Turbo

I often go around auto auctions, and rarely you can actually find a nice turbo there... I recently saw a '90 Eclipse GS Turbo, but got outbid (didn't wanna go past 900$)... the problem is, you obviousely can't test drive these, and you only see them running as they drive up and wait in line to be auctioned (roughly 3-5 mins)... then they pop the hood open for maybe 30 seconds before people start bidding.

Would anyone recommend some ways to check out a turbo on a car in this situation? I thought about asking the driver to just rev it up or something maybe...

btw, i found that the turbo was in fact broke on that eclipse a week later talking to the buyer, so he got fucked =)

How much could it cost to repair this sort of thing anyway?

Turbochargers usually cost around $800 if it's a normal turbo like a Garrett T3, T25, T2, MHI TD04 or similar. If it's bought in second hand (new) the prices are usually from around $250, if it's used they are a little cheaper.

There is really no way to check the car by just looking on it. To check the turbo itself you must look on the impeller and turbin to check for damages and hot corrosion (on the turbin). You must also check so there are no cracks on both wheels and houses. Then you must check the bearing clearences, the axial clearence should be so small that you can't feel it, the radial clearence shoul make it possible to move it maybe 0,2-0,7 (dependning on turbo, specially its size).