my alfa runs at around 50degrees c and only reaches 90 if stood in traffic. I suspect the thermostat is stuck open how can i check this or could it be a faulty temp sensor. (where is the temp sensor I thought it was on the thermostat but i disconnected this and the guage still worked. After 15 mins running the temp is about 50 degrees , the top hose is red hot but the bottom hose is cool. Any suggestions anyone
1. You are correct when you say it's the sender unit that is knackered, but I'm not sure where it is. Possibly a single wire connected to the engine block somewhere. The water would be cooler after coming through the radiator, but maybe not that cool.
2. Maybe the water pump isn't working properly but I'm now guessing.
To check it,remove from engine and place
in a container of water.
Heat water whilst stirring to avoid hotspots.
using a thermostat,check the temp at which
the valve just opens.(The correct temp might
be stamped on the stat,i know some are).
see if it is within tolerance,usually
between +1 deg c and -6 deg c of the
correct opening temp.
Continue heating to check that the valve