On Sun, 19 Apr 2009 13:01:34 +0100, Mark wrote:

"Mrcheerful" wrote in message
om...
Trevor Smith wrote:
"Mark" wrote in message
net...
On the motorway last night and noticed my Sierra running very cool.
Temp gauge always gets about a third up the scale and stays constant,
but last night it was fluctuating between the edge of cold and only a
tad above.

If the thermostat change doesn't work it could be the temperature
gauge sender that's giving a false reading. As regarding the heater, a
mate of mine had a F reg pinto sierra and the heater on that was crap,
he tried everything to sort it including flushing the matrix with
fernox and it still wouldn't demist the screen in winter. He's now got
an escort and you could cook on the heater of that. Trevor Smith

flushing doesn't work when they are gummed up, the liquid physically
can never get to the end of all the blockages, it just goes round one
of the open routes and cleans that. the escort and sierra rad are very
similar size and shape so performance is close to identical, both are
very good heaters unless blocked up.

I'm not bothered about the heater I never get cold in a car and prefer
driving on the cold side and it works well enough to demist. Mainly
curious (and it is only curiosity) about the varying water level. As I
said, it drains and fills very quickly. Must be about two pints up and
down. Cycles over a minute, but the drain or fill is very fast (about 5
seconds)

Mark

I've seen this happen when there is an airlock in the system. Usually, if
you let it warm up to fan cut-in temp with the expansion tank cap off, it
will eventually push the air out.

Of course, with a non-working t'stat, it's going to take forever to get
that hot!

Chris

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