, or grinding of the worm gear teeth). I also wonder if adding more high temperature grease to the channels in the internal worm gear will allow the actuator rod bushing to move more freely and prevent failure. Either way, this feels like a design that is inferior to that of the CTS turbo actuator replacement, which uses multiple reduction gears for torque transfer.
Having held the actuator in my hand and poked around its internals, I'm not entirely convinced of the conventional wisdom that a tune is any "harder" on this part. I don't see how higher boost levels will meaningfully stress any of the components. Perhaps a tune will increase the duty cycle of this actuator, which will cause it to wear out quicker and really expose its weak design more swiftly. However I'm still baffled as to why I saw failure so soon after tuning.
