I'd personally drain the cooling system. Then re-fill. Once re-filled to max line, or just below it, run the car with the radiator / expansion bottle cap off. Run it for a minute, from cold, and give the accelerator a few blips. After a minute, switch car off and check level...top up if needed. Running it with cap off is to help get the air out of the system. The ideal coolant level is halfway between min and max, or 3/4. After topping it up again, wait for engine to go cold and repeat until level stops dropping.

I'd also check fan turns on (Usually when temp gauge reached 3/4). If not, check plug for switch has not become disconnected first or possible fuse blown. If your dad had to put stop leak stuff in however, then this suggests that it was leaking in the first place. I'd consider a new radiator if this is the case, if it's leaking from the radiator that is. It may even be leaking from a hose, it would be best to find out where the leak is if so.

since it occurred after adding bars leaks..( why?) its possible we have blocked an area up thus reducing cooling capacity or restricted flow. check out small hose return to header tank .this tube allows air as well as a small jet of coolant to get to header tank. its an essential part of system an dif blocked will cause over heating and not allow correct air lock bleeding causing same issues.

had this on my old rover V8 buick engine. remove the pipe if need be from hear tank and use a thin probe to ensure such pipes are free. have a check on coolant flow rate after starting ( cold engine) if we cannot see any flow to rad ( or header tank ) when revving then we have no or low coolant flow. ( possible blockage or pipe /rad ) try flushing system and back flushing.

Heat up the engine and feel the in and out pipes on the rad. If the exit pipe, th lower one, is cold at the point next to the rad then u have a blocked rad or faulty water pump. Rads only cost 20 quid and its an easy enough job so eliminate that first.

Your dad clogged up the cores in the radiator with that stop leak stuff .

Check to be sure your cooling fan turns on and consider a new radiator .

hello. no there was no leaking. i have no idea why he put it in. just an ocd thing i think. so a complete flush of the current coolant might do the trick?

last sunday night i drove my ford ka 2006 a 260 motorway journey. everything was fine. and the day after i drove around town all day with no problems. that night my stepdad topped up the coolant and also added in some bars leaks? the next day i drove the 15 min journey into town and the temperature light came on. by the time i managed to pull over steam was pouring out. i lifted the bonnet and the coolant had exploded out the top everywhere. my step dad said he had overfilled it by around half an inch. i set off again and the light came on and luckily i pulled in right in front of a garage. the mechanic said it was probably just the overfilling so i left it to cool and the light didn't come back again that night. however, the next day it came on again and every time i turned the fans on hot it went off. the coolant is leaking or going down? i took it to a garage and the man thinks its the head gasket even though there are no signs of such? he said he flushed the system and also took out the thermostat to see if it was that but that it wasnt? does anyone have any ideas? it doesnt sound like the head gasket to me if there are no signs?? many thanks!