Proper Idling

[alcoon61]

Can anybody tell me how I should idle this 2007 427 smog motor. Are you supposed to idle it up any when idling for extended periods or just let it rumble around at 600rpm. I know on my old detroit I they wanted you to rev em up a little. I am a rookie to this mack engine and not sure if it should be idled up or not? thanks and hope everybody on here has a Merry CHRISTmas.

[Lmackattack]

my opinion is that any time you let a engine idel more than 5 mins you should bump the idel up to aroud 800 RPM. It raises oil press and will burn a little cleaner.

[Terry T]

Back in the late '80's Cummins published a report stating that their engines should never be left to idle except before shut down. The maint director at Parrish Leasing (98% Mack fleet) copied the report and it went out to every driver in the fleet. From that point forward we were required to set the throttle, later with electronic engines the speed control, at 1,000 rpm or better. with the electronic engines if we did not set them up they would shut down after 3 minutes. Cummins reason for no idle was cylinder wall wash down by the fuel. Apparently the fuel pump delivered more fuel at idle than the engine could burn and the unspent fuel pushed passed the piston rings in effect washing grooves into the cylinder walls. I am not a mechanic and no longer have the report so I am going from memory. For this reason, Since that time I have never allowed an engine to idle if it has a throttle control or is electronic below 1,000 rpm.