Screeching noise mid-high rpms after build no belts on

[cf91tsi]

I put my engine back together, started it up, and there was a high pitch screeching noise above 3k rpm. It seems to be coming from the belt side of the motor. Took the alt. belt off and it was still there. My buddy right away said the compressor housing on the turbo is probably off a bit. This is the first time I've had this turbo (evo III) on the car, came from a salvage motor and look practically new. Also, almost certain the sound is coming from the case/rear sides of the motor. Would appreciate and useful thoughts. Oh ,91 awd, balance shafts removed, brand new mitsu oil pump with gears, mitsu shaft eliminator stub.

 

[rush2252]

uh oh. I hope you did your homework and rerouted the oil feed to the turbo FROM the head and not the oil filter adapter/stock location?

There is an allen head on the left front corner of the head. Remove it and run your oil feed line from there. When you remove the BS if done correctly you will increase oil PSI significantly and can kill a turbo in just a few seconds.

Kolby

 

[Calan]

I put my engine back together, started it up, and there was a high pitch screeching noise above 3k rpm. It seems to be coming from the belt side of the motor. Took the alt. belt off and it was still there. My buddy right away said the compressor housing on the turbo is probably off a bit. This is the first time I've had this turbo (evo III) on the car, came from a salvage motor and look practically new. Also, almost certain the sound is coming from the case/rear sides of the motor. Would appreciate and useful thoughts. Oh ,91 awd, balance shafts removed, brand new mitsu oil pump with gears, mitsu shaft eliminator stub.

I'm a bit confused...where exactly is the sound coming from?

If it's in the timing cover area, I would guess that it's a tensioner or idler pulley, unless they are new. I've seen this exact same thing...screeching noise from the front cover with no belts, and it was one of those two. (Can't remember which one, but they were both worn).

Check the turbo for any axial shaft play. (a VERY SMALL amount of movement side-to-side is normal, but there should be none at all straight in and out.) Are you blowing any blue/white smoke, or is there oil in your IC pipe?

I'm thinking that if your compressor housing is "off a bit", it will only be that way for a few seconds of boost and then there won't be any doubt about it being the turbo

 

[cf91tsi]

The turbo is fed from the head- which is the stock location - I'll be putting a oil pressure gauge on soon to find out the actual oil pressure - the shafts were previously removed and this noise was not previously there...


Almost certain it is coming from the top end. Its a high pitched metal on metal type screech, variant with rpm. I pulled the T-belt, the tension/idle bearings seemed fine, they only have like 15k miles on them, so they shouldn't be bad. Also, I have yet to finish the shafts and struts, so it hasn't left my garage yet, so this is happening in neutral under vacuum, no boost. Also, this only started happening once I put everything back together. Things that changed were: new crank w/bearings, new mitsu oil pump, different 16g, tubular exh mani, and different valve cover.

I'll pull the valve cover tonight and look for anything suspicious. I just done see those bearings going bad while sitting off the car for a week, plus they seem solid with no abnormal movement?

Was also thinking of just throwing the wheels back on and taking it for a spin to see how it reacts to that.

 

[turboedspyder]

i just had that screeching noise happen to me after startin it after a whole rebuild, and it was the turbo... now good.

 

[Calan]

Was also thinking of just throwing the wheels back on and taking it for a spin to see how it reacts to that.

Probably not a good idea. If there is a serious problem, putting a load on it may end up causing a lot bigger problem than the current screech. I'd exhaust all possibilities to find it first.

How about that turbo? Did you check for shaft play?

 

[cf91tsi]

i just had that screeching noise happen to me after startin it after a whole rebuild, and it was the turbo... now good.

What was wrong with the turbo? did you fix it or replace it?

and the turbo has a little side to side and no in and out play, which from what I understand and have read elsewhere is normal. And no smoke, but as I said, I haven't driven it, which is usually when you'll see smoke unless the turbo is totally toasted. Even though it doesn't seem like its coming from the turbo (louder near ignition pack) Im thinking it is echoing and gonna just empty all the fluids again and pull the turbo.

And thanks for the feedback guys

 

[Calan]

Do you have a mechanics stethoscope? You can pick one up cheap at a parts store and they are pretty helpful for isolating sounds.

Still doesn't sound like the turbo to me, but anything's possible.

 

[turboedspyder]

idk what happened or even how it happened. maybe it was because of the increased il pressure from deleting the balance shafts? i dont even know. it was random. i coulda rebuilt it ###### but i just ordered a ported evo316g for only 600 shipped so i guess it wasnt too bad

 

[tsiAWD91x]

i had a persons car i was working on 2nd gen GST have the same type of problem loud screeching sounded like a bad belt rpm dependant (same as you bud) except it was the throwout bearing in the tranny and the noice i swear came from the front of the motor (belt side) and it was loud as hell coming from underneath the car... like the other guy said sounds can be tricky in my case is a perfect example... just somthing to think about... but again im not there to hear exactly what your talking about