Coolant light

[raferackstraw]

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 

[jack.pe]

thanks, so what sensor does the blink coolant light use?

[oakgreener]

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

[jack.pe]

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?

[raferackstraw]

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

[clipperjay]

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

[jack.pe]

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-...

[jack.pe]

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..

[jack.pe]

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.

[JimR]

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.