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Re: cooling?

To: "Jack W. Drews" <vinttr4@geneseo.net>,
Subject: Re: cooling?
From: TeriAnn Wakeman <twakeman@cruzers.com>
Date: Thu, 3 May 01 10:00:26 -0700
>Here's the question:  If I put a thermostat in it, should I make the
>bypass hose operable again?


If the bypass blocked off there is very little to no coolant flow through 
the engine until the thermostat opens.

Since heat cannot be quickly conducted away from the cylinders, hot spots 
develop. These can be hot enough to cause local boiling of the coolant 
into steam. The steam forces coolant back away from the hot spots letting 
them get even hotter.

The steam can force the coolant out of the head and reach into the 
thermostat housing where it quickly heats the thermostat. The super hot 
steam forces the thermostat to open immediately, allowing the steam to 
pass into the cold coolant of the upper hose where it rapidly condenses.

The now wide open thermostat allows cold coolant in the radiator to be 
rapidly pumped into the engine with consequent rapid cooling of the head 
and block. This commonly causes a cracked head and occasionally a cracked 
block.

Even if the coolant does not get hot enough to force steam into the 
thermostat housing there will be local hot spots within the head that 
causes uneven metal expansion followed by rapid cooling then the 
thermostat opens. This will also cause head cracks over time.

I would suggest a skirted thermostat and unblocked bipass or if you can 
not find one, a regular thermostat and a bipass block with a 3/8ths inch 
hole to restrict bipass flow but allow some to happen.



TeriAnn Wakeman               Marigold Ltd.
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webmaster@overlander.net      search engine optimization, graphics
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