Idling a Cummins engine

[woodylmiller]

We can bring the slides in with the engine running.  And, once the you go into gear the Valid system switches to "travel" mode and airs up the bags to "ride height".  So, about 5, 10 minutes at the most and we are under way.  I will get everything disconnected, do the "get ready" stuff on the toad, slides will usually be in, using shore power, by that point thanks to my DW/co-pilot, give a once around and then start the engine and bring the air tanks up to at least 100 psi, and after that as soon as we get buckled in, we're off to the races.

As to length of idle, I had always heard it was not a good idea due the engine not running hot enough to get a clean burn and unburnt fuel getting past the rings and into the oil.

Woody Miller

[Frank McElroy]

Woody - That's about the same as my procedure except that, I will do a final walkaround to verify that the coach is actually at ride height before leaving.

[willbo777]

I believe you should get the coach to ride height before bringing in the slides.  That is what Monaco always said.  

[Ivylog]

7 hours ago, Frank McElroy said:

Woody - That's about the same as my procedure except that, I will do a final walkaround to verify that the coach is actually at ride height before leaving.

And make sure everything is ready to go, including the roof antennas.

[cbr046]

1 hour ago, Ivylog said:

And make sure everything is ready to go, including the roof antennas.

I put little post-it notes over the transmission selector - antenna, jacks, power cord, tie-down (cargo), etc.  I can't move until all the post-its are back in their place (console cup holder) and no longer blocking the transmission display.  Air pressure is pretty obvious (to me). 

- bob

[Steve P]

On 10/21/2021 at 6:34 AM, willbo777 said:

I believe you should get the coach to ride height before bringing in the slides.  That is what Monaco always said.  

Maybe Monaco said that, even printed that, but the MH might not be level at ride height.  Common sense suggests to bring the slides in while the MH is level (on the hydraulic jacks).  Then retract the jacks.  Then I have no head bangers while disconnecting water and sewer.  Crank up the Cummins, raise the rpm to 1200 with 2 taps on the cruise.  While pressure builds, start genny, kill A/C's, disconnect shore power, start front A/C.  Drop Cummins to idle anytime during the process as soon as pressure reaches 115. Less than 3 minutes usually.  Finish up walk around and final check.  Park my carcass in the driver's seat and go.  It's loud, but brief.  5-7 minutes max.  I can put up with that from another MH owner, even at 6am, with a white noise app on my phone, or ear plugs.  And I don't have any hearing loss yet to further reduce the din.  If I couldn't bear it, there are islands for sale all over the world... Note to self:  make sure it isn't on the flight arrival/departure paths of any airport.  Example: Try camping at Sun N Fun, Lakeland FL airport now that Amazon is in and out multiple times every night to experience true noise pollution and annoyance.  Perspective is a valued companion. 

[willbo777]

The coach doesn't have the tendency to flex and possibly impede the slides at ride height.  Even if level especially with jacks the chassis could be twisted.  This subject has been coming up for years, Monaco built the coach at ride height, says in the manual to move the slides at ride height, and that's what I do.  It's your coach so obviously you can do it anyway you want.

[Steven P]

12 hours ago, Steve P said:

 Crank up the Cummins, raise the rpm to 1200 with 2 taps on the cruise.  While pressure builds, start genny, kill A/C's, disconnect shore power, start front A/C.  Drop Cummins to idle anytime during the process as soon as pressure reaches 115. Less than 3 minutes usually.  Finish up walk around and final check.  

Steve, if memory serves me right, I believe my Cummins manual says to not raise the RPMs  from idle until the engine temps have risen close to normal for operating. 

[Steve P]

1 hour ago, Steven P said:

Steve, if memory serves me right, I believe my Cummins manual says to not raise the RPMs  from idle until the engine temps have risen close to normal for operating. 

Well, time to get out the manual. Again.

