Turbo question

[Dvldog8793]

Howdy
We are upgrading my sons 1993 to a GM-8.
The turbo we have worked great when it was in service several years ago. It was a new factory GM-8 in 2003 with about 150k miles on it
It still spins fine, I can feel no rough spots, Cold blades look good....BUT it does have a small amount of end play.
I am seeing four different options:
- Have the whole unit rebuilt locally for 300-400$
- Order a rebuild "kit" and do it ourselves for 60-100$
- Order a "cartridge" and install that for 150-220$
- "Run what you brung" and just put it in as is for 0$
Opinions on what the best route would be?

Thanks!!!!

[DmaxMaverick]

It depends on what you mean by "small amount of end play". Most of them have some end play. If it spins freely, doesn't contact the housing at any point, and still spools well, it is probably good. If it ain't broke, don't fix it.

[Robyn]

OPTIONS OPTIONS OPTIONS

:D
A slight end play is normal.

Radial movement of the blades should be near ZIP

Look for any signs that the blades have contacted the housing, both on the compressor side and the turbine side.

Check the turbine blades for any nicks or damage.

These are a bronze bushing carried unit and are very durable.

Remove the hot side and cold side housings to allow a good cleaning.

Remove all carbon and crud from the blades.

Don't be afraid to wash the hell out of the thing.

Spray the oil port full of GUNK as well as the entire unit, then wash it in hot water.
Really flush out the oil port/bearing area well.

A double dose of GUNK and hot water is a good thing.

Blow dry with air with attention to drying the bearing area well.

No real need to disassemble the turbine and compressor wheels from the assembly as long as they are in good order.

**** Before cleaning****
Take note of any signs of oil leaking from the bearing area into either the exhaust or compressor side. Any leaks are an indication of a bad seal or ???

Once things are dry, add some oil into the oil feed hole and rotate the unit to work it in well.

Oil the bearing again just before you fire things up so it has lube for the first few seconds.

All clean and ready to go. COST, the cost of a can of GUNK and a bit of time.

A few years ago I tore the GM4 apart completely that was on the 94 Burb.

The engine blew a head gasket and coughed out a lot of antifreeze into the exhaust.

After sitting while I rebuilt the engine the carbon that was in the turbo "Swelled up" due to the antifreeze ???? and the turbo would not turn easily.

After a complete dutch scrub it was perfect.

Put it back together and it worked sweeeeet.

*****
The seals on these are a little end locking type ring that sort of looks like a tiny piston ring.
*****
These sit in a groove in the shaft and ride in the housing on both sides of the bronze bearing.

While you are in there, be sure that there is not a build up of crud on the outlet side of the bearing where the oil drains back to the pan.

Normally there is not, butttttttttttt, it can happen, and a restricted oil return can lead to oil leaking past the seals.

The oil is line pressure on the top of the turbo and the oil that passes the bearing simply drains back to the pan.

If memory serves, there are actually 2 flange'd bushings in these with the oil flowing into the center between the two and then passing the bushings and draining out.

The end clearance you found is the difference between the overall stack up of the turbine and compressor as opposed to the distance between the two bushing flanges.

Have fun.

[Dvldog8793]

Howdy
Thanks for the input!
I talked to my local shop as well. He told informed me that the center shaft is a free floating assembly and relies on a certain amount "play". This is taken up with the oil pressure once it is running.
The play that ours has is pretty tight and not very much, I didn't put a dial on it but it seemed minimal but noticeable.
So me-thinks we will clean it up per Robyn and run it.
Thanks again...
5x5....OUT

[Robyn]

Actually these turbos are really forgiving.

As long as they have a good steady supply of oil and nothing hard blowing through the turbine they will run nearly forever.

I have seen a few fools in exhaust shops (And other places) blow a hole in the cross over pipe with a torch to install a weld bung for a EGT sender.

As soon as that slag hits the turbine that is spinning a bazillion RPM it's game over for things.

Good luck on the project. :)