Should I idle up while parked for better oil pressure?

I read it somewhere in a Cummins manual I think....IDLE UP!

 

Detroit and Cummins both give a detailed explanation of this in their engine manaual- when the truck is idiling at low baseline RPM, they're not completing a full burn in the fuel in the cylinder. Some of this escapes into the crank case and tends to collect around bearing packs on the crank and the collected residue is usually high in sulfur and carbon which increase acidity leading to rapid wear and early failure of bearings on the crank and to a lesser degree, the cam bearings.


Can anyone confirm if the vacuum on post '07 EPA crank cases has anything to do with this?

 

Pretty sure I read it on an older truck than 07. I think the take away here is get a bunk heater.

 

On the DD's Detroit recommends 900 rpm.

 

My company wants all our CAT's idled to 1000 rpm and Paccar's from 950-1350 depending on outside temperature (no idling between -10°C and +15°C). The latter is to let the DEF system generate enough heat to do an "active regen" or whatever crap the thing does.

I've heard from several sources, both within my company and without, in real life and on the internet, that CAT's (and most older diesels) should be idled up from "dead idle" in order to properly lubricate the entire cylinder. Just think, you are rubbing metal on metal, with no lube, for hours on end and you don't think it wears?

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And in cold weather, you should be keeping an eye on the oil pressure and water/oil temps as well during idling. If you are parked facing a strong wind, and the engine temps drop, the ECM will apparently kick up the fuel consumption rate to keep the fluids warm.

I was in Regina a few weeks ago overnight, it was -33°C (-27°F) with a strong wind hitting the front of the truck, and even at 1200 rpm, I couldn't get my temps over 160°F... but apparently my truck has thermostat issues and that was a major cause of that particular issue. Engine fan kept kicking on every minute or so for about three seconds all night. My fuel economy has been crap lately. I've been told to idle to 1100 until they get around to fixing it.

 

Somewhat related do we still need to let engines cool down for a few minutes before shutdown? Remember reading that somewhere

 

More the turbo than the engine I think

 

If your EGTs are high when you park and you just shut the truck off, the heat can cause whatever oil is in the turbo to burn so we let them idle to cool the exhaust side of the turbo. That's my understanding of it anyway.

 

I always let my truck idle a little bit before shutdown. Volvo even says the same in there manual and dash.

 

Cat used to have a video out years ago regarding driving for fuel mileage. It covered things like progressive shifting, starting in a slightly higher gear when empty or bobtailing, what RPM to cruise at, etc. One of the things that was discussed is how long to let the truck idle before shutting down. Their answer was pretty common sense in that if you planned ahead for an off ramp and began slowing down well ahead of it, and drove real easy from there to where you were going to shut down, you could go ahead and shut it off. If you just got done pulling a steep grade with a heavy load you may want to let it high idle (1000 rpm or so) for at least 5 minutes, then low idle for a couple more, then shut it off.

I go by the pyrometer, and never shut my old mechanical engines off until the exhaust temperature is below 300 degrees. If I have been pulling hard I let it run at high idle with the fan on for quite a while just to let the various temperatures even out a bit, then low idle for 30 seconds or so before shutting it off. This has worked for me. I used to have a shutdown timer (mechanical gismo like setting a bathroom fan timer) that I really liked, but I can't find them anymore. I believe that in most all of the newer electronic trucks there should be a shut down timer available in the programming.