From: floyd@eng.umd.edu (Mike Hughes)
Subject: Re: Warming up your car
Date: Tue, 14 Apr 92 19:15:53 GMT
Organization: University of Maryland

In article <1992Apr14.153329.6806@ucsu.Colorado.EDU> barr@tramp.Colorado.EDU (BARR DOUG) writes:

>In article <64590084@hpl-opus.hpl.hp.com> knotts@hpl-opus.hpl.hp.com (Tom Knotts) writes:

>>morning. His response was interesting. He said that he has rebuilt many
>>engines for many makes of cars. He has noticed in the past that there
>>was often excessive cylinder wear in engines whose owners claimed that
>>they let the car warm up before using it. His theory is that one should
>>drive the car immediately, because it will warm up to normal operating
>>temperatures more quickly, minimizing the wear that naturally occurs
>>when a car runs cold. Does anyone agree or disagree with this?
>>
>>Tom
>
>The ideal way to warm up a car is to put as few revolutions on the car as
>possible while still warming it up. The best way to do this would be to
>climb a hill in high gear at about 2000 rpm, under full throttle (essentially
>lugging the engine slightly). This would warm it up the quickest. BTW , the
>wear caused by warming up a car can be reduced by installing and using an
>engine heater. (It also gives quick heater response on cold mornings).

	GOOD GOD!!!???  What is the purpose of doing this?  Are you trying to
get the most heat out of the vents as soon as possible, while destroying your
engine?  I seriously hope no one follows this advice.  

	The best way to start/warm an engine is under PARTIAL load at varing
RPM's.  At first, the engine has minimal oil everywhere except in the pan.  
When the engine starts, the most wear is going to ocure on the softest, most
heavily loaded parts.  These parts are the crankshaft bearings.  To protect
them, it is advantagous to crank the motor over for a few revolutions before
the load of combustion is present.  An ignition-kill switch near the driver's
seat can acomplish this on a car that starts when the key is turned; and if
you have to press the gas pedal to make your car start...don't press it for
a while.  The purpose of this cranking is to allow an oil film to wedge it's
way under the crank before the crank is severly loaded.

	When the engine starts, it will quickly get oil pressure to all points
that receive pressurized lubrication.  The next concern is the other engine load
surfaces which get their lubrication from "splash oiling".  Such surfaces are
cylinder bores/piston skirts, camshaft lobes/lifter feet, rocker arms, valve
stem tips, valve guides (actually require VERY little lubrication...not a real
concern), and chains and gears.  These parts will usually receive more lubri-
cation as the engine RPM's increase, but RPM's should be kept down in a cold
engine because engine parts are designed to operate best at operating temp-
erature, and dammage may result if loads are servere and the parts haven't 
expanded to their normal dimensions.  More lubrication might reach different 
load surfaces at different RPM's, so the RPM's should be gently fluctuated.

	Now that everything has received ample lubrication, it is necessary to
shorten warm-up time.  This can be accomplished by the use of the affore-
mentioned block heater.  Applying a slight load further increases the produc-
tion of heat.  It should be mentioned that the above info is for a normally
asperated, 4-stroke, pushrod, overhead valve, gasoline, automotive engine.
There are exceptions, and I claim no responsibility for the application of the
above suggestions...-Mike

:Suicidal Tendencies=====> He's a carrier of death a stork in reverse,        :
: =8^) Mike Hughes  =8^( : he blesses you with sickness cause love is a curse.:
:Mail---floyd@eng.umd.edu: The arsenic in your Koolaid, the bomb in your mail,:
:Voice--(301) 340-0922   : he disappears in motion but leaves a bloody trail. :