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Discussion Starter #1 (Edited)
I have a small probably not critical issue that has come up and I wanted to post it up on here to see if anyone has had this problem before and has some insight on what to look for.

At high boost (30+) under load I have a distinct loud whistling noise coming from my engine bay. I noticed it for the first time this weekend pulling my boat up a long steep hill. I was cruising along at about 60 and got to a steeper part and the engine kicked down a gear and the boost started building and the whistling started. The interesting part is it also seemed to matter how fast I was going because as I slowed down the whistle went away but the boost stayed the same. I tried to replicate it on flat ground but it seems that the hill/high load had something to do with it too.

I plan to check the exhaust bellows and go over my intake connections to see if I can find something loose or torn but with it only doing the whistling at high boost and high load its kind of a hard issue to replicate to check to see if it is solved. Has anyone else had something like this happen ever?

Info on the truck: 06 with EGR delete, SCT +65 tune, CST EDGE INSIGHT, 5" Straight pipe, New OE turbo with less than 25k on it.

EDIT: I should also add that I have had an intake leak in the past where my intercooler-in coupler blew out of the clamp and this sounds similar but vastly milder, hence me going to check the intake connections for leaks. Maybe its time to run a lower boost tune...
 

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If its not exhaust, or a slipping water pump pulley, you can check with a boost detector. You can order one from diesesite, or around half the price fashion one yourself from a rubber pipe cap from home depot and a worm clamp, plus various air adapters. I spent so much chasing an exhaust leaks and boost leaks down, and I found them, but the high pitched squeal I heard was from a slipping water pump pulley. If yours souns like that, may want to start there. Very cheap repair. You remove the pulley and scuff it, and fixed.

 

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Discussion Starter #3
That definitely sounds similar to mine but mine only will do it if it is under heavy load towing, which wouldn't make sense since the belt drive has nothing to do with the load on the engine. nevertheless I will go ahead and scuff that pulley when I get a chance just to eliminate that as an issue.

The leak I had solved a while back I did not replace the coupler just put it back on and tightened it. It is entirely possible it is still leaking at high boost, the sound sounds really similar to when that was leaking. I will replace that coupler with a brand new one and I am going to go over all my other intake connections. I also was thinking that it could possibly be my air filter pre-filter cover making noise when under high boost (cold air intake). Ive had a similar noise from a restricted cold air intake before on my old silverado.
 

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My whistle only appeared going up a 6% grade and towing my 11k fifth wheel. It gradually got worst, but only pushing the engine while towing, never slick. BPD used to have a pdf on their website that explains how to do this, but its been removed. There's some things on google about a glazing on the water pump pulley doing this. I used 3m pads on the drill to take off the glaze.
 

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I had the same on my 03 6.0l high pitch whistle while towing up a steep grade it eventually got worse and lost speed and power while towing hills ! Turns out it was losing boost from a crack in my Y-Pipe ,check bellows and exhaust.
 

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Discussion Starter #7
I have not. I did bring it to a guy and have him pressure test my coolant system. Both cold and at operating temp. At cold he pushed pressure into it while the engine was off to see if there were any leaks and it did not lose pressure or fluid. At operating temp running he had me put the truck in drive and hold it at 2500rpm for 5 mins while checking to see if the pressure rose at all during that time and it built less than 0.2psi over the 5 mins. He concluded that my coolant system has no leaks and is not being pressurized by exhaust gasses.

As an update to this thread I recently drove my truck over 250 miles round trip on highway and residential type roads and did not hear the noise at all. Before I went I went through and tightened all of my intake connections. It seems the issue has been solved by tightening the clamps.

I also have been paying close attention to and checking my coolant tank. It seems that it really does move a lot more than stock. At operating temp (over 180 ECT) It sits right above the low mark in the degas bottle, at stone cold (20 Ambient temp) it sits about 1-1.5 inches above the bottom of the tank. You can hardly see there is any coolant in there when its cold. I think I just thought it was empty before because I didnt look hard enough for fluid. I did add a gallon of coolant but I filled it up above the low mark and it did push some out right after I added it. I am pretty sure I was deluded and fearing the worst at first and that nothing was really wrong at all.
 

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Discussion Starter #8
Ok so some development on this issue. I have ordered a new belt and tensioner to eliminate that as an issue. I have however discovered that the sound definately only happens when I am building boost and only occurs around 15-20psi and continues on up to max boost. I think I have a leak on the charge pipe system somewhere. I noticed also that my silicone coupler that connects the turbo to the first charge pipe is not an elbow connector like it is supposed to be. I also think it may be too short. I am going to try to replace that first as well as go through the other silicone connectors and make sure they are all connected properly. I have a Banks intercooler and an aftermarket charge pipe system with giant 3" pipes. Is there anywhere on the charge system that is common to start a leak? Is there anything else to check?
 

