running cool but blinking temp light

[albsure]

hi guys maybe i was cheering too soon. when i took her for a ride everything was good and then the red temp light started blinking. the temp never changed the fan was cycling on and off to maintain a consistant temp but the light is blinking. helllllllllllllllllllllllP? fellas if you have any ideas please don't be shy. i believe that i did all the air removal and purging properly. but just in case all thoughts are welcomed .

ps fyi heater core was bypassed in this car 3 years ago by the previous owner.

thank you, al b sure

[chrissev]

hi guys maybe i was cheering too soon. when i took her for a ride everything was good and then the red temp light started blinking. the temp never changed the fan was cycling on and off to maintain a consistant temp but the light is blinking. helllllllllllllllllllllllP? fellas if you have any ideas please don't be shy. i believe that i did all the air removal and purging properly. but just in case all thoughts are welcomed .

ps fyi heater core was bypassed in this car 3 years ago by the previous owner.

thank you, al b sure

If the gauge reads normal (half way up) and the light is blinking, you want to check the coolant sensor in the reservoir.  A blinking light with no change in the gauge position indicates low coolant level.  If the coolant level is not low, then the sensor in the reservoir could be bad, or the wiring to the sensor could be bad.

[albsure]

hello chris, thank you for the reply. do you know of a conclusive test for the sensor in the res ? i did all the stuff you and the  others suggested about getting the air out but maybe i should drain the entire system and start again. i have another res i'll swap it out tomorrow. if you think of anything else let me know. thank you. the day before when i finished the light was not blinking.

[chrissev]

hello chris, thank you for the reply. do you know of a conclusive test for the sensor in the res ? i did all the stuff you and the  others suggested about getting the air out but maybe i should drain the entire system and start again. i have another res i'll swap it out tomorrow. if you think of anything else let me know. thank you. the day before when i finished the light was not blinking.

Hi:  can't find anything on the subject in the bentley and I've never tested mine, but I am guessing that if you check the resistance across the sensor terminals, and then put the sensor in water and check resistance again, you should notice a difference (ie, there will not be continuity when the sensor is out of water, and will be some continuity when it is in water).  Also you could try cleaning the ends of the prongs on the end of the sensor that go into the coolant reservoir.

[Hammy]

I thought that, it's just a float inside the coolant reservior? Am I wrong in this assumption? If it is just a float, then the only reading that should be seen, would be an open contact (no continuity,when float level is low), and a closed contact (continuity, when float level is normal). I just removed my connector, put a jumper wire across the connector terminals, started the engine and let it run for awhile, no light. Pull the jumper wire out, and the dash light starts flashing.

 Am I wrong about thinking that this is nothing more than a float inside the reservior? Or is there a resistive sensor in there?

[chrissev]

I thought that, it's just a float inside the coolant reservior? Am I wrong in this assumption? If it is just a float, then the only reading that should be seen, would be an open contact (no continuity,when float level is low), and a closed contact (continuity, when float level is normal). I just removed my connector, put a jumper wire across the connector terminals, started the engine and let it run for awhile, no light. Pull the jumper wire out, and the dash light starts flashing.

 Am I wrong about thinking that this is nothing more than a float inside the reservior? Or is there a resistive sensor in there?

It's not a float.  It's actually two metal rods that stick down into the coolant.  They are covered in plastic and are uncovered at the very tips (where there is bare metal).  I believe that some current is able to flow through the coolant from one metal end to the other when both rod ends are submerged.  That is my theory as to how the sensor works anyway.  I found that I could fix my sensor by simply cleaning off the end of each metal rod (they were covered in coolant scum and slime).  I could be wrong.  But my guess is that is how it works.

For the OP's information, the sensor is very easy to remove.  It is screwed into the reservoir and can be removed with a pair of channel locks