Turbo Noise...Boost Leak??

[ame=http://www.youtube.com/watch?v=ht8-dMd3YFA]05 Legacy Turbo noise - YouTube[/ame]

 

Ok. I recently blew the turbo (banjo bolt screen got me). A new turbo has been put on the car. Since the install (couple days) I have been hearing a whine/squeal while the turbo is spooling.

 

My mechanic and I did a smoke test to see if there was anything loose. No smoke came out. We have not done a boost leak test yet. The turbo is brand new so I dont know how there would be any shaft play or anything.

 

In the video you can only hear the noise when I let off the gas, around the 11, 20 and 45 sec marks. Listen hard. You cant hear the noise other than that in the video because of the exhaust, but it makes it consistantly when the turbo is spooling.

 

Going to do a boost leak test and check to see if there is any play in the turbo next.

 

Car has a stock turbo, turbo back Cobb exhaust, custom tune running 17 PSI, 5EAT, 74,000 miles.

 

Anyone think its anything different than a boost leak??

 

Thanks in advance!

Not what you want to read but why are you never going over a certain RPM (3500ish?)? Are you not spooling correctly? Almost like ya got a trans brake on it or something?

 

Seems odd.

^-- I knew something didn't sound right from the video but now that OCD pointed it out, that's exactly it. It stays steady at 3500 and that doesn't seem right... it's not a CVT so it should still rev up somewhat, even with the torque converter.

 

With regards to the sound, it almost seems like a BPV problem...

But his speed keeps climbing with the same RPMs.

[ame=http://www.youtube.com/watch?v=7SxDL0mAXGw]05 Legacy GT sport mode - YouTube[/ame]

 

In the first video I would hit the throttle then hold back once I started to hear the noise. Im nervous to rev out the car. I added a second video while in sport mode, you cant hear the noise as much, but I rev it out more and you can see the gear change. Dont mind the camera work

 

If the TB hose was not fully sealed up to the TMIC would it cause the noise Im hearing as well?

Stock blow off valve?

Stock blow off valve?

 

 

Yes sir

that's how the auto works he was in 4th flooring it. if you hear a noticeable amount of air if make sure the ic to tb hose is good and the clamps are tight.

my powerstroke did the same thing sounds like a blown turbo

my powerstroke did the same thing sounds like a blown turbo

 

Turbo is brand new. It made the noise right from the start after it was installed.

 

I really hope its not blown

Does it make the noise when you're in neutral/park and you rev it (you have to pump the throttle a bit) to build a bit of boost and then let off?

I hope it's not blown either man, did it come with a warranty ? But that's the same exact sound mine made. Keep us updated

I have tired revving it in neutral and it does not make the noise. I haven't tried pumping the throttle.

 

It only seems to make the noise when under load.

Right, that's why you pump the throttle, to induce at least a small amount of load in order to build boost.

I don't think it would make that noise in neutral because your not in boost. Try doing a boost leak test

Ok. I will try pumping the throttle. Doing to boost leak test this weekend.

Is it a peeee-yooouuuuu noise or is it more like a flutter?

 

I'm thinking it's compressor surge. Check your wastegate and BPV to make sure they're hooked up and working properly. You might need to adjust the stroke on the wastegate actuator to make sure it's opening at the proper pressure.

The noise almost sounds like a supercharger whine. It stays constant as the turbo builds boost.

 

Ok. Tired pumping the throttle while in neutral to see if I could hear the noise...heard nothing. Mechanic did a boost test this morning and said there were no leaks. Also took off the downpipe to check if there was any play in the turbo and to inspect everything. He said everything was fine there.

 

How would you adjust the stroke on the wastegate actuator? Would this be something they adjusted when I got my car tuned? Then when the new turbo went on it needs to get adjusted again?

 

Car builds boost fine, pulls nice, and doesnt seem to be down on power at all.

Noise seems to be coming from the passenger side

Sound like an exhaust gasket leak upstream of the turbo. As boost builds so does back pressure. A very common point is the collector to up pipe joint. The bolts are in the plane opposite of the separation force (toward the outside of the car). The multilayer metallic gasket can act like a reed valve and buzz or squeal. Sounds similar to a turbo squeal but deeper and heavier.

 

If this is the case, you can loosen up the collector and cross pipe bolts (all of them). Tighten the up pipe first and then the others. If it's silenced then you've isolated the problem. If it comes back, time for new gaskets. You can also slide the gaskets out in the process and see if there are any heat marks where the exhaust was escaping if it's been happening for a while. My guess is that your new turbo put slightly different pressure on the up pipe which has created a leak path so it probably hasn't been going on long enough to show up on the gasket or flange. When this happened to me, I couldn't feel any exhaust pulses at all under idle. Nor could I hear anything like when you have a bad gasket or cracked header. Only under load was it evident. It's a 1 hour fix as long as your bolts aren't rusted so it's worth trying.

So the noise has finally been fixed. After changing the turbo inlet tube and exhaust gaskets I found out that my mechanic never did a boost leak test. So once the boost leak test was done we found that the plastic end had separated from the core on my TMIC. Replaced that and noise was still there. My mechanic has been speculating this entire time that turbo itself was making the noise. It's good to note that the turbo was rebuilt. Mechanic called the guy who rebuilt the turbo and he said that the seal between the compressor housing and the turbine housing might not be good and air might be getting in creating the noise. The VF40 turbo using RTV silicone to seal the sections together. So at this point it didnt look like it could be anything else. Pulled turbo, pulled it apart, resealed and reinstalled. Noise is gone!! Mechanic said that the RTV was pretty light.

 

Lucky this whole thing didn't really cost me much. Mechanic has been doing all the labor for free with me buying parts. He said that the car wasn't making the noise before he got it and wanted to get it right.

...He said that the car wasn't making the noise before he got it and wanted to get it right.

 

Sounds like you've got an awesome mechanic! I may be wrong but I thought I read somewhere on here that basically anything over factory boost pressure causes catastrophic failure on the factory IC end tanks? Do you have plans to upgrade the intercooler or can you run that kinda pressure on the factory unit?

I know that a lot of people are running higher than stock pressures on the stock TMIC. My tuner said he has seen 20 psi on stock turbo and TMIC. Now I don't know how long that lasted, but I think around 17 psi is fairly standard on the stock IC. There is also an option to "bullet proof" the stock IC. A member on here sells kits to accomplish that. I have no plans of going for an after market IC right now unless it becomes an issue.