What part of the truck doesn't burn?

for years owners and mechanics would say truckers were to blame for turbo bearing failures in Cat crawlers because they didn't plug the exhaust while hauling the machine. the claim was that air moving over the exhaust while the engine was off caused turbo bearings to spin without lubrication causing them to burn up prematurely

turns out bearing failures were from operators not properly cooling down the engine before shutting them off. turbo bearings were still extremely hot, shutting down the engine too quickly after working under load would allow the superheated bearings to burn the oil left in them the moment the engine was turned off. they called it "coking" the bearings. the result of burning the oil left a residue as hard as sand and would quickly damage the bearings hard surfacing on the next startup.

but, the customer is always right....

 

That’s right magnesium even worse than aluminum, once it gets started, almost impossible to extinguish.

 

Oil coking occurs at 600 degrees, you would have to be working a tractor at full tilt for several minutes and shut it off with no idle time to coke the oil and damage the turbo; that is very rare unless you run out of fuel while pushing. But Turbos do spin dry when you haul equipment down the road without capping the exhaust, a short haul won't damage them but a long haul will; if you pull into a rest area and run back real fast you can hear the turbo still spinning on a hauled tractor without the exhaust capped.

 

no it doesn't. to turn the turbo, air has to go either through the intake, through the impeller, and out the exhaust, or into the exhaust, and out the intake. it cannot happen with enough force to spin the turbo at any speed. there may be a little valve overlap to allow a minute bit of air to pass, but certainly not enough to spin the turbo and cause bearing failure.

 

No way Jose !!is that means air would have to go all the way backwards threw the motor and back Out the air filter I just don’t see that happening fast enough to make the turbo spin !

 

if that's happening, there are bigger issues within the engine than turbo bearings.

 

That is not what happens, the air passing over the exhaust creates a vacuum that draws air and spins the turbo; there is never a time when all the valves are closed at the same time so air can be drawn very easily through the engine.

It also takes almost nothing to spin a turbo, you can flick a turbo impeller with your finger and it will spin for 30 seconds; any constant spinning without oil pressure will cause scouring of the bearings.

 

I guess that’s what happens out here in West Texas with the 60 mile an hour winds just sitting out there wearing out all the turbos on those tractors !!

 

I would encourage you to operate a heavy equipment lowbed any way you choose, I fully support people learning things the hard way.

 

lol...it's like a flat earth debate.