Community Forums

Craig N Deb · 04-09-2013, 08:28 AM

Hey all,
I have a question that some of you may have an answer to.....

As I travel with our Fleetwood Discovery 40X with the Cummins 350 Turbo Diesel, when stopping for a meal outside the coach do you guys shut of the motor or do you lock up and leave it running?
My friend who builds the turbos says it is better to leave them running but, he is into the big truck side of the business.
I have seen people that do both.....
What do you do and why????
Thanks
Craig

nightriderrv · 04-09-2013, 08:34 AM

I was a truck driver too and in the winter we left them running to keep it warm and not so hard to start by the fuel getting cold, in the summer let it idle for 3 mins then shut it down it's up to you.

Sky_Boss · 04-09-2013, 08:39 AM

Shut it down...

It is kinda like computers where they use to say leave them on but once you look at the mean time between failures you realize that the odds are strongly in your favor that normal start up and shut downs do not represent a tangible risk.

Now, if it was 20* or colder maybe I might keep it running but I'm so sure about that. Just remember to allow for a short period for the engine to cool down if it was running hot/hard before you do a shut down.

I just don't see any need to burn fuel to avoid a risk that is nearly non-existent. If I needed to keep something running in the coach, I would then choose to start the genny if it wasn't already running.

RustyJC · 04-09-2013, 08:48 AM

From the engine's point of view, if it were an older diesel, I might leave it running. The newer emission-controlled diesels are a totally different ballgame, however. They don't like extended idling as they load the DPFs and other exhaust clap-trap, requiring regeneration cycles - they're much happier running under load with higher exhaust gas temperatures (EGTs) that keep the emissions gizmos clean.

Rusty

dons2346 · 04-09-2013, 09:02 AM

Pull into a rest stop and count the number of trucks that leave their motor running. You won't find many.

docj · 04-09-2013, 09:06 AM

When coming off the highway it is important to let the turbo cool for a few minutes before shutting off the engine. Caterpillar's literature says that by the time you have driven to a place where you can turn it off it should be cool enough as long as that has taken ~3 minutes or more. The only times I really sit and let it cool is when we pull off the interstate at a rest area and sometimes we are in a parking space within a minute of slowing down.

RustyJC · 04-09-2013, 09:06 AM

Many Class 8s now have APUs (small diesel-powered auxiliary power units) to provide air conditioning, heat, etc. while the driver is on his mandated downtime. The pluses for APUs - they consume less fuel, have lower emissions and are easier on the main engine and its emissions equipment as compared to extended idling. The minuses for APUs - initial cost and their weight which eats into available PAYload (i.e., the freight that pays the bills!)

Many (most?) newer diesels have water-cooled bearing housings on the turbos that have largely eliminated the old coking problems experienced if you shut the uncooled turbos down too quickly. It's still a good idea to cool the turbo for a bit, though.

Rusty

lass · 04-09-2013, 09:07 AM

Quote:

Originally Posted by nightriderrv

let it idle for 3 mins then shut it down it's up to you.

Agree with nighttiderry, advise received during my PDI was set to high idle for 3 minutes and than turn it off. This allows the fluids to stabilize to normal temperatures.

Ed-Sommers · 04-09-2013, 09:08 AM

Idling a diesel for long periods, when not absolutely necessary, is normally done only by company drivers that do not have to purchase the fuel, or pay for the repairs, or are misinformed. IMHO

Ed

Frobogey · 04-09-2013, 09:18 AM

Having been a Feeder Manager for UPS (The largest Fleet of Tractor Trailers in the world) We instructed our drivers to turn them off at lunch or break. The Cummins engine is large enough that very little heat is lost in 1 hour even at 0 degrees. Another post suggested idling for 3 minutes before shut off. That is correct since it lets the turbos cool off. After parking your Diesel powered RVl or truck overnight and are leaving . Idle no more than 3 minutes. In fact when you are ready fire it up from cold, just idle out of the campground. That is sufficient. The guys that run them for several minutes are just wasting fuel and disregarding their camping neighbors. Those methods and driving within the ideal rpm range will get you several hundred thousand miles without major maintence. Have fun

becks · 04-09-2013, 09:38 AM

Quote:

Originally Posted by Frobogey

Having been a Feeder Manager for UPS (The largest Fleet of Tractor Trailers in the world) We instructed our drivers to turn them off at lunch or break. The Cummins engine is large enough that very little heat is lost in 1 hour even at 0 degrees. Another post suggested idling for 3 minutes before shut off. That is correct since it lets the turbos cool off. After parking your Diesel powered RVl or truck overnight and are leaving . Idle no more than 3 minutes. In fact when you are ready fire it up from cold, just idle out of the campground. That is sufficient. The guys that run them for several minutes are just wasting fuel and disregarding their camping neighbors. Those methods and driving within the ideal rpm range will get you several hundred thousand miles without major maintence. Have fun

+1 Great advice!!!!

Sky_Boss · 04-09-2013, 09:41 AM

Quote:

Originally Posted by Frobogey

... In fact when you are ready fire it up from cold, just idle out of the campground. That is sufficient....

My start procedure is:
1. Turn on key and start after the "wait" light goes out.
2. Upon start I check oil pressure and other gauges as needed.
3. Set idle to 1000 RPM.
4. Idle until air pressure purge valve pops.

At that point I idle roll as much as I can until water temp comes off peg. Beyond that I slow accelerate as needed until I see tranny fluid temps off the peg. After that...ROCK N ROLL!

Make sense?

fastcat · 04-09-2013, 09:51 AM

Our UPS daily pickup drivers shut the truck off every time they pull up and stop. They tell me it's a company mandated procedure to save fuel and maintenance.

I let my turbo cool down to under 350 F so as to not burn the oil in the bearings, then shut the motor off. Just a little over idle get the EGTs down real fast.

Skip426 · 04-09-2013, 10:04 AM

X3.. on Frobogey's post. many other posts on this subject, with the usual pros and cons, and mis-information. Cat manual says 3 min. shorter if you have slowed from highway speed by coasting. Cummins repair training school said the same. When an engine is not up to full operating temp, the piston rings are not sealing properly, allowing un-burnt fuel to wash combustion chamber carbon, down the cylinder walls into the oil. That's the main reason diesel engine oil gets black.
If your worried about the engine getting cold, temps below freezing, run the gen set and plug in the block heater.