Whining noise with boost

[Schwamm]

My car randomly started making a whining noise when the turbo spools up. It's always had the faint whistle under boost, but this is a totally different sound. It still drives fine, and it seems to build boost (it doesn't seem to bog down).

What could be the cause of this? I have to be driving to recreate it so I have a hard time pinpointing what's making the noise. After digging through the forum, it sounds like it could be a turbo problem but I'm unsure how to diagnose it. I have to pull the turbo out with the exhaust manifold in the next few days to fix an exhaust leak anyway.

 

[tweety2300]

Could be from the leak or bearings going bad, I'm dealing with the same thing.

Does it get louder as you drive?

 

[Schwamm]

I think the leak has been there for years and only recently gotten worse, whereas this whining noise started very suddenly, so I'm not sure the leak is the cause.

I haven't noticed any change in the sound as I drive, anytime I accelerate hard and get into the turbo I hear the whining, whether I've been driving 30 seconds or 10 minutes. I haven't driven it like this more than about 10 minutes though, so I can't say beyond that.

 

[thecrash91]

if you have a boost leak (especially if youve had it for a long time) you can overspin your turbo, which will cause premature bearing failure. but that doesnt seem to be the case, as you said it was an exhaust leak. Where is the exhaust leak located? On the turbo manifold, or after the turbo?

 

[Schwamm]

I don't know about a boost leak, but I do seem to have an exhaust leak above the turbo, between the manifold and the engine. This is just speculation based on what I can see and hear though, I haven't fixed it or run seafoam through it yet. However, I can see exhaust/smoke come out above the manifold in one corner when I rev the engine. It looks identical to the beginning of this video:
http://youtube.com/watch?v=V7IEsiMVIyg

Thanks for the help!

 

[Schwamm]

I pulled off the intake hoses and checked the shaft on the inside of the turbo for play. There was only a little play in it, and it spun freely, so I guess I've ruled out bearing failure. Any other ideas?

 

[Schwamm]

Did more investigating, and realized there is oil residue in the intake side of the turbo. I guess the seals gave out after 122,000 miles? It could also explain why oil is leaking around the exhaust manifold.

If I'm on the right track here, I need a new turbo. I researched here and it seems like my best options are a GT25R, GT28R, or GT28RS. Any advice on any of these, or where I can get a good deal? I prefer a new or slightly used one, but I'd like to avoid spending $1000 if possible. I don't care about getting a more powerful turbo, I just need a replacement.

 

[KrayzieFox]

How much oil are we talking? A little oil in the intake is common and unrelated to the condition of the seals on the turbo.

 

[Schwamm]

If I wipe the inside of the turbo with my finger it comes out black and feels moist. It's not dripping out, it's more like a film. Here's a pic:

I noticed the oil leak before this turbo noise, and I posted about it here: http://www.mazdas247.com/forum/showthread.php?123829782-Help-identifying-cause-of-random-misfire
I figure it could be related?

 

[Cleverfrog]

why 2 threads with the same issue then?

 

[Schwamm]

Well, I started a thread about why my O2 sensors kept dying every few months, and then a few days later I started one because the turbo was making this whining noise. I didn't think they were related, although now I'm realizing they may be? Anyway, it was unintentional

 

[Schwamm]

I fixed the issue this weekend. Turns out it was a leak in the intercooler pipe. I have the original plastic ones, and I had to put JB Weld and superglue around the small joint where the BOV connects. We'll see how long that lasts. Thanks for pointing out my turbo is probably ok, it's running great now! I was about to go buy a new one...