[Spridgets] Ignorance is bliss

[David Riker]

Think it though.  It is really a "radiator bypass hose".  When the 
thermostat is closed, the water pump is still spinning, and still wants to 
pump.  Water comes out of the top of the head and usually goes to the 
radiator, cools down, then is pulled by the waterpump from the lower hose 
and pumped back into the engine.  So until the thermostat opens, the water 
pump just pulls the water down from the head, and circulates it back through 
the block in a smaller circle.  This allows the engine to warm up more 
quickly, and more uniformly without hot spots and cold spots.   Also, for 
those of us who still run a heater, that bypass hose means warm water begins 
flowing to the heater core almost immediately, instead of needing all the 
water in the radiator to be heated first, which in a cool or cold day could 
be...NEVER....  Yes, on a hot day, that is water that in theory is getting 
recirculated without ever seeing the radiator, but is is a very small amount 
compared to what passes through the much larger radiator hoses.  So, in a 
racing motor, block it off,  in Death Valley, block it off, for a street 
driven car in cooler weather, leave it be.
David R.


----- Original Message ----- 
From: "rrengineer @dslextreme.com" <rrengineer at dslextreme.com>
To: "Hal Faulkner" <frog.aye at gmail.com>
Cc: "Spridgets" <Spridgets at autox.team.net>
Sent: Monday, April 13, 2009 7:05 PM
Subject: Re: [Spridgets] Ignorance is bliss


> Vizard's book addresses the bypass hose on page 501 under "Thermostats".
> The bypass hose is actually called the "thermostat bypass hose".  It
> connects the water jacket adjacent to the thermostat to the water pump. 
> It
> was fitted to A series engines up to the early 80s.  Vizard calls the 
> bypass
> hose a nuisance and the hole in the pump and the hole in the head should 
> be
> plugged.  He says then drill two 1/4 inch holes in the thermostat to 
> prevent
> overheating in the event the thermostat gets stuck closed.
>
> On Mon, Apr 13, 2009 at 6:43 PM, Hal Faulkner <frog.aye at gmail.com> wrote:
>
>> I believe the bypass is there in order to cause the thermostat to open a
>> little sooner than it might otherwise.
>> Hal