Overheating, not pulling from overflow??
Hi, i'm going to ask if you've checked the fan clutch? with the engine running, do you feel a strong wind flow coming from the fan when you stand near it? If the fan clutch is not engaging, and it will still spin and look as though it is working, but it has no force. This will cause the engine to overheat. another thing to check is whether the electric fan comes on when you put the air con on.
1. If you don't feel a strong blow of air coming from the engine bay when it is running and the hood open, then very carefully and slowly try and see if the fan clutch is working by using a broom handle to hold it still when the engine is running. If it is working well, it will kick the broom handle out of the way. If not, the fan will just stop spinning with the broom handle holding it.
2. turn air con off and run engine. check fan clutch. If fan clutch ok, then turn air con on and see if the electric fan is running as well. If electric fan is not running as soon as you put the air con on, then the supply to the fan is faulty. This could be a fuse, a bad connection, or even switch relay.
The engine fan cannot cool the engine sufficiently on its own with the air con on.
an easy way to get air out of the engine coolant system is to take the cap off, and turn the engine on. with the engine cool enough, you can carefully squeeze the top coolant hose to push out the air and this should make the cooland level drop. top up the coolant through the radiator cap - not the reserve/expansion tank. with the rad topped up to the brim, put the cap back on.
do these tests first. They're easy and will let you identify if the system is working. If these are working, and it's still overheating, then it could be the rad cap becoming faulty, or even if its a replacement cap, it's rated wrong for the lbs, and doesn't let the radiator breath and let the expanded hot coolant flow into the expansion tank. This will make the engine overheat and build up enough pressure so that the coolant gets kicked out of the engine via a hose, splitting the radiator, or eventually the head gasket. This type of fault usually occurs when you sit still at lights, or parked up with the engine running, and you then notice collant squirting out. Also, especially after you've ran the engine and stopped the engine running. The build up of pressure has no where to go so the hot coolant from the engine pushes the coolant out of the nearest hole it can find.
Still, something is making it run hot, it could be the clutch fan or coolant pump.
Good luck.
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