Coolant light

[jack.pe]

Guys,

When car has warmed up and the temp gauge goes almost halfway the coolant level light starts flashing. I have checked and the level is fine, if anything slightly overfilled. If the car picks up speed the temp goes down and the light goes off but in traffic it warms up again and come back on. Can't hear the fan going on.. but most posts say it only does so once the temp gauge is at 3/4s and mine has never got that hot.

Could this flashing light also indicate overheating or is it just for the coolant level? When it comes on the dial is usually less than half way and on the digital readout it only shows between 90 and a  max of 100.. at what temp are these cars actually overheating?

[Thom89]

My guess... Impeller on water pump has corroded away, so flow is much slower than it should be, hence overheating while stationary,
While on the move, the extra airflow is enough to cool the system, so returns to normal
Similar problems can also arise from sediment blocking the radiator, try flushing the system out, to start with.

Thom

[Jimmyrallye]

I have this exact same problem .. Try cleaning the connector on the expansion tank

[raferackstraw]

take a 12v feed to fan to check thats working then while stationary and at idle allow engine to get hot to see if fan cuts in, if fan works with a direct 12v feed but does not come on when hot at idle change fan sensor in rad.
as thom said it could be pump but try the simple tests first.

[jack.pe]

ok thanks for the ideas, but when the light comes on the analogue temp dial is usually less than half way and on the digital readout it only shows between 90 and a  max of 100.. at what temp are these cars actually overheating?
Also I read elsewhere that the fan only comes in when the temp dial is at three quarters so if it is less than half way can it still be overheating?

[raferackstraw]

do the tests i said! ignore where the needle is at you need to see if the fan cuts in! if it does then as thom said it could be waterpump,
blimey mate we are trying to help dont ignore us  also never mind where needle is at, as its position is affected by the temperature sensor, and totally ignore mfa readings

[jack.pe]

do the tests i said! ignore where the needle is at you need to see if the fan cuts in! if it does then as thom said it could be waterpump,
blimey mate we are trying to help dont ignore us  also never mind where needle is at, as its position is affected by the temperature sensor, and totally ignore mfa readings

Thanks! Not ignoring you , just keen to understand the problem. Will do as you suggest !

Appreciate the help...

[jack.pe]

Ok, I let the car idle today and once warmed up eventually the red blinking light came on.

I believe the fan (and the thermostat switch) is ok as it came on shortly after the light started blinking. The first time that happened it actually made the light stop bliking and then the fan stopped, the second time the fan ran for a while and then stopped...but the light carried on blinking.
I also disconnected the expansion tank switch and shorted out the terminals on the plug (in case it was a faulty sensor there) but the light carried on blinking.

Does this mean it is definitely the impeller on the water pump?

I think this has only started happening after the last service, could it be that they topped up with too much antifreeze and now the system is not cooling as well?

[raferackstraw]

could be that the pump is on its way out and not flowing enough coolant, if you take off expansion cap and rev engine then you should see the coolant flowing into tank from the return pipe, this will indicate pump is working but maybe not at its best.
also i would remove rad pipes and flush rad with a hose, you may have a partially blocked rad also causing a lack of optimum cooling.
i would completely drain system and fit a new genuine thermostat and refill with a 50-50 mix and bleed system fully. follow rubjohnnys guide on bleeding system.
if and when you are sure that cooling system is working properly and the light still flashes, then your clocks maybe faulty. it would seem the warning system is working correctly as it only comes on when in traffic, so this may indicate a flow issue as stated by thom

[jack.pe]

could be that the pump is on its way out and not flowing enough coolant, if you take off expansion cap and rev engine then you should see the coolant flowing into tank from the return pipe, this will indicate pump is working but maybe not at its best.
also i would remove rad pipes and flush rad with a hose, you may have a partially blocked rad also causing a lack of optimum cooling.
i would completely drain system and fit a new genuine thermostat and refill with a 50-50 mix and bleed system fully. follow rubjohnnys guide on bleeding system.
if and when you are sure that cooling system is working properly and the light still flashes, then your clocks maybe faulty. it would seem the warning system is working correctly as it only comes on when in traffic, so this may indicate a flow issue as stated by thom

Thanks...will try your suggestions.
Do you know why the fan is not cutting in sooner? and why it sometimes switches off even though the coolant light is still blinking?