Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Steveplumb]

Like many others my coolant level sensor has not worked years, dash shows low level warning.
From research the only way to resolve this is to 'replace the tank'.
Taking the tank out and connecting to a meter I found the sensor did not 'switch' if I filled with water even though the float , floated perfectly.
However if I tipped the tank upside down so the float fell to the top then it switched every time. I also found if I lifted the float with a hooked wire it also worked
This intrigued me to the point that I had to find out what was happening here.
I stripped out the magnetic reed switch located under the tank. everything seemed ok there.
I then, with a sharp 6mm wood chisel carefully cut off the small ring of nylon that retains the washer at the top of the float stem. The 20mm approx washer could then be lifted off and then the float. It is too big to get out of the bottle but turning over the fault was revealed.  The magnet that is attached to the float is about the size of a thick M8 washer and is located in a recess on the underside of the float. The magnet had become detached from the float,  so when the the float raised the magnet stayed at the base of the stem, when turned upside down, the the magnet fell with the float, and with the wire hook; the hook went under the magnet and lifted it with the float. The magnet was a little bit corroded  but easily cleaned up .  I then glued the magnet back into the recess and replaced the float on the stem.  The nylon retaining washer is about 3mm thick so was just about able to countersink the hole so that the stem it sits on just protruded through the counter sunk hole. I then just heated the head of a 3" nail and carefully melted the bit of protruded stem into the countersunk area.
Sorted !   It took me hours to get to this stage but in fact now I know the issue its just  a half hour job.

[TheBoy]

Excellent

There are 3 common causes:

Magnet detaches, and if it's still reusable, your fix is perfect (though I've never been able to seal the top of the shaft very well, and the float pops off at some point in the future.  Never though to use a hot nail though, and I found using a soldering iron made a proper mess of the top, lol.

Float pops off - again your guide helps with that

The reed switch fails, or (surprisingly common) the joints on the small board are dry

[Doctor Gollum]

If the float pops off, it's because the plastic has degraded. Pieces of the washer can then enter the cooling system. Worst case the whole washer gets into a pipe and then you run the risk of cooking the engine.