Let it Idle, or Shut 'er Down?

[centex]

Re: Let it Idle, or Shut \'er Down?

I let mine "idle" at half speed which is the speed the JD recommends for warmup. Starting up an engine several times a day means it has to warm up several times a day and that is not good for it. I asked the service manager at my dealer if I should change my oil more often than the 200 hours recommended in the service manual. He said if I shut it down several times a day I should change the oil more often but if I just let it run continuously I should stay with the recommended interval. I don't let it idle at idle speed for long periods of time but at 1200 rpm and above the temperature stays up. I hope it is ok to run it at that speed because I ran it there for about 200 hours (not continuous) while digging post holes with a 3PT PHD which is supposed to be run just above idle and not over 300 RPM at the PTO which is 1500 RPM on my tractor.

 

[art]

Re: Let it Idle, or Shut \'er Down?

For thirty minutes on a warm tractor I'd be shutting it down.

 

[bigpete]

Re: Let it Idle, or Shut \'er Down?

<font color="blue"> I hope it is ok to run it at that speed because I ran it there for about 200 hours (not continuous) while digging post holes with a 3PT PHD which is supposed to be run just above idle and not over 300 RPM at the PTO which is 1500 RPM on my tractor.
</font>

That sounds like the kind of work your engine will love. The big difference between those hours and hours at idle is that you were varying the load while you were digging post holes.

 

[5030]

Re: Let it Idle, or Shut \'er Down?

RWest:

I didn't read the whole thread so this might be repetitious or it may not be. As a rule of thumb............

If a diesel engine or gas engine is naturally aspirated (not turbocharged) You can shut it down almost immediately after use.

If the engine is turbocharged, inter cooled or after cooled, you should idle the engine to allow the bearings in the turbocharger to cool down and the internal temperature to stabilize. A pyrometer reading of 300 degrees Fahrenheit is a good shutdown point. Shutting down a hot turbo will cause the oil in the bearing cavity to overheat and "coke". That will lead to eventual bearing failure. This applies to diesel pickup trucks as well. (Dave) /forums/images/graemlins/shocked.gif

If you are working your tractor under heavy load conditions whether it's turbocharged or naturally aspirated, it's a good idea to allow a short cool down period and allow the internal temperatures to stabilize.

 

[yellowsocks93]

Re: Let it Idle, or Shut \'er Down?

One thing no one has mentioned yet: In the manual for my 990 it says not to idle the tractor for long periods of time while it is in break in for the first 50 hrs. They should give a time interval like 15 min or 30 min is too long.

 

[Docsknotinn]

Re: Let it Idle, or Shut \'er Down?

So Im watching a movie tonight and I feel this little jab in my side....I knew you were up to something. Trying to slip one in on the side /forums/images/graemlins/shocked.gif I'm trying to kill the Duramax now any how. Someone PLEASE tell me why I bought a truck with a Isuzu engine in it /forums/images/graemlins/confused.gif /forums/images/graemlins/mad.gif /forums/images/graemlins/crazy.gif Now on my itty bitty wannna be toy tractor I let it idle for 10 -15 minutes max. More than that I shut er down.

 

[JClark]

Re: Let it Idle, or Shut \'er Down?

Back in a previous life worked at a boatyard building large yachts. We used big, as in 12 cylinder big, Cummins diesels. The engine dealer would send a couple of guys to do the first startup which was apparently a big deal as it would take them most of the day to do 2 engines. One guy wore regular mechanics clothes but the other guy always wore a white shirt and tie. He would roll up his sleeves, climb down into the engine room and spend hours checking, measuring and whatever. All very impressive.

Now that we have established his credentials let me tell you what he says about long idling of diesel engines. Because of its high compression a diesel engine will bleed down a lot of fuel at idle and cause the lube oil to be diluted. This is aggravated by the low combustion temperatures at idle that cause a lot of fuel to go unburned. The low temps also cause deposits from incompletely burned fuel. So let the engine idle long enough to cool the turbos, pistons and valves and then shut it down. A minute or two is enough. One of the reasons diesels carry so much lube oil is the fuel dilution problem.

FWIW

 

[5030]

Re: Let it Idle, or Shut \'er Down?

JClark:

I didn't know that a Cummapart had much compression??

I always considered them to be a good boat anchor. Maybe that's why they were in a boat in the first place.