GM-8 Turbo Play

[knh208]

When I replaced my injectors a few weeks ago, I started checking my turbo for play to see what condition it is in. I was able to check more closely today with a better set of feeler gages. There is very little axial play, but a decent amount of radial play. With shaft pushed away, I have 0.016" between the wheel and the housing. With the shaft held close, I have 0.0025" between the wheel and the housing . That tells me that I have 0.014" radial play (±0.007") and pretty tight clearance.

Does anyone know what the service limits are for the GM-X turbos? How do they measure when new? Should I be concerned? How close should I let this get? :???:

Obviously, I know that the worst case result of 0.000" clearance would be catastrophic failure of turbo and engine. The truck has 305,000 kms (189,000 miles) on it now. I plan on driving it until a major failure occurs. Given my recent tune up efforts, I hope that means for a couple years. I'm quite happy to enjoy my truck that is paid for, but at the same time, if spending a little is what it takes to keep it moving another year, so be it. :agreed:

Cheers,

Kevin :thumbsup:

 

[great white]

The only thing in my 98 FSM is to replace the turbo if the compressor contacts the housing when you rotate it by hand. It doesn't give a clearance.....

 

[WarWagon]

Recall the bearings have 2 elements in it aka a floating ring between the bearings. This allows quite a bit of side play that tightens up with oil. (oil from engine running and shaft speed.)

 

[knh208]

The only thing in my 98 FSM is to replace the turbo if the compressor contacts the housing when you rotate it by hand. It doesn't give a clearance.....

Well, contact is equal to zero clearance. I don't like the sound of that...

Recall the bearings have 2 elements in it aka a floating ring between the bearings. This allows quite a bit of side play that tightens up with oil. (oil from engine running and shaft speed.)

I assumed this is exactly what would happen when the oil started flowing. The shaft will generally rotate within the center of the bearings.

Does anyone else have measurements to compare? I love the idea of owning at ATT, but I love spending nothing on the truck even more. If it will keep running safely as is, I'll keep driving!

 

[JiFaire]

Recall the bearings have 2 elements in it aka a floating ring between the bearings. This allows quite a bit of side play that tightens up with oil. (oil from engine running and shaft speed.)

Yep, what He said ... when the thing is running, with the bearings full of oil pressure and gyro-stabilized, the vanes wouldn't contact the sides. Just keep an eye on them, every so often... if they start to get nicks, then you need to worry.

Until then, carry on!

 

[knh208]

Okay. I'll check it at oil change intervals. That should be often enough.

Cheers!