legacycentral bbs

I'll be up front. I'm unsure what people mean when they say a turbo either does or doesn't have shaft play. I'm pretty sure I know but I wan to confirm that I'm right. My thinking is that when a turbo has shaft play it means that if you grab the exhaust turbine wheel and wiggle it, it moves. This means that the bearings are no longer perfectly round or have worn significantly and will develop snags in the futrure and seize up.

Is this correct?

I apologize for my ignorance but I want to be sure as I'm looking at a turbo and I can wiggle the exhaust turbine wheel. There's also a mild clicking noise.

You have the right idea.

There are two types of play to check for: axial and radial. You check for axial play by trying to push the shaft in and out (along its axis). You check for radial play by trying to wiggle the shaft side to side. You can use a dial indicator gauge to quantify the play.

Play indicates how much wear there is on the bearings. A little bit of play on an older turbo is not uncommon -- I bet most of us would find our turbos have a little bit of play if we checked -- and doesn't necessarily mean the turbo's about to kick the bucket. But yes, you're correct that excessive play can allow one of the wheels to contact its housing, and that contact will almost certainly cause the turbo to seize up as the friction is so great.

There's a bit of a catch, though. You're supposed to measure shaft play while supplying the bearing with pressurized oil. In many cases you'll find that you can move the shaft of a dry turbo, but after even just dripping a little oil into the cartridge that play disappears.

Just to add to what Vikash said.

The turbo I got from Dave had HUGE amounts of shaft play. The turbine & compressor blades both had contacted the housings. When I took it apart, the shaft itself had a wear spot in it. This went beyond bearings, which are typically the softer metal.