I have an '89 740T, automatic, A/C,about 156K miles with a Garrett (I think a T3) water cooled turbo.

About a week ago, the car started making a noise very much like the turbo impeller blades hitting the shell- a "zing" when the boost climbs. I checked the stock boost guage, and noticed that the zing happens at about 11:00 needle position. I took my car the mechanic, and he told me that the turbo is going, but I could drive carefully for another month- doable, since I work from home and live in a small town, and most of my driving is in town. I can drive around without the need for boost. so I pulled the inlet pipe to check for end play, and there was very little wiggle- certainly not 1/16", barely enough to even move it side to side. Other things to mention are a possible front seal failure- a minor oil leak, and the flame trap has been cleaned, blows freely, but never replaced. The rubber hoses are in good shape, BTW.

So I am wondering if I have a misdiagnosis.I am considering a DIY job, so I want to make certain that this is the problem before I go ahead and order a turbo and gaskets, etc.

I have a few subsequent questions also: assuming the turbo is bad and it is "zinging", is it allowable as an exchange for a factory rebuilt one? Anyone have an east coast recommendation for a supplier? I would like to go to a T3 /T4, and I would like to hear comments on that. Do I need to replace the oil inlet pipe, as well? One oddity is that I noticed there are no turbo to exhaust manifold nuts on my car- just the studs sticking out. Is this stock?

Thanks in advance

RLedbetter