What happens if you regularly shutdown a diesel engine with the throttle wide open?

[SSdoxie]

I haven't read through all 50 some posts but answer this question with some good detail, based on close to 30 years in equipment service.

Regarding turbo: The turbo receives a constant supply of cooled oil from oil pump when running. The turbo is power by the exhaust so it is extremely hot when under full RPM. There is a drain orifice in the lube line going back t tank to keep sufficient oil around the turbo shaft/bearing while engine is running. When you shut off the engine at full RPM before idling an letting temps stabilize that oil setting around the bearing stops flowing, absorbs the heat from the turbo and starts to overheat oil creating a carbon build up on the shaft & inside the bearing. This is referred to as "coking", that carbon does not burn off with next engine run so eventually wears on the shaft & bearing causing turbo failure.

Second possible failure: Head gasket &/or cylinder head cracks. Engine is hot and when shut off coolant stops flowing. The coolant around the cylinders absorbs heat from the cylinders (which are much hotter than boiling point of the coolant) and coolant has now where to move to displace the heat. Heat rises so all this heat goes to the head. Cylinder head has to expand, possibly stretching head bolts beyond designed limits or worse, cracking the cylinder head.

Third problem: If throttle is left at wide open and engine is restarted. Engine starts and goes to full throttle immediately before it ahs a chance to build any oil pressure. While the oil residue in bearings offer some lube, if this is done habitually over a length of time and numerous start ups it will cause extra wear on internal bearings and rings.

Throttle down after a hard run and let it cool for a minute or 2.

 

[Happy Gilmore]

Candersen10, how goes the battle? Any luck?

 

[farmer2009]

The sticker on the spray coupe reads like this. Before shutting down engine. Allow engine to run between 1000 & 1400RPM's for 2-5 min. To avoid turbo failure. Shoulds like they may have done some testing.
I always throttle back on the way to the barn then letit idle for a few seconds before shutting off. If I bogg out the motor then I will bring throttle back to idle before staring back. Just the way I was tought.

 

[farmer2009]

The sticker on the spray coupe reads like this. Before shutting down engine. Allow engine to run between 1000 & 1400RPM's for 2-5 min. To avoid turbo failure. Shoulds like they may have done some testing.
I always throttle back on the way to the barn then letit idle for a few seconds before shutting off. If I bogg out the motor then I will bring throttle back to idle before staring back. Just the way I was tought.

 

[DB Pilot]

I got caught by surprise when my better half did a high RPM shut down when I asked her to turn the tractor off out in the field. :shocked: I can only attribute this to a lack of experience in using tractors. Best analogy I could give to quell an argument I could see coming is ... When you shut the car off notice that your foot is not on the pedal or throttle causing the car to throttle itself down. :thumbsup: With the tractor we have to do this manually. :laughing:

 

[k0ua]

I got caught by surprise when my better half did a high RPM shut down when I asked her to turn the tractor off out in the field. :shocked: I can only attribute this to a lack of experience in using tractors. Best analogy I could give to quell an argument I could see coming is ... When you shut the car off notice that your foot is not on the pedal or throttle causing the car to throttle itself down. :thumbsup: With the tractor we have to do this manually. :laughing:

Good Thinking DB:thumbsup:

 

[ctgoldwing]

If it's not pressure lubricated, then it's splash lubricated....so while the crankshaft is spinning, oil is being distributed.

We have a of diesel gensets in the rental fleet, from 25KW up to 225KW, and all of the newer ones have controllers from companies like Deep Sea. The genset manufacturers have these controllers configured in a variety of ways to shut the machines down in the event of low oil pressure, high temperature, low or high voltage output or frequency, etc. One other thing they often program into the controller to shut the gensets down, is a service-minder. If it's programmed to shut the unit down at, say 250 hours to let the operator know it's due for service....then it does so. They just shut off. They can be immediately re-started, (which is what the operators always do), and then they run for another 10 hours or so....and shut down again.

After doing this at least a couple of times, the customer calls and we either tell them how to reset the service timer, or we go out and do it ourselves.

Total "damage" thus far due to the shutdowns during operation? Nothing.

Total "damage" done thus far due to a customer renting too much machine for their job and not working it anywhere near as hard as it should be working? Well, that's another story altogether.

Not "advocating" full-throttle shutdowns, but I will take 'em over wet-stacking.

This thread has been pretty much beat to death but while it still has some life left in those abused bearings I'll add my 2 cents.

Three years ago my son & I bid on & bought army surplus generators out of Ft Meade in MD. They were MEP-003A units - 10 kw diesels. They have 4 cyl air cooled Onan motors in them and are known for their toughness and longevity. The 'recommended' method of starting & stopping them is at full throttle (1800 rpm). There are numerous threads over Steel Soldiers, http://www.steelsoldiers.com/forumdisplay.php?55-Auxiliary-Equipment, that profess this is the only way to operate this type of genset - and they are really **** about it.

Of course no one recommends starting or stopping them with a load attached. I believe 5000 hours is what the army says they should be rebuilt at. Tough lil mothers.

 

[TomSeller]

We use this transplanter (Water Wheel Transplanter Farming Equipment :: Rain-Flo Model 1600). It is only a ground speed issue, as people sit on the back to transplant seedlings from trays into the ground.

If you have people manually transplanting, they can adjust to variations in ground speed during starting and stopping. I assume they are needing to start and stop to refresh trays, get to the end of row, etc? Earlier I had thought you must have a mechanical transplanter with its own fixed transplant speed and the tractor had to match that speed and they did not want jam up things so they shut both down at the same time, etc. My transplanters are ground speed driven so it did not make sense. I think your people are either lazy or just don't understand. I wouldn't think the tractor would be shut down until end of shift or when refueling, etc.

 

[DarkBlack]

I think the question needs to define if the condition is/was engine at full load, or just at full RPM. Totally different situations.
While I would cringe at a full RPM shutdown ( not overly hot and loaded ), I can't think of any real wear it would cause. Full load would be different.
The oil pump and water pump speed are proportional to the engine speed.
I think the OP has a good question.

 

[DarkBlack]

Some people do just that...blip the throttle just before turning off the key. I've seen a famous British race car driver do that over and over on one of those shows where they drive famous vintage race cars....he's shutting down a multi-million dollar Ferrari and blips the throttle before shutdown. Guess he doesn't realize it has like four timing chains (prior to all gears) that can skip a tooth doing that (inertia of the chain wants to keep it going when the cams and crank stop) and possible cause valve/piston contact....just stupid.

Say what...? I didn't know chains had inertia, but cams and cranks didn't.