Vauxhall Astra Diesel Overheating

[belladrewmop]

My 1984 astra overheats when stationary in traffic and the internal heater fan does not blow out very hot air.

[Mortartube]

It sounds like you need a new thermostat. The thermostat remains closed when the engine is cold and stops the water circulating around the engine. This allows the engine to reach it's operating temperature more quickly. Once the engine (and cooling water), reach a certain temperature, the thermostat opens and allows the water to circulate to cool the engine to it's ideal temperature. The heater uses heat from the cooling system to heat the interior of the car. Replacement is a simple job and should take about 10 minutes.. A new thermostat should be less than ten pounds, even at rip off places like Halfrauds. Ask a friend if you're not sure and get them to do it or do it yourself.

[Jay70]

I would have thought if the thermostat was not opening the heater would have still blown hot as the heater matrix is normally fed by the water circulating around the engine block and not from the water circulating through the radiator side of the cooling system.  If the water level is low you may have a leek somewhere such as from the water pump or from the head gasket.  Check to see if there is any oil in the water (if there is any water left) and check for water in the oil by looking at the dipstick.  Also check the water pump is working and drive belts are ok.

[fishjason8]

my experience of this  problem  was  found to be an air lock in the heater matrix(radiator) which had gotten to a point  where it was pressurising the  water  system enough to hold the  heat in the block   I  qould suggest  flushing the entire  system  with a hose  Do this on a cold engine so as not to damage the  block or head

ope the water filler  car and  put a hose into the  bottle  is available      then remove the small hose from the   thermostat housing    slowly allow the water to go into  the   filler and flow  out  throught the thermostat housing  top  once this  runs clear     seek out the top hose of the  heater  rad located on the  bulkhead behind the  engine    undo this hose and  flush this through  with  the hose also once this runs clear   re connect the  heater  rad hose  and   fill the   filler  once more till the water  runs from the  housing  then while runing the  water re attatch the  top hose on  thermostat housing   this will assist in removing air locks  you  can now run the car     do this without the  filler  cap on  for   several mins  if you see air  bubles   in the filler  neck then the system is  bleeding  air out   once you believe there to be no air left in  system   replace the  cap and allow engine to warm checking that  heater is  turned on in the car    and producing heat at   good temps 

when resolved be sure to  replace anti freeze/coolant in the    system