Diesel engine idling

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earthman - 22 Mar 2005 04:40 GMT

As I traveled around this weekend I noticed a few guys at rest stops or
travel centers who would leave there pickups idle while they ran in to
take care of business. Now I know that big rigs will leave there trucks
on, but I understand that when they do, they crank up the RPMs a hair. By
not increasing the RPMS and leaving your truck idle, I heard it's not to
good on it. Does anyone know the "why?" Also, is there a length of time
that would be acceptable/harmful to a diesel to idle?

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Tom Lawrence - 22 Mar 2005 05:18 GMT

> not increasing the RPMS and leaving your truck idle, I heard it's not to
> good on it. Does anyone know the "why?" Also, is there a length of time
> that would be acceptable/harmful to a diesel to idle?

The concern with extended idling is that combustion chamber temperatures
drop off (because so little fuel is being used when a diesel's idling),
which will result in incomplete combustion, leaving some unburned fuel in
the cylinders. This fuel will wash down the cylinder walls, diluting or
removing the oil, and cause excessive wear to the rings and/or cylinder
walls, as well as contaminating the oil with diesel fuel (over time). This
is why on big rigs, they have an "idle up" feature, because guys will idle
them for hours on end (especially when it's a cold night).

For our engines, I'd say over 15-20 minutes would be considered "extended"
idling, and should be avoided. But for the time it takes to run in and pay
for fuel, lunch, restrooms, whatever - not a problem.

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Frank - 22 Mar 2005 19:25 GMT

> For our engines, I'd say over 15-20 minutes would be considered "extended"
> idling, and should be avoided. But for the time it takes to run in and pay
> for fuel, lunch, restrooms, whatever - not a problem.

And the starter is spared another cycle.

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Nosey - 22 Mar 2005 05:35 GMT

> As I traveled around this weekend I noticed a few guys at rest stops
> or travel centers who would leave there pickups idle while they ran
[quoted text clipped - 4 lines]
> Also, is there a length of time that would be acceptable/harmful to a
> diesel to idle?

It's a good idea to let a diesel idle for a few minutes to let the turbo
cool down before shutting the engine off.

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Big Al - 22 Mar 2005 15:08 GMT

>> As I traveled around this weekend I noticed a few guys at rest stops
>> or travel centers who would leave there pickups idle while they ran
[quoted text clipped - 7 lines]
> It's a good idea to let a diesel idle for a few minutes to let the turbo
> cool down before shutting the engine off.

On my 04 600 the owner's manual explains it. It also says if you do let it
idle for an extended period of time the idle will go up to 1,000 RPM to try
to keep the combustion chambers warm. Some years ago a Diesel mechanic told
me prolonged idle carboned up the injectors....

Al

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Greg Surratt - 23 Mar 2005 00:00 GMT

>>> As I traveled around this weekend I noticed a few guys at rest stops
>>> or travel centers who would leave there pickups idle while they ran
[quoted text clipped - 14 lines]
>
>Al

I wish somebody would modify the ECM program so you could hit the
cruise control switch and set the idle using the accel/decel controls
when the truck is not in gear. That would be a great feature if you
were running something on a PTO.

Greg

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Steve W. - 22 Mar 2005 20:09 GMT

Won't matter in a few years anyway. Many states are enacting laws to
make it illegal to idle ANY diesel for more than 5 minutes.
Already law in New York and Cal. I believe it is in PA as well.

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Steve Williams

> As I traveled around this weekend I noticed a few guys at rest stops or
> travel centers who would leave there pickups idle while they ran in to
[quoted text clipped - 3 lines]
> good on it. Does anyone know the "why?" Also, is there a length of time
> that would be acceptable/harmful to a diesel to idle?

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TBone - 22 Mar 2005 20:29 GMT

LOL, yet another law that is just about impossible to enforce.

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If at first you don't succeed, you're not cut out for skydiving

> Won't matter in a few years anyway. Many states are enacting laws to
> make it illegal to idle ANY diesel for more than 5 minutes.
[quoted text clipped - 16 lines]
> http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
> ----= East and West-Coast Server Farms - Total Privacy via Encryption =----

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earthman - 22 Mar 2005 23:22 GMT

So I guess the bottom line is, for a quick pit stop, letting it run is
actually a good idea. As long as you don't lock yourself out or somebody
steals it. If you plan on stretching or napping a little...shut 'er down.
Now all I have to do is keep an eye out for the deputy who'll keep us safe
by writing up an "illegal idling" citation. Dang...what next? I got
pulled over two weekends ago doing 58 in a 55 zone by a highway patrolman
who says he clocked me doing 70!!! The only way I dodged getting a ticket
is he tried to tell me my driver's license expired too...I had to tell him
this was still March and my license expires in April. ("Wellll...I'll let
you go this time.")

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Greg Surratt - 23 Mar 2005 00:01 GMT

>So I guess the bottom line is, for a quick pit stop, letting it run is
>actually a good idea. As long as you don't lock yourself out or somebody
>steals it.

I'm real paranoid about locking the truck while it's running. I can
use the key fob to lock and unlock the doors in most cases, but I
discovered (without the engine running, fortunately) that there are
some parking areas on the Navy base where I'm stationed that the key
fob doesn't work - particularly next to the schoolhouse where they
teach maintenance on the radar and satellite communications systems.
;-(

Greg

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FMB - 23 Mar 2005 01:39 GMT

>>So I guess the bottom line is, for a quick pit stop, letting it run is
>>actually a good idea. As long as you don't lock yourself out or somebody
[quoted text clipped - 9 lines]
>
> Greg

I take it you carry a chocklate bar in your shirt pocket and turn around
whenever it begins to melt?

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FMB
(only one B in FMB)

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Jerry - 23 Mar 2005 05:09 GMT

> but I
> discovered (without the engine running, fortunately) that there are
> some parking areas on the Navy base where I'm stationed that the key
> fob doesn't work - particularly next to the schoolhouse where they
> teach maintenance on the radar and satellite communications systems.

Use to run into that problem sometimes when parked on the pier.
Especially if a carrier was in port. I don't think they ever shut down
their radar. Anyway, discovered if I walked up to the truck and placed
the fob next to the door glass it would work ....... most of the time :)

Jerry

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Greg Surratt - 23 Mar 2005 10:52 GMT

>> but I
>> discovered (without the engine running, fortunately) that there are
[quoted text clipped - 8 lines]
>
>Jerry

Yeahbutt . . . it only takes that one call to the SO to bring another
set of keys from home and she'll NEVER let you forget it! ;-(

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