Haydn Coolant Alarm Still Driving Me Nuts....

[Mark Elvin]

OK,

The alarm sounds continuously whether it be engine on or just ignition on, the alarm does not stop

There is coolant in the tank, the battery is new.

I can get the alarm to stop by shorting screw in the header tank to earth, but a few seconds later it restarts.

The screw was cleaned only three months ago, surely it's not really realistic to expect the screw to be cleaned any more frequently than that as it means dismantling the LB installation to access the screw.

Anybody got any more suggestions?

[Tony x]

I know Haydn uses a particular type of stainless screw (marine grade I believe) and lesser stainless screws can cause the problem you describe. You could get a new screw, particularly if it is not the original... - personally, I'd go for titanium as that stuff is many times more corrosion resistant than anything else - all those surgeons can't be wrong.
Expect to pay £10, titanium is around 2000x the cost of steel to make.

This could be overkill.

[g8dhe]

When did you last put fresh anti-freeze in? Its that which lays down the coating for a while after its put in.

[Darkstar]

Has he earth wire come adrift?



http://enginewatchdog.com/tm2%20installation.html

Trouble shooting section at bottom of page

[haydn callow]

What voltage are you getting between the screw head and earth.....should be +/- 1.8 volts.

If you had new red coolant 3 months ago.....give the screw a good clean......that should cure the problem for good....or contact the webshop for a free replacement screw.

[haydn callow]

Has he earth wire come adrift?



http://enginewatchdog.com/tm2%20installation.html

Trouble shooting section at bottom of page

We are dealing with a coolant alarm here.......that link is to a temp alarm.

[Mark Elvin]

New screw fitted today, plus extra screw as suggested.

All fixed, despite me disbelieving.

Many thanks for your help

[Darkstar]

Has he earth wire come adrift?



http://enginewatchdog.com/tm2%20installation.html

Trouble shooting section at bottom of page

We are dealing with a coolant alarm here.......that link is to a temp alarm.

Something new learned.

[haydn callow]

Has he earth wire come adrift?



http://enginewatchdog.com/tm2%20installation.html

Trouble shooting section at bottom of page

We are dealing with a coolant alarm here.......that link is to a temp alarm.

Something new learned.

Actually nothing to do with a loose earth........putting a new sensor screw in is what corrected the fault.

The way these alarms work is that a small voltage/tiny amp currant is put into the cooling system via the sensor screw, this currant then goes to earth via the coolant to the engine block. The alarm is triggered when the coolant level drops below the sensor screw breaking the circuit.....the lack of coolant causes the resistance to rise, the alarm puts in more volts until the 2.8 volt trigger is reached.......simples!!!
However anything else that causes the resistance to rise will also trigger the alarm..ie..coating on the screw/ weak coolant.

There is no need to fit a second earth screw into the header tank. If doing this sorts out the problem it is masking a underlying problem.......

Try disconnecting thr second screw from earth......the alarm should work perfectly.

[Mark Elvin]

Mine was repaired by jsut the single screw, but I added the second anyway.

[haydn callow]

The second screw will not do any harm, it's just not required on the latest model alarm,