Idle or shut down?

[ray66v]

Originally Posted by Soundguy

Remember.. some trucks have idle up solenoids, as well as idle variance built in. also.. trucks with reefers have a seperate engine in the back for the compressor that kicks on automatically to maintain temp. At a distance.. a reefer running might sound like a truck idleing..

soundguy

I am aware of these. I am told the idle up on a semi is for heat in the winter. If thats the case it means its not a factor in the summer.

[ray66v]

Originally Posted by Egon

Then there are those who say the most engine wear occurs at start up?

I talked to my engineer friend today, and he said by far the most wear occurs in an engine during a cold start. Meaning engine has not been run prior to being started.

He is going up the chain with the idle question to some very competent diesel people.

I do wonder how many are idling now at $4.25/gal?

[RalphVa]

Here's some info to back up what daTeacha said: From Daily Fuel Economy Tip » Turn Your Car Into a Hybrid by Simply Turning it Off "So, when should you turn off your engine? Believe it or not, more than 10 seconds of idling uses more fuel than restarting your engine. As a rule of thumb, if youæ±*e going to stop for 10 seconds or more - except in traffic - turn off your engine."

A diesel engine has about double the compression ratio and will likely take about twice the electrical energy to restart it. Therefore, the time to run vs. shut down is about 20 seconds for a diesel.

I doubt that if your engine is fully warmed up that letting it idle is going to cause any fuel to condense and go into the crankcase. However, the cost of energy to run it vs. restart it is the overriding consideration. Safety, though, is another consideration. It's safer to shut it down and put Park brake on and leave in gear when dismounting the tractor. Therefore, when needing to dismount for more that 20 seconds, it's both fuel efficient and safer to shut it down.

By the way, I shut my car engines down at long traffic signals or if stopped for a long delay in traffic.

Ralph

[ray66v]

Shutting your car off in traffic, or at long lights may seem like a good idea. However, I submit that things like you starter and ignition switch are made to last so many thousand cycles. Then they crap out. If you end up spending hundreds to replace a starter that you finished off early, due to excessive use, how much did you save?

To me this is like down shifting to stop, spares the brake linings, but, puts extra wear on the more expensive clutch and pressure plate.

Todays cars are fuel injected and computer controlled, they run lean enough for me at idle.

[PAB_OH]

I never idle below 1600 RPM for extended periods. It allows EGT to fall and wet stacking to occur, from what I'm told. I will however "idle" at 1600 RPM for up to half an hour depending on what I'm doing (chopping wood and hauling back to the house, etc...). If I'm getting off the tractor and putting myslef in a position where I could be injured, I shut it down regardless.

My neighbor is a long haul driver. He almost never shuts his rig down. I know, I can hear it at the bottom of my hill ALL NIGHT LONG! I've never asked why but I'm assuming it's the "cold" start. With 80000 lb. GVW you probably don't want to lug it around on a cold engine.

[QRTRHRS]

Originally Posted by john_bud

You wrote in Word and pasted in format characters that goof up the works.


On idling, if it's so good, why do transport companies monitor idle time and reward the driver with the least amount? 'cuz it ain't so good to let them idle.

I'd bet you dollars to donuts that if you go to a truck stop tonight you won't hear the independents running their engines - they are paying for that burbling sound at $4.25 a gal! It didn't used to matter when fuel was $0.35 a gal, but now....

jb

Not to mention the anti idling laws with rediculous fines!

[QRTRHRS]

Originally Posted by PAB_OH

My neighbor is a long haul driver. He almost never shuts his rig down. I know, I can hear it at the bottom of my hill ALL NIGHT LONG! I've never asked why but I'm assuming it's the "cold" start. With 80000 lb. GVW you probably don't want to lug it around on a cold engine.

Just my personal opinion but what with most trucks having a block heater and/or the cost of one being so low, any driver parking at their home and not plugging in needs some therapy or something.

A lot of my tractor use envolves idleing. After a cold start, I let my tractor idle about a minute then idle it up to warm up perhaps a minute or more depending on just how cold it is. Then I will idle it up to perhaps a thousand or so RPM's to warm up some.

Just as with my Cummins powered Dodge, I stay light on the throttle until thoroughly warmed up. By the way, with the Dodge, if it has not been plugged in, I idle only about a minute before I lightly take off. Still no oil burning at over 200k.

Anyway, back to the tractor. If it is still cold when I need to idle, I fast idle it some. If it is warm and I expect to be off of the tractor for more than a minute or two or five, then I shut it off.

As a CDL driver, I have spent a bit of time sleeping in an ildling tractor, many with upwards of a million miles without a rebuild. I always use the cruise control to set the idle up to around 1,000-1,250 RPM's. Hopefully, you can find a "sweet spot" where the vibration is minimal.

[rutwad]

I don't have a specific idle or shutdown rule that I follow, I just do what seems right at the time. Idling for 30 minutes at 1600 RPM's, I don't do. Running a diesel hard and shutting down immediately, I don't do.

If I have been running hard, I will allow the diesel to idle a couple of minutes before shutting down, especially if it has a turbo. If I haven't been running hard, I may let it idle for a minute. These usually apply to ending my work.

I see no reason to idle for 5 minutes with intermentant stops, normally. But take my old backhoe for example. I may shut it down every time I get off for even a minute or two because of it's lack of good brakes and hydraulic leaks. Given the same situation for the Kubota, I would let it idle for a minute or two.

A diesel engine needs to warm up before operating under heavy load, and needs to cool down afterwards before shutting down. I would say anything over a couple of minutes, you should shut it down.

Diesel locomotives are to be shut down if idle time will exceed 15 minutes. The time limit may have been less, except they figure it will take approx. 5 minutes to crank it. On the other hand, they are not to be shut down within 30 minutes of operating at wide open throttle.

UPS wants their trucks shutdown at stops, but it may also be for safety.

[jdpharmd]

If you shut down often, would that not wear on all the mechanics of the starter/flywheel, etc.

I have to replace the flywheel in my Powerstroke, I definitely do not want to do that to my tractor every 10 years or so. But again, it comes down to the price of fuel vs. new starter.....

[Baby Grand]

jb - thanks for the lesson in remedial text entry. I'll try Notepad and see if that helps.

Regarding your observations:

"On idling, if it's so good, why do transport companies monitor idle time and reward the driver with the least amount? 'cuz it ain't so good to let them idle.

I'd bet you dollars to donuts that if you go to a truck stop tonight you won't hear the independents running their engines - they are paying for that burbling sound at $4.25 a gal! It didn't used to matter when fuel was $0.35 a gal, but now...."

I think you nailed it - the fuel cost is what the carriers are concerned about and why they reward operators who shut down quickly. I hadn't considered the exhaust gas temperature (EGT)/wet stack problem that several others mentioned, but that's probably a big factor, too.

For my own use, I generally shut down if I don't think I'll be moving anytime in the next 20-30 minutes. I'm with Ray66v and Jeff on not shutting down often. It all comes down to a cost/benefit trade and even at $10/gal I could justify a lot of hours idling vs the cost, ag and waste of my free time in replacing a starter or having to do bottom-end work.

jim