Screeching at WOT

[ChvyKc]

This has been going on for at least a couple week now and I can't figure out what the problem is. The last time that I took the car out, everything was fine for about ten minutes of riding. During that time, I did a third gear pull and the car pulled hard just like it was suppose to. The next pull that I did the car makes a loud screeching noise all the way to redline and it feels like it is loosing power. Well, I finally got around to pulling the inlet hose off and checked the turbo because it kind of sounded the same as when my 14b crapped out on me. I found no shavings in the turbo and very very little shaft play.

One thing that I was thinking that it could be was the alternator. I have heard the bearings in an alternator go bad before and it sounds like that. The only difference was that those alternators did it all the time and mine only does it during WOT. I was thinking that the bearings in mine are going bad and under full throttle they are producing more of a strain on the motor which would make it lose power.

If anybody has anymore ideas, I will be glad to hear them. I just want to get this fixed so the car runs right. I am planning on pulling the AC system soon so if it is the alternator, I would like to go ahead and change it out while I am in there.

 

[ChvyKc]

Step one in leak testing is to disconnect the mbc or turn it all the way in. The bleeder hole is suppose to be there, it releases pressure in between mbc and actuator after the ball in the mbc moves back towards its original position blocking the path, this is to prevent pressure getting trapped causing the wastegate to stay open in between shifts or re-accelerating immediately after letting off.

Good to know that it is suppose to be there. I did the original boost leak test before at 15 pounds with the boost controller off, but I wan to make sure that there were no leaks around it either. I will close it all the way and do it again.

 

[ChvyKc]

Pulled the turbo and there is less shaft play in the turbine wheel than there was in the compressor and no sign of the wheel hitting the housing. I think that I did figure out the noise though. It appears that there is a crack in the turbine housing that runs down from the manifold flange into where the wastegate flapper sits. It doesn't go to the outside of the housing but the crack goes on the other side of the wastegate. The gasket that goes between the turbo and the manifold was broken in two as well. I don't know if this could cause that noise before, but it definately needs to be fixed. Looks like I am in the market for a new turbine housing.

 

[oldman]

The crack that you're speaking of is very common on all Mitsu housings, as long as the crack isn't all the way through, there is no need for a new turbine housing, blown out gasket will need to be replaced though.

 

[ChvyKc]

The crack that you're speaking of is very common on all Mitsu housings, as long as the crack isn't all the way through, there is no need for a new turbine housing, blown out gasket will need to be replaced though.

I kind of figured that it was common, my 14B has the same crack in it. Do you think that is what is causing the noise or the blown gasket? I know that there has got to be a lot of air moving past that crack when the wastegate is open so it could definately make a noise. I just want to make sure that there is no reason for me to get this turbo looked at before I put it back on the car.

 

[oldman]

Do you think that is what is causing the noise or the blown gasket?

Possibly but I doubt it, I still think it's the crank pulley to be honest but it all depends on the noise itself, kinda hard to determine without hearing it in person.

 

[ChvyKc]

I made marks on the pulley like Defiant suggested and it still hasn't moved. I think that I am going to pull it off completely and inspect it while I have the belts off to pull the AC compressor out.

 

[oldman]

I made marks on the pulley like Defiant suggested and it still hasn't moved. I think that I am going to pull it off completely and inspect it while I have the belts off to pull the AC compressor out.

Have a friend crank the car while you stare at the pulley. If the pulley is defective or on its way out, it should wobble especially during start up.

 

[ChvyKc]

Have a friend crank the car while you stare at the pulley. If the pulley is defective or on its way out, it should wobble especially during start up.

Alright, will do. To tell you the truth, I was trying to figure out another noise the other day when my dad was trying to start the car while I was figuring out what was wrong with it. If he reved the car up, right before it revs back down to idle it will make a rattling noise. I thought that it was being caused by the alternator missing the bolt that hold tention on the belt, but it might be the crank pulley moving. I will definatley look into it.

 

[ChvyKc]

I took some photos of the crack in the turbo, I just wanted to make sure that you guys thought that it would be ok to run. If I got to get a new turbine housing then I would rather go ahead and get one. Thanks for all the help.

The first two show the crack going down from the manifold flange into the wastegate flapper and the last one shows the other side of the wastegate flapper.

 

[oldman]

I don't like the crack on the inlet flange, the flapper area crack isn't too bad. If you're keeping the turbo for good, get a new housing. If the big 16g is just a stepping stone, put this one back in.

 

[ChvyKc]

I don't like the crack on the inlet flange, the flapper area crack isn't too bad. If you're keeping the turbo for good, get a new housing. If the big 16g is just a stepping stone, put this one back in.

I plan on running the turbo for a while. I plan on keeping it stock appearing for a while so the turbo has to last. It will probably be on there for at least another year and a half to two years.