VNT17 Odd Turbo Noise, Loss of Power, Buzzing

I went to drive to lunch today and noticed my turbo was real loud, its usually noticeable at idle and driving slow because of the stage 4 tune and it being a VNT17 but it was way louder than normal, noticed it had low power also. Then after about 2 mins all the sudden the loud turbo noise went away and it sounded back to normal had good power, driving back from store it was the same thing good power and everything, left work still normal. The turbo isnt old at all, when i bought like a year ago the turbo looked brand new.

Went to drive it after work and its loud again, whirling turbo noise like a straight piped 6.0 ford or worse, no power and hazy out the exhaust, this time it seems like its not going away, then i notice its also like a buzzy vibrating sound coming from either the wastegate area or exhaust side of turbo when i put my hand on it running. If i unplug the wastegate hose the actuator shaft drives back down and the sound goes away, but when revving it still doesnt sound right, so far ive pulled intercooler boot and pipe off and theres coatings of oil inside but no liquid amounts poured out or anything, took the turbo inlet off and i can turn the wheel by hand and dont feel any roughness or rubbing at all, dont notice any damage. Pretty confused at whats going on and no codes, not sure if VCDS would tell me anything it seems pretty mechanical.

Also checked turbo for play and there is none in and out what so ever. Had two lose intake manifold bolts, tightened those, checked all other bolts and everything is tight, turbo is loud as hell though and I can feel it buzzing specially when I put my hand on that actuator and diaphragm. Pretty clueless right now.

https://youtu.be/a-0Eg_SbyTg

Video of the sound, the n75 seems to be working, I have no codes either.

Have you tried taking the belt off quickly, to see if it changes? It definitely rpm sensitive.

The belt? its definitely the turbo i can feel it, plus the sound completely changes based on actuator position.

Still boggled...removed lower intercooler hose and its pushing air out of the turbo, with engine running I can cover my intercooler with hand and engine dies immediately so no leaks on that side of things.Removed Downpipe and exhaust side of turbo looks normal.

Okay, that is weird. I watched the video and it appears when the actuator moves the noise starts. Have you tried removing the accessory belt and seeing if the noise stops?

I'm not understanding what removing the accessory belt would do in regards to this? At this point im thinking an o ring, seal, vanes or something got damaged but still very odd. Right before this happened I noticed my boost was going a little above 26psi also. Might have caused it.

Use a mirror to look into the compressor inlet.
If the impeller is making contact you should be able to see the evidence.

Not sere how to check, but is it getting oil?

Ive looked into both sides of turbo, no play or damage.

At this point im pulling everything off the car, did about all the tests i could with it on car i need to remove to find out more.

Im either gonna fix myself and get it rebalanced or just send it out to be rebuilt, even though the wheels spin freely, maybe i can get them to just fix whats bad and balance for a little cheaper then a full rebuild. it has to be a vane issue, o ring or something.

Its possible i might just buy a 17/22 instead and just sell this one once fixed or something.

Looks like you have an egr delete correct? Double check and make sure all the nuts and bolts are tight. Any of those connections that have a metal gasket and the nuts loosen up that metal gasket will make quite a noise.

You can always get your turbo hybridized yourself and save a wad of cash. If you go to a "standard" 17/22 you will have a vnt-20 frame turbo that will spool slower than what you currently have, or if you have the time you can send your turbo out and have a 52mm or 56mm compressor wheel machined to fit. If you have any questions about hybrid turbos, you can PM me if you like, or you can ask here as well.

I so have an egr delete but there is zero noise near it. Also like I said earlier. While the engine is running I can put my hand over my intercooler and the engine dies immediately. That tells me everything from there on is sealed tight, upper pipe, Boots, EgR delete, manifold and all.

I'm used to messing around with big turbos but I'm new to vanes and how small these are which is why I'm not sure if I'm gonna tear it apart much since I'd need it balanced anyways. Good news is the wheels and shaft are in perfect condition, has to be an o ring or vanes damage inside causing this.

Reading through this and analyzing the video, one other possibility stands out to me that has yet to be mentioned.

Vacuum Pump or possibly something in the vacuum system.

I see where the noise goes away when you remove the vac line to the turbo actuator. This definitely tells you that it could be turbo related, but it is also telling you that it could have something to do with the sudden loss of vacuum in your entire vacuum system.

I would like to see what the noise does if you place your thumb over the end of the vac line, when removed from the actuator.

To me, the noise seems too instantly linear with RPM. I would assume a turbo response would lag behind RPM to an extent. I hear how the noise only changes pitch up to a certain RPM, maybe this is the point where the system has reached max vacuum. I also hear how the sound ramps up slowly when the engine is turned on or vac line plugged back in, again consistent with the vacuum pump building vacuum in the system. Poor performance could also be explained by a low/no vacuum situation causing poor control of the VNT.

Should be a very quick and easy check before you go "pulling everything off the car". If you start the car, hear the noise, pull the actuator hose like you did in the video, noise goes away, put thumb over end of actuator hose, wait for vacuum to build, and if noise comes back, you should change your focus to your vacuum system, starting with the pump itself.

Let us know the results of this test.

Well I got on vcds and made it cycle the n75 over and over and its essentially the same thing as me removing and reinstalling the vacuum line. It cycles fine everytime. Ive removed the line before and good vacuum from the line.

good luck with the fix. please post your results.

btw - I watched the vid, couldn't' help but notice your bikes. man I miss my YZ426...

Cburb88 said:

Well I got on vcds and made it cycle the n75 over and over and its essentially the same thing as me removing the vacuum line. It cycles fine everytime.

