Super annoying low coolant alarm going off until car warms up (earth issue??)

**Young Angus** · 2nd January 2018, 01:44 PM

So my silly low coolant alarm has a problem. It's super annoying. Started happening after the first round of mechanical work and then when I took it back they added an earth somewhere and it went away. Recently after a bunch more work from a different crowd installing driving lights and UHF the noise is back.

When I start the engine the low coolant alarm does its usual beep to tell me it's working, but then until some random point when the car warms up to operating temperature it seems (bit of a guess) the low coolant alarm keeps coming back on softly...Then loudly...Then it goes up and down in volume with the indicator or it gets lower if I put my foot on the brake or turn on the lights then it gets louder again...It's driving us bonkers and it doesn't go away until I've been driving for a while, the kind of while that leads me to think it's at operating temp.

All the mechanics are still on holidays so I'd rather sort this before then if anyone has any ideas what may be happening...Any ideas?

**trout1105** · 2nd January 2018, 02:04 PM

What type of low coolant alarm do you have fitted and where is the sensor/sensors fitted?

**edddo** · 2nd January 2018, 04:59 PM

this^

I have a low coolant alarm in the top of the radiator near the bleed hose.
It goes off if there is a bit of air in the system after I have played with the cooling system - so In my case it indicated air in the system/low coolant - as you would expect.
How is yours set up?

**Young Angus** · 2nd January 2018, 05:10 PM

I believe mine is also in the top of the radiator. This isn't just going off though, it's going completely bananas and then it shuts off. I will get a recording of it, that'll say a thousand words.

**Vern** · 2nd January 2018, 05:15 PM

Mines in the same spot, i ended up putting a longer sender bolt in. Fixed

**Fausto79** · 2nd January 2018, 09:41 PM

Mine does that the day after a long drive or if it has been sitting idle for a few days. Usually only keeps beeping until the engine is turned on. Once it was beeping on and off like you say and i unscrewed the bolt and dripped some coolant in. Then ran car and bled air out.

Mine is on top of thermostat housing though.

**AK83** · 3rd January 2018, 05:19 AM

I was thinking about this the other day ... could this somehow be related to your Redarc DBS solenoid getting hot too?

Then I remember you said that the low coolant alarm issue only started recently .. but what about the heating up solenoid?

I remember that your coolant alarm is on the radiator fill plug.
I suppose it's a silly question but is the radiator/reservoir actually full or at the correct level?

**biggin** · 3rd January 2018, 05:43 AM

Have you tried cleaning the sensor? A wire brush should do it.

**rick130** · 3rd January 2018, 07:26 AM

I wonder of the ejector line is blocked?

Otherwise as above, pop the sender out and check.
It may have scale buildup?

**trout1105** · 3rd January 2018, 10:34 AM

If your coolant alarm is constantly going off I suspect that you have a problem with the cooling system and Not the alarm itself.
You say that it self test on startup, this is Good.
The alarm doesn't activate until the engine warms up, This is telling me that the alarm is working properly.
What you are describing is consistent with there being air at the top of the coolant system when the engine heats up and this lack of coolant is setting the alarm off.
Does the level in your header tank fluctuate? Have you tried bleeding the air out of the coolant system? What New work have you had done on the engine?

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