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Re: "Oil Pressure" & "old" overheating problem

To: "Peter C." <nosimport@mailbag.com>
Subject: Re: "Oil Pressure" & "old" overheating problem
Date: Fri, 28 Sep 2001 07:54:07 -0700
Cc: Geoff Branch <gjbranch@mediaone.net>, spridgets@autox.team.net
References: <21144-3BB44A7A-2896@storefull-226.iap.bryant.webtv.net> <5.0.2.1.2.20010928080637.02182740@mailbag.com>
Sounds good in theory, but when my engine overheats at sustained high speed
driving the temperature does not come down again after I get off the freeway and
drive at a sustained slower speed.  It just reamins at that high temperature 
until
I shut it off and let it cool down.
Mike MacLean Supercharged 60 Sprite

"Peter C." wrote:

> At 08:07 AM 9/28/2001, Geoff Branch wrote:
> >Ahhh, but won't more time in the radiator to dissepate heat mean more time in
> >the engine to pick up heat???   Where is Ron Soave when we need a lesson in
> >thermodynamics?
> ===
> Yes, exactly! And that is what you desire... heat transfer from the block
> to the air. The more heat transferred, the better (to a point, for fuel
> burn efficiency). We are not trying to lower the temperature reading on the
> gauge, we are trying to lower the engine temperature.
>          The mistake sometimes made is to interpret a gauge's low readings
> as being a sign of good, efficient cooling when in fact it could be that
> heat from the iron is not being transferred adequately to the coolant. I
> sometimes liken it to trying to cool a chunk of red-hot iron given only 5
> gallons of water to work with. Which would you rather employ, a spray or a
> dunk. This is the case for not removing a thermostat which is meant to
> inhibit the flow. Many heads have warped due to overheating in an engine
> without a 'stat.
>          The coolant needs to go slow enough through the engine to pick up
> the heat, but not too slow or the temperature difference between iron and
> coolant wont be great enough. It also need to go slow enough through the
> radiator to give off heat. By the same token, air needs to flow through the
> radiator slow enough to pick up heat, but not too slow so that the hot air
> lingers lessening the heat differential between coolant and air.
>          BTW, the coolant also needs to go past the gauge sensor slow
> enough to transfer the heat to the bulb. I don't think it can go too
> slowly, however, to adversely affect the true temperature reading.
>          HTH    Peter C
>          Mr Soave seems to have gone West, temporarily.



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