Garrett GT Turbo "screeching" sound

[BaliLover]

I had a major bearing failure on my old GT28RS and needless to say I was pissed. The turbo had been making an occasional high pitched spool/"screeching" sound when boosting at anything other than WOT for a short while. This was not a constant noise. Well, one day, the turbo goes from 15psi to 0psi in one nasty second. I remove the turbo and I've got an obviously spun bearing.

Upon closer inspection, no oil was getting thorugh the center section, its as if there was an internal blockage in the turbo that stopped oil flow. I tried to blow air through the oil passage on the dead turbo and there was no air flow whatso ever. Blocked solid. I use only mobile-1 15-50, Mobile 1 filters, I change oil every 3 months like clock work and I've never found any particles of metal in my oil. Oil pressure is solid at around 70psi when the car is warm and I'm crusing.

So this time I decided to upgrade to the GT2871r and while I was at it I replaced water lines, oil feed line and the oil drain line just to be sure there wasn't a problem. I installed the ATP restrictor on the new turbo to make sure that also wasn't why my GT28RS died. I changed oil again before restarting the car, I checked to make sure there was oil flow through the lines and out the drain flange, checked the water flow, etc. Everything checked out. I get the turbo installed, and it drives fine and doesn't make the screeching noise at non-WOT boost.

Flash forward to this week and the damn noise is starting to show itself. If I try to hold partial throttle boost at 15 psi, I get the noise. Needless to say, I've very pissed about having 2 GT series turbos, both purchased brand new, developing the same problem. At $1200 a piece, this is a bit rediculous. I don't know what more I could possibly do. I've installed the required restrictor, replaced lines, used top quality oil and filters, etc. The turbo intake is filtered and there are no tears in the filter, and there are no holes in the intake piping.

Has anyone else run into this problem or know what I can possibly check to see why its happening?

[kandyflip445]

Do you have a turbo timer?

[BaliLover]

Yep, I've had it before the 2 turbos.

[Campos]

ok, bout to install one of these myself, this may sound stupid but what is an atp restrictor????

[ultraDorksGarage]

What is the turbo centersection angle at(imaginary line from oil infeed inlet to oil discharge outlet is optimum at perpendicular to the ground)? i wouldnt let the clock lean off more than 10-12 degrees off perpendicular to the ground. ive been running my t3/t4 at about 10 degrees off perpendicular.

bad clocking was the source of my friends turbo gumming up, was caught early enough, and we ran chevron "delo 400" (beware though, turbo diesel type oil should only be run in our system for short periods of time) through it and it cleared out the gunk. low mount turbos suck><.

also, is the oil discharge outlet on the turbo too low, causing pooling of oil in centersection?
hope u figure this one out, gt types are expensive><

[ultraDorksGarage]

btw, 70psi during cruise rpm's seem high to me, i run 2.25-3 bar oil pressure, so i guess thats 33-45 psi, i dunno my math is bad><.

[BaliLover]

Both SRs I have had ran around 70psi oil pressure at 60mph. The only time I experienced 30psi at cruising speeds was when the first engines oil pump took a crap and I spun a rod bearing.

The turbo is clocked so that the drain flange is perpendicular with the ground, there is NO angle on it. The oil drain flange is at the stock height and position so I don't think thats an issue.

[mbmbmb23]

Did you take off the lines again and try and blow them out again? (with the 2871) Is that oil you are using synthetic? In what condition is your oil pan/pickup?

-m

[BaliLover]

Both the oil feed and return line are new, as is the coolant line. The oilpan is a Greddy pan, the pickup is fine since this motor came with an undamaged OEM pan. Yes, I'm using mobile1 syn. oil and have been as long as I've had the motor.

[ultraDorksGarage]

hmmm, how about EGT, are they too high from too much timing retard or lean fuel mixture? the turbo diesels i deal with lose turbo bearings when the diesel fuel pump/mechanical injectors give trouble. EGT goes through the roof and we fry stuff.
although our turbo diesels dont have water cooling, which would prob. keep turbo alive way past your valves in that case.
what about major blowby? if i recall our motors return line is into the casing right about the pan(0 pressure), crankcase pressure rising not allowing oil to properely flow through centersection?

Good luck

[rabid_monkey]

vosko's GT25R was making almost a supercharger noise for like 6 months and we were all like wtfmate. turns out his manifold had a hairline crack, check for cracks anywhere just to be sure. i think his new turbo and manifold makes the noise too tho, so i dunno, just giving you another idea.