Re: thermostate temperature and related question

[Hirsch <Catenary@domain.elided>]

Bruce & David wrote (it took two guys to ask this question <g>):
 =

> David T. and I were working on his 'new' '71 GTV and the temp.
> never got above 140 F (PO claimed it always ran at 140F).
> Discovered that the thermostat was leaking and replaced it
> with a new one. The temp now went up to around 145F. A
> thermometer in the radiator confirmed the reading on the
> instrument dial.  We opened the bleed screw on the thermostat
> housing and got some coolant to come out - no air.
 =

> The strange part is that the radiator got hot but the hose from
> the thermostat to the radiator never filled with coolant -
> meaning that the thermostat never opened.  Coolant was getting
> into the radiator by another route.  All the hoses seemed to
> be correctly routed.  And the hoses seem to be quite old
> - maybe original.

Are you using an official Alfa thermostat--one with a bottom
plate to close off the bypass hose? You can get cheaper
thermostats that will fit the housing, but these are single
stage units that don't allow the cooling system to work as
intended.

The two stage thermostat controls both the bypass hose and
the main exit hose which pours the hot coolant into the top
of the radiator. As the valve for the upper hose opens,
a lower extension plate closes the bypass. Use of a cheap
single plane thermostat does not close the bypass. With the
wrong thermostat much of the coolant just circulates in and
out of the engine block without passing thru the radiator.
For a better explanation of this and an illustration, see
the reference given below.
 =

> Is there supposed to be a coolant restrictor in one of the
> hoses? We couldn't find one by squeezing the hoses.

Assuming it's a Spica car there should be a restrictor in the
bypass hose. The bypass hose connects the thermostat housing
to the water pump. The absence of the restrictor shouldn't
affect the ultimate coolant temp much, but will help the car
warm up faster. Take a look at the article "The Bypass Coolant
Restrictor--What's it for?" on the i Saluti website at: =


   http://www.geocities.com/MotorCity/Downs/3837/bypassco.html

For some reason only the Spica-equipped cars used a restrictor
in the bypass hose. Cars with carbs didn't use them.
 =

Good luck,
 =

Rich Hirsch
'87 Milano
'78 Spider
'67 Duetto
'66 Sprint GTV
Editor, i Saluti, St Louis AROC
Website: http://www.catenary.com/victor/isaluti

------------------------------