I've an old Astra 1.4 (low compression) which has always tended to overheat, either at 70mph or when stuck in traffic. The biggest problem seems to be that the fan cuts in far too late - when it gets above 100 deg. Is there any way to rectify this, such as by fitting a lower temp thermostat? Or are they all preset at the same temp?
At the moment all I can do is put the heater on full and open all windows, which in the hot weather is hell :(
replace the fan switch or add a manual switch.
mrcheerful
Have you checked the cheap and usual suspects - enough coolant, adequate flow of air through the radiator, flushed the coolant?
Otherwise, has the behaviour materially changed in the summer months? Most of my cars have had the fan cut in at just over 100 degrees, it's perfectly normal.
How do you know it's overheating? Is the coolant temperature entering the red section and a warning light coming on?
Yep - done all the obvious checks, and if I don't take emergency action it boils over. Much worse in summer than winter. Doesn't loose coolant except when it boils.
My Astra 1.4 had a stat that wasn't opening all the way. You could try that - they're cheap anyway!. If you're careful you can do it without disturbing the cambelt too much by just taking the bottom pulley off and moving it out of the way. I found out by watching an AA bloke do this to cut the middle out of the stat as a get me home thing a while ago. (The stat frame is part of the seal so you can't just remove the stat)
you need proper antifreeze and a good water cap, or it will boil even if everything is correct.
mrcheerful
Sounds like the pressure cap is faulty- a 1 bar cap (and leak free system) should prevent boiling upto about 120 deg C, and I doubt its getting this hot.
Tim..
Just had mine doing the same thing (1.4 R reg)...It was as per the prev reply...thermostat stuck half open...clue was in the cold weather the engine never fully warmed up properly....The temp sensor for the gauge is on the engine...the switch for the fan is on the radiator...as the water was only just getting through the thermostat to the radiator the engine sensor (gauge) was reading nearly into the red before the water that got through to the radiator triggered the switch...thermostat changed and now perfect....Themostat opens at 92...fan cuts in at 95
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