[woodylmiller]

My ISM500 would take several miles, maybe more than that of driving to get to temp.  On idle I'm not sure it would ever get to normal.  As to slides; coach is built on a concrete floor which is perfectly level to begin with regardless of coach "height", therefore my reasoning would be to bring coach to level for both extension and retraction of the slides.  That's my story and I'm stickin' to it.  Also, my "ride height" has never been spot on level under any circumstances.  For the most part everyone is pretty much on the same page and it seems to be working.  No reason to sit and idle for 30 minutes prior to leaving.  

I have air only with my Valid system, no jacks.  From time to time while parked I have to relevel after the Valid "brain" goes to sleep.  But I wait till daylight hours, run the engine long enough for the low air alarm to stop and then hit the auto level button and shut down.

Since I'm beginning to see more and more "gas" class A's, maybe the diesel idle thing is going away, NOT!!  3 Tiffin gas coaches in this park right now, OK, whatever, saved some money.  Maybe it's just me, but lugging around 40,000 lbs with a gas engine after 50,000 miles, what's left in the tank?  Re-sale??  Friend bought a gas class A, tried to sell it, couldn't give it away, finally let the bank come and take it.  But that's a whole different topic.

Woody Miller

09 Dynasty

[96 EVO]

3 hours ago, Steven P said:

Steve, if memory serves me right, I believe my Cummins manual says to not raise the RPMs  from idle until the engine temps have risen close to normal for operating. 

Never heard of that!

Mine goes to 1000rpm hi-idle within 30 seconds of starting.

[RoadTripper2084]

4 hours ago, Steven P said:

Steve, if memory serves me right, I believe my Cummins manual says to not raise the RPMs  from idle until the engine temps have risen close to normal for operating. 

That doesn't sound right. AFAIK You are supposed to keep it a low idle until oil pressure is showing on the pressure gauge, then high idle. 

If it's cold out (<50f) I'll give it 30 secs anyway before high idle to hopefully give the oil a chance to warm up and circulate. Running the engine at a high idle is actually better for it than low as this will increase the temps and lubricity of the oil quicker.

[Pduggs]

52 minutes ago, woodylmiller said:

My ISM500 would take several miles, maybe more than that of driving to get to temp.  On idle I'm not sure it would ever get to normal.  As to slides; coach is built on a concrete floor which is perfectly level to begin with regardless of coach "height", therefore my reasoning would be to bring coach to level for both extension and retraction of the slides.  That's my story and I'm stickin' to it.  Also, my "ride height" has never been spot on level under any circumstances.  For the most part everyone is pretty much on the same page and it seems to be working.  No reason to sit and idle for 30 minutes prior to leaving.  

I have air only with my Valid system, no jacks.  From time to time while parked I have to relevel after the Valid "brain" goes to sleep.  But I wait till daylight hours, run the engine long enough for the low air alarm to stop and then hit the auto level button and shut down.

Since I'm beginning to see more and more "gas" class A's, maybe the diesel idle thing is going away, NOT!!  3 Tiffin gas coaches in this park right now, OK, whatever, saved some money.  Maybe it's just me, but lugging around 40,000 lbs with a gas engine after 50,000 miles, what's left in the tank?  Re-sale??  Friend bought a gas class A, tried to sell it, couldn't give it away, finally let the bank come and take it.  But that's a whole different topic.

Woody Miller

09 Dynasty

I do the same after parked for awhile. I have found my coach seems to stay level longer if I hit the auto level, wait for it to finish, then hit auto level a second time. 

[Chuck B 2004 Windsor]

Guess I am getting too old because it is hard for me to follow the air leak issue.  Once I got all the air leaks on my 2004 Windsor repaired, I did not have the many problems that come with air leaks.  Chuck B

[willbo777]

2 hours ago, woodylmiller said:

 

I have air only with my Valid system, no jacks.  From time to time while parked I have to relevel after the Valid "brain" goes to sleep.  But I wait till daylight hours, run the engine long enough for the low air alarm to stop and then hit the auto level button and shut down.

