"Excessive Idling"

[tommybahama96]

From my Marathon Owner's Manual -

"Detroit Diesel engines should not be run for extended periods in "low" idle (approximately 1100 rpm). Fast idle should be used for extended idling periods"

OK . . . so when I use fast idle, ProDriver eventually flashes "Warning: Extensive Idling."

Aren't these two items contradictory?

Regards,

[truk4u]

Kind of bass ackwards... Low idle is about 600 and high idle is about 1,100. You can change the idle warning parameter on the pro driver, but I just ignore it.

[travelite]

That's right, my S60 experts advise to never idle the engine if possible. Always try to fast idle, around 1k rpm. At slow idle, 600 rpm, the combustion process cools and fuel and combustion byproducts slip past the rings and into the sump. To keep the heat up, you need 1000 rpms.

[tommybahama96]

Thanks truk4u and travelite. Makes sense.

BTW, I'm no "Senior Member" - POG assigned me that adjective when I joined. I'm just a guy trying to keep up with the most complicated object I ever owned.

[hhoppe]

Check out the lower oil pressure shown at low idle. Reason enough to heed the warning. Excessive wear on the camshaft and other engine parts can occur.
The excessive idle warning refers more to excessive fuel usage for no good reason.

[Jscott]

Thanks Tommybahama for asking that question, I had no idea not to let bus idle on low rpm...I too am learning as I go....and paying the stupid fee when i mess up!

[Reagan Sirmons]

According to the Detroit Diesel bulletin, it is my understanding that the slow idle is truly very inefficient and the excess unburned fuel enters into the oil as previously stated. This process through time results in sulphuric acid being created and attacking the bearings, etc., particularly while the engine is off for a long period. I shut my engine down after 4 to 5 minutes if it has cooled down and the turbo is at a normal speed. Sound about right?
Pres

[Mark3101]

3 to 5 mins should be a good guideline for shutdown after getting off the road. Usually, you are not pulling hard for a bit before stopping, so that should be plenty of time to get things cooled down. Mainly it is for the turbo...if you shut it off too soon, the oil can burn / cook in the bearing section which is bad. If I am stopping for a short time, I just flip it on fast idle and when stopping for longer, that is the timeframe I use.