Coolant Alarm

EA1191 · 18-11-2005, 09:47 AM

My latest attempt at a coolant level alarm may be OK.
Had the idea of using a magnet in a float and a reed switch to detect its position, but the few early tests failed. It would be easy to believe that Ford had anticipated someone would try to use that method and designed the tank to block it. I had decided that the only hope was to get a tank and cut it open to see if such a detector could be made to work. Then bought a stronger magnet and was very lucky to have perhaps the only combination of parts which will work.
The float must be small enough and the correct shape to be able to fit through the filling opening and to be able to support the magnet. A piece of tin plate was bent to a circle and three wire legs holds it just below the opening. The end of a paper clip is pushed through a very small hole drilled through the tin circle and through the bottom of the plastic wall of the opening towards the back of the car to hold the tin circle in the correct position. The cork float is located by a hinged wire frame which allows the float to move up and down with the changed coolant level, but in no other direction. The wire is pushed through the holes in the tin and bent around to make sure the wire cannot come out.
The magnet is a 2cm length of magnet from a magnetic cabinet latch which cost about $3 at Big W. The miniature reed switch cost a few dollars from Jaycar.
The position of the magnet and the reed switch is very critical because the tank has internal bits, the tank has limited clearance underneath for the switch and the magnetic field is affected by the steel below the plastic tank.
But with surprising luck it worked because there seems to be only one position for the magnet and the reed switch and the magnet floats about 1cm high and switches on if the level falls to below about 1/2cm.
As the car travels up and down hills, the level should change enough to indicate that it is working.
A better design should be possible. It would help a lot if a tank could be cut open and the internal structure revealed. The bottom of the tank could be 1cm or more thick.

spope · 18-11-2005, 01:40 PM

I have to ask the obvious question, what is wrong with the genuine ford part?
It is a magnetic reed switch, works perfectly well, even after they start to get covered in crud.

**Papa Smurf** · 18-11-2005, 08:33 PM

Yes, XF and EA Ghias had a low level coolant sensor in the Radiator. I am sure that will do a good job

18-11-2005, 10:37 PM

ummmmmmmm, all models above the GL have a coolant level sensor, and it displays a low coolant light on the dash ...

Even the models that didn't get the sensor, have a spot for it. you've just gotta cut it out ...

CruizinEB · 19-11-2005, 03:00 AM

thats right ^^^^^^^^^^^^, but if that what you want to do, good luck ;)

EA1191 · 19-11-2005, 09:45 AM

Questions about a sensor have been on the forum, but there has been no replies except to get one from a wreckers. There appears to be a place to fit one into the front of the filler tank, but did not want to risk water leakage onto the relays. No idea how they work or where they are fitted. A trip to a yard would involve most of a day plus fitting etc. It was not urgent, I have lots of spare time, took less that a day to make and fit, and cost less than $5.
Also it was a challenge and it was successful.

RED_EL_XR8 · 19-11-2005, 11:55 AM

I think you'll find the Ford level sensor has an internal supervised resistor configuration, it is a not a simple NO/NC switch.

The switch should be open at low level and closed when normal. Wire a 180 ohm resistor in series with the switch, and a 1K2 ohm resistor across the switch contacts and you have an emulation of the Ford setup. Then you'll need a transistor swich to turn your LED On & Off!

If it was me I'd rather put my efforts into working out why the tank level was dropping and devote my time/funds to resolving this.

EA1191 · 20-11-2005, 10:22 AM

All models above the GL have a sensor. What proportion of the total would that be?
The car is now 14 years old but there is no loss of coolant. But the chance is increasing.
Had an experience when most of the coolant was boiled off when the filler cap was not replaced. Lucky there was no damage and the extra heat softened the gaskets and stopped most of the small oil leaks. Could have been expensive and the gauge did not move out of the 'NORMAL' range. The computer stopped the engine.

RED_EL_XR8 · 20-11-2005, 10:27 AM

Quote:

Originally Posted by EA1191

All models above the GL have a sensor. What proportion of the total would that be?
The car is now 14 years old but there is no loss of coolant. But the chance is increasing.
Had an experience when most of the coolant was boiled off when the filler cap was not replaced. Lucky there was no damage and the extra heat softened the gaskets and stopped most of the small oil leaks. Could have been expensive and the gauge did not move out of the 'NORMAL' range. The computer stopped the engine.

OK I'll revise - If it was me I'd rather put my efforts into preventative maintenance to reduce the likelyhood of coolant loss and devote my time/funds to resolving this.

That said a coolant alarm is not a bad thing, it all about effort required and funds used.

ilsautomotive · 20-11-2005, 10:42 AM

Soudns like a neat little project. The one time my EA let me down it was a burst heater hose, and the trip computer/dash light was beeping its head off at me long before any damage was done. I wish more cars would have designs like that.

EA1191 · 27-11-2005, 11:13 AM

It does not work quite as expected. On the first downhill grade the warning light flashes, but when the engine is hot the volume of coolant seems to increase and the level rises. Would then need a very steep grade to show a low level. Strange because the metal and plastic would be expected to expand and leave more space. But have not had it very hot.
Also after adding some petrol treatment, the car seems to always start faster and the engine has not stopped unexpectedly. May be worthwhile for EA automatic sedans.