Just wondering if anyone knows about how much fuel a stock 5.9 cummins motor will consume just idling per hour. I know a semi low idling doesn't consume very much so a 5.9 shouldn't consume half of that.

 

We always figured the big trucks ate right @ 1gal/hr, so your 1/2 that estimate is probably close. If you should be needing to idle long, it would probably be best to have some sort of throttle control to step up the idle to about 1k rpm. I was reading somewheres on the Cummins or Holset website about prolonged idling at low speed(less than 1k) could allow engine oil pressure in the turbo center cartridge to overcome low boost pressure and possibly cause oil to accumulate in the turbo. You'd be billowing a cloud of blue smoke for awhile when you took off!! The higher idle speed raises the boost pressure to prevent help this, plus it warms the motor(always a good diesel thing) and better circulates the coolant for cab heat. Vicey-versey, it would cycle the a/c better and cause more airflow thru the radiator. Just my $1.53 !!

 

I believe the high idle is to help prevent the cylinders from washing down with unburnt fuel due to the prolonged low combustion temps at idle not burning all the fuel. Thats just what I remember though, I very well could be wrong.

 

Prolonged no load idle is not recommended for the very reason stated directly above.

 

[QUOTE=92DuallyCTD;1595273] I was reading somewheres on the Cummins or Holset website about prolonged idling at low speed(less than 1k) could allow engine oil pressure in the turbo center cartridge to overcome low boost pressure and possibly cause oil to accumulate in the turbo.

Tru, prolonged idling under 1100rpms does cause accumulation at the turbo and can also cause leakage from the tubine seals. Also, you should idle(about 1100rpms) for a few minutes after a good load to cool the turbo after heating it up or your shutting it down with hot oil sitting in there. If you can and you have the time, get it down to about 350 degrees at the pyro before shutting it down.

 

put your truck in neutral and set the parking brake and block a wheel. 727's and 518's circlulate in all gears including neutral, not in park, its hard on the torque converter and could possibly boil the fluid if its not circulating.

 

I had an alternator lock up on me in the middle of the night. Spent 4 hours idling in a NAPA parking lot for cab heat, and got the same MPG for that tank as the rest of the trip. I would say they dont use very much fuel. It takes more fuel to start than to run for 5-10min.

Daniel

 

best idea if your gonna sleep in the truck or let it idle a long time would be to set something on the pedal to let it rev up some? seems like it would be a good idea. i think mine idles close to 1000 now, i might just have to do that from now on when im on a long trip and want to sleep, i hate shutting my truck down if i dont have too, especially really far from home. ill just pop it into neutral, set the brake, block the wheels, block the pedal and let it idle while i sleep.

 

Hand throttles are a must at -40*. At those temps I won't shut down unless It's going to be for more than 2 hours. I keep the idle set at 1100-1200rpm.

 

So then we can say it's perfectly safe to let them idle for a couple hours IF you increase the idle to around 1100?

 

I say yes Dan, I got trapped in an ice storm with my Wife and Daughter so I pulled into a truck stop and decided to sleep there till morning, I cracked the drivers side vent window, turned on the heat, and placed my boot on the skinny pedal. The boot raised it just enough

Morning came and drove home safe and sound, I was there for 7 hours and my fuel mileage dropped about 1/4 mile to the gallon, so I think 7 hours of idle in order to be safe was a good call.

Michael

P.S. I will now put in neutral, I never thought about that.

 

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