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Cburb,
The N75 can allow vacuum to the actuator, or it can isolate the actuator from vacuum. It's operation has a negligible effect on the vacuum in the rest of the system. Cycling it through VCDS does not do the same thing as removing the line from the actuator. When you remove the line to the actuator, you create a massive vacuum leak that eliminates all vacuum from the entire vacuum system.

So far, we know that removing the vac line from your actuator makes your noise go away. Removing the vac line from the actuator does 2 things:

1) Allows the actuator to return to it's natural position (points to VNT armature position having an effect on very loud turbo noise. Doesn't seem feasible IMO)
2) Eliminates all vacuum from your vacuum system (points to either your vacuum pump failing or a leak in the system that buzzes as the air moves past the source. Most feasible IMO)

Right now you are at a fork in the road. You need to isolate one from the other to determine which direction to continue troubleshooting. Perform the 2 tests below to make that determination.

1) Perform the test outlined in my last response. With the engine running and noise present, remove the vac line from the actuator. Leave the actuator vacuum line off the actuator and plug it, with your thumb or something else air tight. This will allow your vac system to build vacuum again. If the noise comes back shortly after plugging the actuator vac line, your problem is in your vacuum system. I'm thinking this is the case.

2) If the noise does not come back, then leave the line disconnected from the actuator and plugged. Use your mity vac, assuming you have one, to apply vacuum to the actuator and move it through it's stroke. Also make sure that it holds vacuum and is not leaking. If the noise returns when moving the actuator, your problem will be in the turbo. If the actuator does not hold vacuum, it needs to be replaced and is most likely the noise source as well.

Performing both tests will definitively tell you if you are experiencing a vacuum problem or a turbo problem.

Please go try what I asked. Its quick, its easy, and the result may save you a ton of time and $$.

Let us know the results.

Ok well when removing the vacuum line the actuator goes back to the up position which is where its quiet anyways. I did have it removed and placed my thumb over it just to feel the vacuum and didnt hear any further noise, although it was briefly i could do it again and just wait longer than a few seconds.

Cburb88 said:

Ok well when removing the vacuum line the actuator goes back to the up position which is where its quiet anyways. I did have it removed and placed my thumb over it just to feel the vacuum and didnt hear any further noise, although it was briefly i could do it again and just wait longer than a few seconds.

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Time how long it takes for the noise to begin after starting the car. When performing the test, make sure to keep the line plugged for this amount of time and even add another 30 sec or so for good measure.

Cburb88 said:

...................... when i bought like a year ago the turbo looked brand new..............

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What kind is it, is it a rebuild or new, where did you get it?
I interweb guess you are correct that the noise is from the turbo, perhaps only when the vanes are in a certain position.

BobnOH said:

What kind is it, is it a rebuild or new, where did you get it?
I interweb guess you are correct that the noise is from the turbo, perhaps only when the vanes are in a certain position.

Click to expand...

Its whichever garret gt1749vb or something, whichever one is the vnt 17. I hate their part numbers. When I bought it like a year ago it was put on sometime before then. I could tell by looking at it that it was very new. Just unsure of where it came from and any details besides that.

Ok so plugging the vac line from n75 does nothing at all, no change in noise. The noise appears when you put the vac line on turbo and the actuator drives down it won't happen any other way. I'm pulling off turbo this weekend to see what I find, thinking either vane damage or something else blowing out.

Sounds like you’re on the right track. Did you see if your actuator holds vacuum? Thanks for the update. Hopefully it ends up being something simple.

I didn't have my mityvac with me but it seems like it was holding considering when i plugged vac line into turbo it would draw actuator down and hold it. I removed everything from car and vanes are perfectly fine, cleaned everything in parts washer and it all looks good. I'm thinking it blew a seal I guess. There was a fair amount of oil on pipes and whatnot. I figured if it blew a seal I would have bad shaft play but maybe not, unsure of what type of bearing/seals these have. Didn't pull compressor housing apart from the center section yet. Not sure if I'm going to considering it looks like I'm gonna be sending it out to be rebuilt anyways.

Axial play is where the problems come (first). I believe that you shouldn't, unlike with radial play, feel ANY play: there is acceptable radial play- it gets dealt with by oil pressure (with no pressure you're going to be able to feel some play).

Yea I can move it up and down some not much, in and out though there is none. Something has to be blown out inside to cause my issue, plus I'm guessing all that oil i found in the intercooler and piping was from it going out. I just don't know its history and how long that oil could been in there.

I was also wonder if the seal or whatever was going out on it could have been the cause for it overboosting just before it took a crap.

Cburb88 said:

I'm guessing all that oil i found in the intercooler and piping was from it going out. I just don't know its history and how long that oil could been in there.

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Turbos pass oil. It's a fact of life. IF someone has driven a turbo-engined car with egg shells under the GO pedal then that oil will accumulate- it will not get boosted through (and burned up- controllably).

Any time someone gets one of these cars one of the very first things to do is to check the lower IC for pooled oil. If you forget to do this and then hammer on the boost it'll be a short ride to a big repair.

If there's no shaft play then it's unlikely the turbo has issues. Given you don't have the history on this car I'd just drain the IC and monitor oil consumption.

Post a video of the noise.

I know they do but there is a fine line to how much and im thinking its a little more than usual, there was a puddle in bottom of intercooler and i can see its coated inside, no idea how long its been like that either i just have to guess. Its 100% something wrong with the turbo just not sure exactly what. there is literally no other possibility with the tests ive done, noise comes from the turbo, gets changed by the turbos vanes, more vacuum applied equals more boost being asked of the turbo and its giving me no boost. No leaks anywhere and no other mechanical issues, vacuum system works good. there is already a video, ill be calling xsboost or midwest for the rebuild most likely. The car has been using a little more than normal oil also, i cant monitor oil consumption when this car has no power and zero boost, it hardly moves around and sounds like a small jet engine.