The "Mazda Bongo" is the most common vehicle that our alarm is fitted to with over 3000 sales, the 100mm screw item is recommended for it.

The "Landrover Defender TD5" needs a 90mm Screw.


This alarm can be fitted to any vehicle that has a plastic header tank and is 12 Volt negative ground.

(24 Volt alarm is also available Click Here )

The circuit works by the coolant conducting electricity through it, and holding the alarm off.
The circuit is from one screw through the coolant to the other screw.
No coolant means no flow of electricity and the alarm switches on.

If your header tank is metal It can also be used with a float switch (see bottom of tet)

Sensor wires are 2.2 Metres long.

Ring terminals crimped on sensor wires and stainless steel self-tapping screws.

Ring terminal on ground wire.

The new circuit is smaller and is covered with a self-adhesive pad that insulates from being shorted to any metal parts,

and can be used to attach it to any convenient flat clean surface.


General Fitting Instructions.

This alarm has two white sensor wires and it is important
that the plain white wire is fitted on the top of the
header tank and the wire with the black stripe fitted on the side.
The red and black wires are the power wires, the black wire should be
screwed to any nearby grounded metal, and the red wire fitted
to any fused circuit switched on by the ignition key using the lowest
current fuse that is available.
If there is no spare fuse the red wire can be spliced into an
eisting circuit as it uses very little current even when the alarm sounds.

When fitting the long top screw into the header tank.
Care should be taken to avoid any baffle plates that may be in the tank.
If the screw tip or stem is touching a baffle plate it can cause the alarm to not function.
The long screw is fitted in the top of the tank as close to the tank centre as possible.
If the screw is not started completely vertical it may hit a baffle plate
by the time it reaches the full depth.
We have supplied two plastic spacers that should be fitted as shown in drawing 2.
They have be drilled to the correct size for the screws to create a thread when fitting.
Because they are forming threads you will need to hold the spacers with pliers or in a vice, make sure they are about 20mm along the screw before screwing into the tank so that they do not
contact the tank until well after the tank thread has been fully formed.
You will probably need to use an electric screw driver on the screws, this should be
done at the lowest speed possible.
If screws are driven quickly it will heat and even melt the plastic of the tank.
The spacers are used because the screw threads do not go completely to the
head of the screw and this would be where they are most needed as the screw is
tightened onto the tank. The spacers make sure that good threads are in the hole as
the screw goes tight. It also means that if you were to over tighten the screw it
would have to strip the spacer thread and the tank thread before failure.
Do not over tighten the screws, only one customer (out of about 3000) has ever reported a leak.
If there was any sign of a leak:-
just loosen the screw about 10mm and put silicone sealant around
threads and between the spacer and the tank then tighten again.
Do not put sealant on the ring terminal or the head of the screw.

I will be happy to answer any questions promptly via eBay messages


Drill bits needed:-

2.5mm for header tank screws

5mm for LED

7mm for test switch





This alarm will also work with most float switches and without any changes.

Most float switches have the option of N/C or N/O contacts, The sensor wires are connected to the N/C pair.
Some are N/C only and can be used.
Some are N/O only and cannot be used.
N/C means:- Normally closed contacts.
N/O means:- Normally open contacts.