Turbo Shaft? and play ?
04-26-2010, 02:52 PM
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Turbo Shaft? and play ?
I know I've heard a few times that play in the turbo shaft is an indication of a turbo headed south. Can someone explain where exactly the shaft is and how I can check for shaft play. Any help is greatly appreciated.
04-26-2010, 07:09 PM
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pop off your intake from the front of the turbo. your compressor wheel will be sitting there on a shaft. Give it a wiggle up and down, left and right, forward and back. make sure that the compressor wheel cant touch the housing at any of the extremes. you could use a dial indicator to measure end play but its usually a matter of 'yup, feels fine.' there will be a little bit of play so dont get concerned when it wobbles around a bit.
04-26-2010, 11:06 PM
#4
That's correct. Up and down, left to right slop is ok as long as the wheel does not rub the housing. End play or in and out is not acceptable.
The turbo shaft has floating journal bearings. These are bushings with an oil film between the bearing and the shaft and also between the bearing and the housing. So you may feel quite a bit of play as there is no oil pressure at rest to keep the shaft centered.
End play is a sign of a bad thrust bearing and may indicate a need to overhaul the turbo.
As long as the turbo is not run without oil or the engine is not shut down hot without allowing the turbo to cool say after a load or hard pull then the turbo should last a long time, say several hundred thousand miles or more. 500,000+ miles on a semi is common.
Some other things. Surging or barking may or may not hurt it and foriegn object entry will destroy the compressor or turbine wheels. Ultra high EGT can melt the turbine wheel too.
The turbo shaft has floating journal bearings. These are bushings with an oil film between the bearing and the shaft and also between the bearing and the housing. So you may feel quite a bit of play as there is no oil pressure at rest to keep the shaft centered.
End play is a sign of a bad thrust bearing and may indicate a need to overhaul the turbo.
As long as the turbo is not run without oil or the engine is not shut down hot without allowing the turbo to cool say after a load or hard pull then the turbo should last a long time, say several hundred thousand miles or more. 500,000+ miles on a semi is common.
Some other things. Surging or barking may or may not hurt it and foriegn object entry will destroy the compressor or turbine wheels. Ultra high EGT can melt the turbine wheel too.
04-26-2010, 11:09 PM
#5
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Seen many a cummins with more than 500k on the original turbo. Ive had semis make 1 million on a turbo. They will last a long time if you pay just a tiny bit of attention to them.
Carey
Carey
04-26-2010, 11:29 PM
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Thanks guys for all the responses. All the explanations helped greatly. Truck has been lacking power and wanted to rule the turbo out. Turbo appears to be fine. Checked for boot leaks as best as I could but didn't have any luck. Maybe a boost leak I'm not seeing or clogged cat? Or tranny? Truck really struggles going up large hills.
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