Re: [alfa] no heat in alfa milano

[Ethan Schartman <ethans@xxxxxxxxx>]

> From: doug sedon <sedond@domain.elided>
> Subject: [alfa] no heat in alfa milano
>
> hi all,
>
> well, i only got two replies to my no-heat milano
> query earlier.  this is a car that has heat if i prime
> the heater core by squeezing the return hose to it.
> then, i have heat for as long as i want - as long as i
> do not drive the car.  it will idle - even at 2k rpms,
> if i keep something on the pedal - and heat will work
> fine.  as soon as i start to drive, tho, the heat goes
> away.
> the two replies both suggested faulty t-stat.  is it
> possible this could be the case, even tho my engine
> temp gage reads normally, when i'm driving?

it's a bit of a head-scratcher. IIRC, the coolant flows out of the
back of the heads to the heater core, then returns past the tee to the
reservoir and into the return hose from the radiator. squeezing the
heater return hose will momentarily raise the pressure across the
heater core. if your heater valve, or the control cable(s) to it ( i
can't recall if it is a push/pull cable or two pulls) are dodgy, then
the pressure pulse might be enough to force the heater valve open. if
the thermostat is functioning properly, and while driving it opens
more than it does at idle (not much extra heat is created revving the
engine with no load) then the drop in water jacket pressure could be
allowing the heater valve to close.

given what you've said, this is my best guess. i can't think of a
scenario in which you could have these symptoms and not have some sort
of problem in the heater circuit. just a dodgy t-stat would either
open late (and you'd be running with plenty of heat) or open early and
the engine would be running cool (and indicating it at the guage).

HTH,
-ethan schartman
-'87 milano gold
-princeton, NJ
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