2001 Cat 3126b, engine ideling- is it okay

[Mack Turner]

So for the diesel mechanics in the group, is idling the engine for extended periods of time good, bad or just normal wear and tear?

[Eric Maclean]

Mack
Generally extended idling is to be avoided for several reasons
1) because of low power/ temperature operation it promotes cylinder quenching ,wet stacking and cylinder glazing resulting in poor ring sealing and excessive blow by this was especially true of the older Detroit Diesel two strokes.

2) the engine and there for the engine oil don't acheived proper operating temperatures and doesn't boil off moisture leading to oil contamination and sludge build up requiring more frequent oil changes especially on a HUEI system like yours.

3) with newer engines were particulate trips are used for exhasts after treatment excess idling causes the particulate traps to fill with soot and if the engine isn't put through a stationary regeneration sequence the conditions will never be met for a proper regen and the system will eventually set codes ,derate and shut down possibly destroying the particulate traps.

4) and of course there's the whole fuel economy issue.

Bottom line excess idling is not good but if it can't be avoided the fast idle should be set to 1000/1200 rpm and the engine should be run to full operating temperature.

Hope this helps
Eric

[Mack Turner]

Thank you very much for the reply. On a lot of the Diesel Pusher groups on Facebook I'm seeing people say that it's actually good to let them idol and people claim they do it all the time especially during the winter, one guy referred to it as the engine taking a nap and lamented it was good for the engine on at least the older ones he claimed. Due to the heating systems being intertwined with the engine some people use the engine to heat their coaches if their aqua hot or such is not up to snuff. I've only had the coach for six weeks so just trying to determine best practices for starting her up in the morning and such, on a cold day should I start the engine and let it get up to temperature before I start driving and or how would one go about setting fast idle?

[Mike Shumack]

Eric is right.
Here's a video on the subject.

https://www.youtube.com/watch?v=hvfMal5fReA

[Steve Huber Co-Admin]

See http://beaveramb.org/forum/index.php/topic,8699.msg59796.html#msg59796 for a good discussion on idle times.
Steve

[Eric Maclean]

Mack
To set the fast idle the parking brake must be set the trans in neutral and the exhaust brake switch must be turned off,next turn the Cruise control switch to the on position and hold down the resume switch until the idle raises to the desired rpm to shut it back down simply touch the brake pedal or turn off the cruise switch.
Hope this helps
Eric

[Eric Maclean]

Mack
It's best practices when starting in the morning ( cold start ) to run the engine at fast idle for at least 3 to 5 minutes before operating the vehicle and then at medium load levels untill reaching full operating temperature.
This in reality is hard to achieve as an RV operator as there are many factors which make it hard to follow this guide.
I myself don't like to idle my unit in the camp ground because others don't really want to smell the diesel exhaust so on my coach I have a 120 volt air compressor plumbed into the air system to maintain my air tanks so I'm always ready to roll and with the Aquahot the engine is kept somewhere between 70 and 100 degrees which helps shorten warm up I suppose I could add a circulation pump in the engine heat circuit to move more heat back to the engine when not running but I have never found the need.
With the setup I have I start on a relatively warm day and drive off site after as little as 5 minutes
You will find you have little or no throttle response from your 3126 untill the ECM See's the engine is warm enough.
Hope this helps
Eric

[Dave Atherton]

Gentlemen good morning, this is a very common questions that come around several times. First
of all Caterpillar engines have with starting engine a program into the engine ECM is what is called
the cold mode. This cold mode with Heui injection systems allows engine to warm up and prevent damage to your engine. I receive many calls that I started my motorhome and it doing weird noises
and does not have any power than a 1/2hour later driving down the road that everything seems ok.
What is happening with the Heui injection system the engine injectors first go through a buzz test
that makes  sure each injectors getting oil, this is being preformed while the wait to start lamp is on.
While this function is happening the engine intake heater is also operating and is on a timer that
will operate even after engine is started until engine temperature reaches set point on the engine
ECM that engine is warmed up enough to drive. One of the biggest problems it seems we do not take
the time to correctly allow engine to warm up. Setting cruise control for fast idle etc. Depending how
cold outside temperature hard starting ( why ) because cold engine oil with the Heui injectors. Tip
that works on cold mornings starting cycle the key switch and wait to start lamp to go on/off several
3-4 times , this allows the injector buzz test on all injectors and allow the engine intake heater to
warm up longer since it is on timer. Last yes it is not recommended to allow extended idle with your
electronic engine even at a set fast idle as per your Caterpillar maintenance manual.
Dave Atherton Retired Cat Mechanic