coolant light flashing

[Beckett]

right yesterday my coolant light started flashing when i was driving, so i pulled over to check the level, it was like 20mm over 'max' (checked it this morning when cold and was perfectly on 'max') but i am not sure what this is? i am guessing it is just the plug which goes in the top of my coolant tank, so hopefully off to the scrappy tomoro to see if i can find some spares to test them out! but twice it has been fine for a while! yest i parked up at a vw shop to collect a part and after that i am sure it was fine till i got home and used the car again! and today i filled up with petroel and after i turned car back on to go home about 5 miles it was fine!!?

so really confused to what it could be!
the polo manuel says it could be the fan fuse, so just checked that and the fuse is fine!
 polo g40 engine in a gt shell, done 8500 miles with the conversion and only time it has ever come on!??!?

if you need any more info and any help would be greatly appreciated! i hope someone on here has had the problem and can tell me ehat they done to resolve it lol

Many thanks ben xx

[cheys03]

Level in the expansion tank rising when hot sounds normal, hence the name. What's the coolant temperature when the light flashes? Have you seen/heard the radiator fan come on? From memory there's also a level sensor in the expansion tank, but I'm not sure if a malfunction with this or it's wiring would cause the coolant light to flash.

[Beckett]

Level in the expansion tank rising when hot sounds normal, hence the name. What's the coolant temperature when the light flashes? Have you seen/heard the radiator fan come on? From memory there's also a level sensor in the expansion tank, but I'm not sure if a malfunction with this or it's wiring would cause the coolant light to flash.

the temperature is varied, like for instance temp can get to normal driving temp about 70-8- in my car, and like earlia car was cold i drove ! mile to my gf's and it was fine, then parked up for a hour and got in and 10 seconds after car was on it started slashing and car was pretty much cold! cant say i have really heard fan come on never been listening out for it tbo. but can find out tomorrow, i am sure it does come on etc, but temp is never too high or anything like that.

recently replaced the thermostat and re bled coolant with new etc when i replaced it!! xx

[MartinB]

This happened with my GT, new expansion tank with built in sensor and job's a goodun.

[Beckett]

sweet cheers martin, read up and loads people have this issue!! hope to get one from scrappy off a golf maybe!!1 tis defo sort urs man? x

[scotsjohn]

This could also be an airlock in the cylinder head;i've had that a couple of times over  the years. Bleeding the system only takes a few minutes and might save a bit of agro.

[Beckett]

i have blead the system, took the header cap off, warmed up a bit, then undun the bleed nipple next to the heater, water was comin out but not very much, didnt seem to be any air. but car wasnt at full temp or anything, and also tried a mk3 GOLF header tankbut it still continuos to flashh, i filled the golf header up with water above  max and sealed it and lugged it into my car........

[scotsjohn]

Try bleeding with the engine up to temp and the cap for the header tank on so that the systems pressurised. Mind yer fingers don't get cooked.

[Beckett]

i think i may have solved the problem to this...... the coolant breather pipe at the top of the expansion tank wasnt pumping water through. it was stone cold, flushed out the coolant and blasted the system with a pressure washer it was working pumping hot coolant from the engine. and touch wood its never been back on. never knew that had water flowing through.....