Tractor turbo- Ruined bearings

[av8r]

I am in the midst of a debate on another website concerning turbos on tractors and other heavy equipment. :-{}



The debate is about how if the exhaust stack points forward, it must be covered while trailering the unit or the air blowing into the stack will spin the turbo and ruin the turbo bearings. :{



To me this sounded logical on the surface, but when I started to think about it, the logic went away. For the turbo to spin, the air must move through the housing at enough velocity and volume to turn the turbine and compressor (backward) and overcome the drag of the (frying) bearings. For this to happen, the air must have someplace to go when it leaves the turbo, right? Through the motor and out the intake is the logical answer. BUT, don't those pesky valves get in the way? Is there that much overlap in the cam grind to allow the intake AND exhaust valves to be open (wide enough) to allow that kind of flow? I think this is a myth. One of those "... my brother's buddy's neighbor knew this guy that... " or am I wrong?



I defer to the knowledge of the diesel gods here at the TDR to help me end my mental suffering.

 

[lmills]

I have always heard it also. If you think about it the turbo can spin without producing boost. So, I guess it might be possible to damage one that way. I am intersted in some input on this also.

 

[bmoeller]

There is a thing called valve overlap. It is possible, that if it spins at all, even at low speed, damage is possible on a long trip, from the lack of lube.

 

[nickleinonen]

There is a thing called valve overlap. It is possible, that if it spins at all, even at low speed, damage is possible on a long trip, from the lack of lube.

very true. the valve overlap is the ticket... you need to cap the intake or the exhaust to prevent the charger spinning while being towed even if the stack faces away from the direction of towing, speeds get high enough, you can create a low pressure area right at the stack, and low pressure will cause the charger to start to turn from flow from the intake side

 

[Cigar John]

I've hauled new tractors and backhoes dealer to dealer and no one has ever mentioned this to me.

 

[fox]

It can then be said that if you have it slash cut to the rear it will draw a vacuum and pull air the other way.



The only safe way to haul a turbo tractor is with the turbo on the seat next to you ???

Just funnin' ya.

 

[MMiller]

I myself have never had it happen, heck I don't even know anybody that has had it happen to them, but when I used to pick up new John Deere combines at the factory in Moline, they would wire the rain caps shut. I have seen many heavy equipment transporters, and most cover the stacks.



This being said, I cover the stacks on turbo'd engines. Its cheep insurance.



On a side note, a diesel sounds real cool when you start it and have forgotten about the duct tape on the stack!! Scares the crap out of you at first! Then embarrasment sets in that you forgot to uncover the stack!



Michael