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You can do a boost leak pressure test through the turbo. Dieselsite sells one. It’s not to easy to see under pipes for leaks, but you’ll hear them with a pressure check.
 

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Discussion Starter #10
You can do a boost leak pressure test through the turbo. Dieselsite sells one. It’s not to easy to see under pipes for leaks, but you’ll hear them with a pressure check.
I will look into that, that might be a good route to go. I asked my Dad about it (he is a long time 6.0 owner and former Navistar Engineer) and he said to check my egr block off plate and my intake studs to make sure they are all tightened down. I had him come over and listen to it and he said it definitely sounds like an intake charge system leak. He also said it probably isn't anything major since I'm still building 30+psi of boost easily its probably just a pinhole somewhere. A damn annoying ear piercing pinhole though.
 

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Discussion Starter #11
After more research I came across a guy who was experiencing a whistling/screeching noise from his degas cap being bad. I recently replaced my Degas cap, I suppose it would be possible the new one has failed already but unlikely... I am going to put the old cap back on to see if the noise goes away just to make sure it isn't something that simple. The old cap wasn't bad just old so I replaced it.
 

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If the whistle IS coming from the degas bottle cap, then you may very well have issues with head gasket leaks.
 

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Discussion Starter #13
If the whistle IS coming from the degas bottle cap, then you may very well have issues with head gasket leaks.
I have already had my coolant system checked to make sure it isn't building pressure from exhaust gasses. I suppose it probably isn't the problem because it does it whether its warmed up or not. Im not losing coolant and Im not getting bubbling in the degas bottle at all. My first move will be to replace that turbo boot with an elbowed one to see if it just isn't sealing enough. Im going to replace the belt tensioner and belt while im at it and maybe scuff the water pump pulley to make sure that isnt slipping. The truck runs perfect and builds boost no problem it just has this annoying small whistle/screech.
 

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You can do-it-yourself an air test rig from the hardware store
test the intake and exhaust for leaks
 

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Discussion Starter #15
You can do-it-yourself an air test rig from the hardware store
test the intake and exhaust for leaks
I have seen this on youtube. Seems pretty straight forward. If replacing the boot on the turbo doesn't fix the noise I will try that!
 

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Discussion Starter #16
Ok bad news bears. I pulled off the turbo inlet to check the size of the boot so I could do a pressure check and my compressor blades are pretty chewed up and I have a good amount of lateral play. I think its pretty safe to say my turbo is kaput. Things I learned, don't trust Remans and cold air intakes aren't all that great. Luckily for me the guy I bought the truck from offered to put the new turbo in for me if I buy the turbo. He said he can get pretty good prices from suppliers for both remans and new.
 

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Discussion Starter #17
Brand new stock replacement turbo ordered. Has updated compressor housing and unison ring. Only $750 setback. Surprisingly cheaper than I thought it was going to be. Watch out for screeching noises guys it could be way worse than you think. I'm just glad I caught mine before I broke the compressor and the engine inhaled it.
 

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Did you figure why the compressor vanes were damaged?
contacting the housing, or something from the replacement air filter?
really the stock air setup works pretty well
 

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Discussion Starter #19
Did you figure why the compressor vanes were damaged?
contacting the housing, or something from the replacement air filter?
really the stock air setup works pretty well
I suspect either the compressor wheel was not changed when the turbo was rebuilt by the reman company or at some point in the life of the turbo one of the intake connections were loose enough to allow particulates in. I did some research into the S&B cold air intakes and they seem to have no complaints about letting particulates past into the compressor. I wouldn't think that passing of particulates would allow the turbo bearing to fail though. I think the problems are unrelated. The vanes were definitely damaged but I do not think that issue was related to the overall failure of the turbo. I'm just lucky that the bearing failed and I caught it before the compressor got any worse or broke a fin and the engine inhaled anything. I will be trailering it to the shop to get the turbo replaced. No way I'm driving it in its current state.
 

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Discussion Starter #20
Well ****. Another update. My turbo was definitely bad and is now replaced. However THE NOISE IS STILL THERE. It seems like it is the up-pipe connection to the turbo that is making the actual noise. I think that V Band clamp has worn out and isn't holding the connection tight enough anymore. I am going to try to replace that clamp and see if that stops the noise. If it doesn't I may then have to pull the turbo again to replace the y-pipe if the bellows has a leak.
 
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