Astra Underheating Mystery

Hi

My W-reg Astra (1.6l, 8v) only heats up (according to the temp gauge)
sometimes. And even when it has heated up, it often will cool down so much
the gauge doesn't register. In this condition it tends to stall easily and
is difficult to restart.

Aha, I hear you say - it's the thermostat stuck open. BUT, starting from
cold, with the car idling, the radiator top hose-stays cold, even though the
heater will deliver fairly hot air; so presumably the thermostat is in fact
closed initially.

Helpful ideas/suggestions welcomed.

Thanks

Steve

 

change the Thermostat, its the easiest way to eliminate it.
It doesn't take long.

 

Is it 'actually' not warming up, or is it just the gauge? It could be a
connection to the temp sender or the sender itself if this is the case.
When it says 'cold' is the top of the radiator cold or warm?

 

Thanks for the reply Paul. Unfortunately on my model, changing the
thermostat is a difficult job. Unbelievable though it sounds, due to
(mis)design, you have to remove the timing-belt, idler and other bits, and
disconnect one of the engine mounting brackets!!!!
If reassembled incorrectly, the timing is b***ered.

So I don't want to do this unless I'm absolutely certain it is the
thermostat!

Steve

 

I'm with GaZ - is it just a sender issue? Do the hoses and heater feels hot?

 

The heater always get hot and stays hot (well, pretty warm) after a few
minutes, even when when the gauge is on zero and the top hose is cold.

Over half an hou or so (typical journey) the temperature sometimes rises up
to about 80degC according to gauge but then goes down again. By the end of
the hourney the top hose is hot though.

Steve

 

For anyone still reading this, it turned out to be a poor connection on the
coolant sender. I'd decided to replace the sender to eliminate it as the
source of the problem and did a lot of fiddling trying to undo the
connection; I failed - it's a peculiar connector in an awkward place.

However, when I went for a drive shortly after, the heating system worked a
treat - went up to full temperature quickly and stayed there. And no
stalling (presumably incorrect signal was confusing Engine Management
Thingy).

Steve

 

Glad you got it sorted, especially without breaking the bank! And thanks for
come back here with the result as well.

Mike