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

[candersen10]

My family farm has a bunch of tractors/skid steers and a lot of different people use the equipment. Some of us have gotten use to shutting machines down with the throttle all the way up. I've always assumed this is not good for equipment. Can anyone here articulate why it is not good to shut a diesel tractor down at full throttle, or if I am wrong, why it doesn't matter? Most of our machines are turbocharged and I have read that shutting a turbocharger down at full throttle causes it to spin rapidly without lubrication.

Has anyone had any turbocharger failures or other engine failures after regular full throttle shut downs?

 

[whis]

if pulling a load a diesel needs to cool a little bit be for turning of. question why would you shut one down this way? if it was my stuff and I caught someone doing that it would be last time they were on it

 

[Underdog57]

if pulling a load a diesel needs to cool a little bit be for turning of. question why would you shut one down this way? if it was my stuff and I caught someone doing that it would be last time they were on it

I agree, let her settle down a bit before shutdown!!!

 

[SPYDERLK]

You are talking hi idle as opposed to full throttle. Full throttle occurs only under full load where the gov gives full fuel. ... And yes, in that situation there is a lot of heat and very hi turborpm. Stalls during hard work are not good and should be restarted immediately. Intentional cutoffs under these conditiions are almost non existent. OTOH, cutoff from hi idle is not optimum -- but not so bad because it is a lo fuel/moderate heat condition. Best to go to lo idle tho, for a short period before shutdown.
larry

 

[whistlepig]

No different than a car or a truck. We don't shut them off or start them at full throttle.

 

[buickanddeere]

If it has a turbo and is shutdown from high idle. There will be shortened service life.
Have you asked the operators how they get their jollies from a max rpm shutdown? Obviously they have not read the operator's manual.

 

[Recoveryhill]

Shutting an engine down at full throttle defies any logical concept of good practice. Why would anyone do this? "Some of us"... I can't even imagine what thinking would lead to this with one person, much less "us". Out of kindness I allow any internal combustion engine to ramp down prior to shut off. This includes 22,000HP General Electric Gas Turbines, whose shutdown cycle is computer controlled. Balancing Delta T's is important on shutdown for any mechanism with dissimilar metals operating under elevated temperatures.

Other than this post, I'm speechless at the practice. Don't do it.

 

[k0ua]

Like the others I can't figure out why anyone would ever shut any engine down from high throttle speeds. It is counter intuitive. You say people are really doing this?

 

[Zebrafive]

In addition to not shutting down at full throttle, give it time to cool down at low idle, especially if it has just been worked hard. OM for my JD 6415 states two minutes idle for cool down prior to shutdown.

 

[whistlepig]

We just bought a new zero turn with a gasoline motor. My wife said it was getting hard to cold start. Right after that I saw her shut the motor off on it at full throttle. I told her to idle it down before shutting it down. It cold starts perfectly now.

 

[LazyHRanch]

A motor liquid or air cooled gets the hottest the minute it is cut off. It stops bringing in cold air. If you are at full throttle that heat is being dissipated in part by air coming through the intake when you stop bringing in that air and stop the cooling process without throttle down to help the engine release the heat you decrease the life of the engine by making it sit there and absorb all that heat. Also if you cut the motor off and suddenly stop the crank shaft while spinning at a high rpm it will remove a small area of bearing surface. One much larger than if stopped at a low rpm. Think about coming to a complete stop from 5 mph in your car or 60 to a complete stop in one foot.

 

[GManBart]

Pretty much the entire engine is designed to work with the loads in the opposite direction than what happens when you shut down at high idle.

One of the worst things you can do to anything with a timing chain, or timing gear, is shut it off with the engine at high rpm....friction wants to stop the pistons, but everything else wants to keep going (relatively far less friction) and that's how you throw a timing chain, or strip a gear.

If you've been running the engine at a normal work load for a while, and suddenly shut down, the other thing that happens is that the coolant stops circulating, and the excess heat has nowhere to go, so it dramatically raises engine internal temperatures.

Giving the system just a little time to stabilize under low idle before shutdown will avoid all of these, and probably other, problems.

 

[Happy Gilmore]

Strange question, not trying to sound rude, just a why ask why type of question.

 

[OldMcDonald]

Good question Happy. I have always treated machines like horses - walk the last mile home, do not gallop. In an emergency make sure somebody else cools off the horse.

 

[redman135]

If it was my gear the offender would get a swarm of wasps in their ear. Why should they wreck my gear? Also even if it was not my gear I would have a blunt word with them. That sort of machine abuse is very unprofessional.

 

[paulharvey]

I do agree with what's been said but, in construction, you see it a lot. Guy jumps on roller, revs it to max, uses it for 5 minutes; cuts it off. Mostly out of not knowing better, some from not caring. I've always heard to idle it down, and wait 10 seconds; no idea if that's a good about of time or not.

 

[candersen10]

Can anyone point to actual failures that appear to relate to frequent shutdowns at full throttle/high idle (i.e. the engine going from about 3000 RPM with the hand throttle full forward)? What fails specifically? Turbochargers?

Thanks for all the replies.

 

[candersen10]

Strange question, not trying to sound rude, just a why ask why type of question.

Not quite sure what you mean by this. I'd just like to be able to say, here is why no one should be doing this, and if we continue to do so, these problems will likely crop up.

 

[Recoveryhill]

Not quite sure what you mean by this. I'd just like to be able to say, here is why no one should be doing this, and if we continue to do so, these problems will likely crop up.

With all due respect, perhaps you should read all the good and valuable comments on why not to do this, in response to your Thread. You are asking why you should climb down a ladder instead of jumping off the top rung because it's a quicker way to arrive at the bottom. Personally I think you are smarter than that.

 

[chopped]

I think its a good question. However I think it addresses another subject of habits. Habits are hard to change but I think the poster is asking if it doesnt cause harm than why question why its done.
I view it part as similiar to why I leave the bucket on the ground when not running it. But Ive learned from here that it is good for the seals to be in pressure. So there are many factors involved.I still prefere to leave my hydraulics in a 'relaxed' state.
An example is lawn mowers of today ,they start on a high RPM I believe this is detrimental. But its how it is.Even my ride on ,to choke it you have to go through the throttle. and it chokes and starts on high RPM untill i can get the throttle back down to idle.
So i would guess in the long run if no turbo, it wouldnt be an issue which would be dependant on how many time and how many years.