Guys, I've noticed a few times that, while the car is cold, there is a buzzing noise, I believe, from the turbo. If I rev the engine a few hundred rpms higher the pitch of the buzz goes up and it gets a little louder. This same sound sometimes happens under moderate to heavy boost once the car is warmed up. I would get video but catching it is difficult at best. I'll make an attempt in the morning. The noise doesn't normally happen once the engine is warm and the oil has gotten to working temperature. Anything else it could possibly be?

 

Buzz? That one may be hard. Buzzes are usually vibrations. Check your timing belt path, is all that stuff good?

 

if the turbo bearing was bad it would grind not buzz... Plus you would not be getting any boost if it was blown out

 

Before you send us down the garden path ..... are you guessing at the source of the noise from sitting inside the car or have you been under the hood searching when it occured ??
If you are guessing from inside you might still be right but it would make me question your choice of the source more.
Buzzing is more electrical and the two actuators on the turbo are both vacuum operated so that's unlikely.

If you can capture the sound that would be a huge help.

A common term for the noise the IAC (idle air control motor) makes if it's having problems or needs to be cleaned is "buzzing" but it's on the other side of the motor.

It could also be that your idea of buzzing and ours is quite different The bearing inside the stock turbos and some of the upgrade choices are a semi-floating sleeve.

This is an article that explains the bearings. You can get an idea of what's going on in there.
AutoSpeed - Turbo Bearing Tech - Part One

Looking at the picture in the article gave me an idea. The turbos BCS (boost control solenoid) is electric and is supposed to be attached to the air filter housing or like mine laying on top of the transmission between the filter and the distributor. It is electric and if it malfunctioned could buzz by switching on/off rapidly Just a though. Should trip the check engine light though.

 

Well, when I say buzz, it's as if something is spinning off center. I have narrowed the noise to the back of the engine. Another small symptom is that my boost levels won't go past 9psi max and it's usually steady around 7psi or so. I have an aftermarket gauge and a boost controller that I originally set for 12psi and even maxed out, I'm not getting any more pressure. I checked all the hoses and they are tight and seem to be fine. I can't think of anything else. The stock controller is still plugged in but not doing anything.

 

No one else jumped in so I'm going to guess at the rubber diaphram. I have no idea why but they do rip and I'm wondering if there is enough vacuum or pressure on it that it could buzz ?? A little flap of rubber fluttering ??


Like I say, I'm really reaching with this one ........

 

To be honest, I think you may be right. My recirc valve chirps when I let off of hard boost. It's almost a "pew pew pew pew" sort of noise. I'm trying to catch the buzz but it's a little difficult. The chirping recirc is easy and loud.

 

don't catch too much of a buzz

 

I would have thought of that one if it were two weeks ago.

I just thought of how to describe the buzzing sound. I'm sure some you guys have worked with a Dremel tool. It sounds like when worn out collets and bit shafts cause the bit in the tool to spin loosely and buzz. That's as close as I can get. If it's not the recirc valve, I need to rebuild the turbo anyway. The thing has never been serviced and it leaks a tiny bit into the exhaust. It smokes like a freight train when taking off after idling for 5 minutes or so.

 

Here is a video with some of the noise I'm hearing. It may not be very audible but to me, it's a very rough sound. The camera may not pick it up well. I disconnected the wastegate entirely and I still can't push more than 9-9.5 PSI with the pressure line capped off.

 

It isn't very clear in the video but there is a chance you might have a catalytic converter starting to come apart.

It would fit the buzzing and also create back pressure that would stop the turbo from building boost. If it's in it's early stages of failure ??
If you're leaning over the engine the noise would seem to be coming from the firewall / turbo area.

You might want to jack it up and gently bump the converter with your hand to see if you hear any rattling from inside.

Or ... it could be a turbo with a bad bearing that's just dragging too much and needs an overhaul. You can get a cheap kit for around 50 or a better quality OEM from MHI (Mitsubishi Heavy Industries) on ebay for around 100. Either way you'd have a fresh turbo and eliminate it as the problem. They aren't that hard to rebuild.

 

As far as work, can it be done in a driveway in just a few hours with a floor jack, two jackstands, a torch, and a really good tool set? I hardly have time to work on anything since, when I don't work, I'm only free until around 3. I know the rebuilding itself will take around 30 minutes to do it carefully, but the only concern is getting the turbo off the car and back on in a timely manner.

 

You'd really need more time.

The big thing is cleaning. If you're rushing it's more likely you'll make a mistake somewhere and be worse off than you are now.

 

Well, the buzz has become a grind. I'm off for THREE consecutive days this week. This job is absolutely going to be done. I'll start breakdown in the morning Tuesday since it'll be warm here. Hopefully I'll be done quickly enough. Is brake cleaner fine for cleaning it or is it too harsh?

 

If you're talking about the turbo, carb cleaner will cut the crud easier.

 

Update, the turbo is grinding almost steadily under any boost at all. I'm rebuilding it tomorrow. There's no way around it. Something I've just thought about, aren't the wastgate springs on these set to 9psi or so? I think I may need to replace my actuator. I recall turning my mbc all the way down and only making 4-5psi.

 

If it's grinding you are lucky to be making any boost. Until you take care of the rebuild I wouldn't worry there is another problem in there. It's more than likely the turbo can't spin up to supply much right now.

The sooner you tear it down less chance you have of the vanes hitting the housings and trashing them all.



Or the bearing seized and the shaft spinning on it, ouch !!

 

Well, the rings were shot to hell and the bearings were loose. I had about 1mm play in all directions, axial and lateral. Now I have another minor issue, the heat shield on the exhaust side has come loose. I can hear it rattling around. It's off and on too. What might I have done wrong?

 

When it's "On" again hold it closer to the monitor and I'll try to figure out what you did (or didn't do).