[VAC] Re: [A/S] Engine Pre-luber

[Jim Dunmyer <jdunmyer@xxxxxxxxxxx>]

Gerald,
  Also, although many truckers let their engines idle for long periods, 
that's not really a good idea, especially with the small (relatively) 
engines in our tow vehicles. The cylinders cool down enough that you 
start getting incomplete combustion and the attendant cylinder washdown. 
You can also have trouble with the injectors; they're metering so little 
fuel at idle that they'll tend to coke up over time.

IIRC, the manual for my Dodge truck warns against idling for more than 5 
minutes or so.

Startup damage can be minimized by not revving the engine any more than 
necessary to start it and keep it running. There's enough residual oil 
in the bearings to prevent metal-to-metal contact until the oil pressure 
comes up. And, if you don't blip the throttle, the turbo won't be spun 
up before oil reaches the bearing.

It is also very important to allow the engine to cool before shutdown, 
especially in hot weather and/or after a hard pull. IE: don't swing into 
the rest area and immediately turn off the key unless you REALLY have to 
go. :-) Keep the engine at a fast idle for a few minutes, let it drop to 
slow idle for 5 or 10 seconds, THEN shut 'er off. Even using that 
preluber gadget to lubricate the turbo after shutdown isn't a substitute 
for a cooldown period. I've seen hot engines shut down and immediately 
boil the coolant; they don't do that if given a 5-minute cooldown. I've 
also observed low idle oil pressure on a hot engine that climbs during a 
cooldown period, indicating that the oil is cooling off nicely.

                            <<Jim>>