Strange howling or whining noise...boost leak? Invisible supercharger?
 

I'm getting this odd howling noise coming from my engine bay whenever the turbo spools. I haven't been able to figure out what it is or where it's coming from. Does it sound like a boost leak to you guys? (Or do I have a supercharger I don't know about!) I've checked my hoses and they seem fine...


Thanks!

Oh, this is with the older FM2 turbo kit with, new FM2 downpipe.

I've had that noise once with a coupler that was coming loose. You'll find that easy when you do a boost leak check.

The second time I had that noise, I assumed I had another boost leak. Drove the 40 miles home. Went to hook up my tester, and saw that the noise was from the compressor wheel rubbing on the housing...

https://www.miataturbo.net/attachmen...ine=1333019751

Definately sounds like a boost leak or dead turbo...both noises can sound very similar.

oh god...maybe I did blow up the turbo...

okay phew. I just checked the turbo. minimal side to side play and no in.out play. and also spins freely, no marks on housing

Bov leaking?

Don't relax just yet. When my 2560 failed, there was not a lot of shaft play and it didn't contact the housing. The tell-all was when I turned the car off and when the turbo kept spinning there was an obvious sound coming from the turbo. Physically it looked fine.

How does the turbo sound when you turn the car off? Can you hear anything distinctive or does it just kinda have a light "hissing" sound?

Oh, mine is the older sleeve bearing oil/water cooled unit. So mine doesn't spin forever after shutoff like the BB units...

My 2554 made a very similar sound this morning. Oil level and pressure looked good. The sound seemed to go away after the car got fully warm. I haven't checked for shaft play yet.

I didn't notice any unusual sounds after shutting the car off.

I know this one's kinda old, but i have the same exact issue with my TD04H today. Same noise, and will not make ANY boost. Boost gauge will get to 0 and stay (like an NA motor). Pulled the turbo off, and there is minimal shaft play (none in/out, and very limited side to side). If i push fairly hard on it while manually spinning it, it will barely touch the side. But if i just spin it normally, it doesnt hit. There might be some very slight marks on the housing that suggest it could have hit before, but before i took the turbo off, i shut the card down and watched/listened to the wheel, and it wasnt hitting. Any ideas? What was the result for you back then?

For what it's worth, this started to happen while i had it out driving it. I drove it around, and all the way home, and it drove perfectly fine, just no boost. Makes the same sound, but will not even attempt to go beyond 0psi... I checked the wastgate and its not stuck open either. I saw another post that someone else had a "clogged" cat that was the problem, but with these symptoms, i dont see that as being a possibility.