How long do you 'warm up"? - Page 3 - PeachParts Mercedes-Benz Forum

spock505 · #31 09-30-2009, 11:42 AM

I have always used the rule;

'80% of engine wear occurs in the first 20 seconds of starting'

I would drive it gently until the engine reaches temp but would never rev past 1500 -1700 until hot.

Don't forget the transmission fluid will also be cold and may not have circulated properly.

probear · #32 09-30-2009, 05:31 PM

'Wet stacking' is real.
First thing you'll notice at truck stops is that usually, the engines are above a normal idle. I have an idle controller on my PSD and it is set to idle at 1200 RPM if left for any length of time. Normal idle is at 650ish.
A diesel generates very little heat at idle which is the primary reason to crank, give it 30 seconds and then go. Drive it easily until it gets to temp, but it will get there a lot quicker being driven.
I have a gravel road that is about 3/4 of a mile, so driving slow gives the engine several minutes to warm prior to even getting out on a secondary road.

lkchris · #33 09-30-2009, 06:55 PM

You understand, of course, that a diesel engine cools down when returned to idle.

Idling doesn't do much for "warming up," that is.

Gas engine runs at stoichiometric 15-1 air/fuel at all speeds.

Diesel speed varies by changing air/fuel ratio and at idle this ratio can be something like 150-1. Not burning much fuel means little heat. The engine is actually cooled by all the excess air.

Some modern diesels (Navistar as one example) include electronics to create a fast idle when it's determined idle is allowing excessive cooling.

Brandon_SLC · #34 09-30-2009, 08:17 PM

Depends on if I need to go up the hill, or down the hill. If I start up, back out and then go up my steep hill, the car moves at walk like speeds for the first hundred yards or so. Going downhill, no need to wait. But it takes the engine a long time to warm up going downhill in winter. I've thought about blocking off most of my radiator for really cold mornings, but have never gotten round to it.

Kelly · #35 09-30-2009, 09:16 PM

I was just wondering this morning if anyone had hooked up a fast idle on these. Can the ECU control fuel at all on the OM603 motor? Maybe confuse the temp sensor? Or would a fast idle have to be purely mechanical somewhere on the linkage? Would it be benificial at all?

I sure do love a nice toasty interior on cold mornings.

This Diesel stuff still has me scratching my head. 150/1 A/F sounds hot to me, since Oxegyn burns so much hotter than the catylist, however I suppose at some point all the excess air would start to cool it down. Wonder what that A/F is?

Anyway, its was interesting just how little the car actually warmed up this morning sitting at Idle for 10 mins. It got up to maybe half of operating temp.

KarTek · #36 09-30-2009, 09:48 PM

Quote:

Originally Posted by Kelly

This Diesel stuff still has me scratching my head. 150/1 A/F sounds hot to me, since Oxegyn burns so much hotter than the catylist, however I suppose at some point all the excess air would start to cool it down. Wonder what that A/F is?

In some respects, Deisels operate opposite of gas engines. Richer is hotter and leaner is cooler in a Diesel.

turbobenz · #37 09-30-2009, 09:55 PM

the manual says to start it and gently drive when cold