GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: jack.pe on 15 July 2012, 16:58
-
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?
-
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
-
I have this exact same problem .. Try cleaning the connector on the expansion tank
-
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.
-
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?
-
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 :huh: also never mind where needle is at, as its position is affected by the temperature sensor, and totally ignore mfa readings
-
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 :huh: 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 :smiley:, just keen to understand the problem. Will do as you suggest !
Appreciate the help...
-
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?
-
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
-
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?
-
coolant fan comes on when the temp sensor in rad reaches a preset temp, it goes off when the same sensor senses coolant in rad has dropped below the preset.
neuspeed do a sensor that has a lower preset temp, or you could convert to a two speed fan set up. this has the fan come on at a slow speed at a lower temp and then switches to a high speed when very hot.
on mine i junked the oem fan and bought a pacet fan, i also bought a 13row mocal oil cooler kit. these two very rarely see oil temp rise above 100c even when driven hard on a hot day.
NB altho the needle on my temp guage showed it was 3/4 along guage the actual temp of the upper rad pipe was showing 85 with a laser temp gadget thingy used by the garage, so dont get focused too much on the needle. i usually go by a vdo oil guage in centre console, as for the mfa totally ignore that
-
thanks, so what sensor does the blink coolant light use?
-
My understanding of the red led (coolant too hot) circuit is that it is connected across the temperature gauge via an electronic circuit which gives it the flashing characteristic. As the sensor resistance lessens with the increase in water temperature, the voltage across the gauge increases which moves the pointer up. So to answer your question. The black coolant temperature sensor is the one that affects the red led. So then a fault with the electronic flashing gubbins may be a possibility. But you also have in the dash circuitry, a voltage stabiliser that could give voltage surges which could give a similar effect.
It might be better to get hold of another set of clocks, or maybe, the circuit from a set.
Dave
-
My understanding of the red led (coolant too hot) circuit is that it is connected across the temperature gauge via an electronic circuit which gives it the flashing characteristic. As the sensor resistance lessens with the increase in water temperature, the voltage across the gauge increases which moves the pointer up. So to answer your question. The black coolant temperature sensor is the one that affects the red led. So then a fault with the electronic flashing gubbins may be a possibility. But you also have in the dash circuitry, a voltage stabiliser that could give voltage surges which could give a similar effect.
It might be better to get hold of another set of clocks, or maybe, the circuit from a set.
Dave
Ok, so if this is correct and the thermostat that starts the fan is the same one sending the message to the dash light then surely the car is not overheating and the problem is in the dash? this is on the basis that the same switch does switch the fan on and off and that this seems to be working correctly?
I will still flush the rad but cant see how car is really overheating if the same thermostat that feeds the dash light seems to be working correctly and switching the fan on and off. Surely if over heating the fan would just kick in and stay on permanently, not switch off after a minute or two?
-
no the sensor that starts the fan is nothing to do with warning light, the warning light is wired to a sensor on the side of the head and sensor in expansion tank.
i feel you should seriously look at coolant flow remove and inspect/renew water pump, flush rad, when if ever was the water pump changed?
as your light only comes on when stationary in traffic and level is correct, then i would assume warning system is working ok.
when the clocks do go wrong the light flashes constantly from start up, i have had this with 2 sets of clocks
-
Check the smaller pipe to the expansion tank sometimes it gets clogged check the flow rate without cap off when cold if its small weeping there might be a blockage at that stage see if you can crush the small pipe along the length to see if it improves the flow
-
Will do...
Am also thinking of getting one of these so i can check the head temp, what do you guys think? should tell me if it is overheating or not..
http://www.ebay.co.uk/itm/Infrared-IR-Digital-LCD-...
-
Will do...
Am also thinking of getting one of these so i can check the head temp, what do you guys think? should tell me if it is overheating or not..
http://www.ebay.co.uk/itm/Infrared-IR-Digital-LCD-...
Guys,
Someone is lending me one of these laser temperature gauges, what is the normal temperature range of the engine? in Degrees Celsius please..
-
Success!!!!!!
Replaced all three temp sensors in the head and the light has stopped blinking!!
Also checked head temp with a laser gun and it is quite normal. Very pleased although in the meantime the starter motor has stopped working, trying to check if solenoid contacts are at fault.. it is clicking though so that is not the issue.
-
When my starter packed up last month it was the earth between the solenoid housing and the starter housing had corroded, get it off and clean it all up, remember to support the engine from below when you remove the bolts.
-
When my starter packed up last month it was the earth between the solenoid housing and the starter housing had corroded, get it off and clean it all up, remember to support the engine from below when you remove the bolts.
Thanks Jim, can the solenoid not be removed in situ, without taking the starter motor off?? there seem to be 3 splined allen heads holding the solenoid to the starter... but my splined sockets are too thick to reach while in situ.. is there any other tool I can use? allen keys would work but cant find the splined kind.
-
Try cleaning the terminals first. Disconnect the battery then take the power cables off and clean up the terminals with emery cloth.
Then smear some grease on them to stop corrosion