Woody Miller

09 Dynasty

I have a Valid system as well although I also have hydraulic jacks which I seldom use.  Your statement is confusing me.  When I level I hit Auto, and when the light goes from steady to blink  I shut off the coach.  It is still blinking after the engine is stopped and every 2 hours it wakes up and checks level, and if needed relevels.  After some time if it needs air to relevel the aux pump comes on.  I don't understand "goes to sleep"?  And doesn't your aux pump work?  I never start the coach to air up.  Just curious.

 

[Steven P]

From my manual:  I know high speed idle is not the same as no load, but this is what my manual says.  I'm pretty sure I remember someone who has done this way longer than I have saying he doesn't high idle until his Temps are up.  Another sentence says to use the high idle. 

Edited October 30, 2021 by Steven P

[David White]

9 minutes ago, Steven P said:

From my manual:  I know high speed idle is not the same as no load, but this is what my manual says.  I'm pretty sure I remember someone who has done this way longer than I have saying he doesn't high idle until his Temps are up.  Another sentence says to use the high idle. 

I assume this is the Monaco manual, not Cummins.  If my memory is correct, all the Cummins reps I’ve heard during presentations at Monacoers Gatherings, and others, state that only a short time idle is needed before increased idle to get air up. That is usually a question someone asks.  In fact, they don’t call for a 5 minute warmup before moving because you’re normally adequately warmed up by the time you leave a site to exit campground and getting on the road.

[saflyer]

6 hours ago, Steve P said:

Well, time to get out the manual. Again.

At a rally I attended the Cummins rep said it’s OK to drive before 150°F coolant temp, just don’t floorboard it. If on a lower speed limit road with light traffic I sometimes start driving but limit the RPM to about 1500 until 150° coolant temp. (For some reason I believe my HR manual says 160°.)

Ed         
‘05 HR Ambassador 

Edited October 30, 2021 by saflyer
More information

[RoadTripper2084]

57 minutes ago, Steven P said:

From my manual:  I know high speed idle is not the same as no load, but this is what my manual says.  I'm pretty sure I remember someone who has done this way longer than I have saying he doesn't high idle until his Temps are up.  Another sentence says to use the high idle. 

Yeah, so "no load" means not driving (by my interpretation, anyway). So fast idle is fine so long as you have oil pressure registering before you engage it.

I've also read in my manual that you can use the PAC brake to accelerate engine warmup by engaging it during idle. I've never tried that yet since I'm usually running around doing other things and not sitting there to push the floor switch for the PAC brake.

 

 

 

 

[Frank McElroy]

On 10/16/2021 at 9:25 AM, Chuck B 2004 Windsor said:

Cummins does not recommend running their engines while not driving for a long period of time because the engine plus the associated transmission does not reach operating temperatures.  Should I mention that while running your diesel in a campground can be irritating to your neighbors.  Why do you not go for a 25 one way drive?  Chuck B 2004 Windsor

That information is correct.  I looked up in the Cummins Operation and Maintenance manual for the ISC and ISL engines and for most with an ECM there is a fast idle option in the Insite software settings that after 5 minutes if in slow speed idle, under certain coolant temperature and air intake manifold temperatures, the engine will go into a fast idle mode to warm up the engine faster.  Monaco did activate that feature on my ISL.  On my engine Monaco did NOT activate the Engine Auto Idle Shutdown option so that if the engine idled at low speed for too long the engine would give a warning to alert that driver before turning off. 

Cummins considers idling a diesel engine too long before reaching normal operating temperatures engine abuse and that is one of the main reason for having the fast idle option.  Most engines with ECM will track the amount of engine low speed idle time.

In practice, once the engine starts and the oil pressure builds up to normal, you should activate the Fast idle option via the cruise control to shorten the time needed to warm up the engine.  The objective is that you want the engine once started to reach operating temperatures as quickly as reasonably possible.   Driving the engine slowly under minimal load as in driving through a campground to exit while the engine is reaching operating temperature is not a problem.  What you do not want to do is to accelerate under full load - foot to the floor - until the engine temp is at the normal operating temp.