1992 J REG ASTRA

The temp sensor is at the back, on top of the inlet manifold.

The thermostat is probably in the end of the block, behind the cambelt. This makes it impossible to change without removing the cam belt first.

If the thermostat has failed then it allows coolant to flow everywhere (sounds like your case) A continually low temp reading would usually indicate a failed thermostat.

Radiators should be hot at the top and cooler at the bottom. The switch in the radiator operates the cooling fan on the radiator.

To prove the system, get it as hot as it usually gets then leave it idling, with the heater fan off, for twenty minutes or so, keep an eye on it, the temp gauge should rise and eventually the radiator cooling fan should come in and the temp gauge should fall a bit. This shows that the gauge works and that the thermostat doesn't.

mrcheerful

Ken The problem is that the temp gauge doesnt move from blue although the heater is working which indicates that the coolant is moving around only part of the system. The radiator is also cold at the bottom (where the temp sensor is?)

Is it something I could replace myself? Thanks Ken

I have the same thing going on in my astra, I had the new thermostat for a couple of weeks now, just tring to find a child free day so I can fit it.

Mike

That's the fan switch, not the temperature sensor, it should be cold :-)

And what a fecking nightmare it is to do what should be a dead easy job. Having spent the best part of a day on and off doing a similar one on a SO Cavalier once I wondered if a visit to the scrappy for inspiration was called for (getting some bits off another car to fit an easily accessible thermostat, wouldn't be sat in the block though) or whether I should have used the tried and tested repair method of sticking a bit of cardboard in front of the radiator. :o)