coolant tank float

I removed the coolant expansion tank to replace a hose, and thought I would take the opportunity to give it a good clean (mostly just removing grime from the outside, as the inside is still very clean). 

It's the later model tank with the coolant sensor, and whilst rinsing it out, I noticed that although it moves freely, the float does not actually float in water, but having reinstalled it in the car, I does (just) float in the correct 50:50 mix of OAT coolant and water. By 'just' I mean that the float sits fully submerged, but with the top of the float level with the surface of the coolant.

It's not actually connected to anything in the car at present as the car lacks the sensor itself and the necessary wiring, so I don't know if this lack of boyancy is entrely normal, or whether it is likely to cause false triggers once I get around to adding the sensor and wiring. Does anyone know?




 

Mine floats about half way up far as I can remember.  I'll have a confirmation look when it's cooled down. 

2004 TF135 - Mine floats about half way up far as I can remember.  I'll have a confirmation look when it's cooled down. 

Thanks Vince, that would be much appreciated.

Right - I've had a look - and as with so much on this strange device its a maybe.
The float (or my float) does not seem to float entirely level.  As if one side is slightly heavier (the magnet?).
 

This is with the level slightly below MAX.  SO assuming the small ledge protruding out of the rear is also just below MAX.
 
Filling with this just covered would result in the float being at the same level as the coolant - just as your's is!  Hurrah! 

Thanks again Vince.

Mine seems to sit just below the surface of the coolant, even when the coolant level is low enough that the float has plenty of space to rise further on the guide peg if it was buoyant enough to do so.

Interestingly though, looking at your photos, it appears your float is made from a smooth plastic, whereas mine appears to be made from a semi-rigid foam or rubber type material - possibly semi-absorbant too as it seemed to change colour from vibrant coolant pink to a much paler pink as it dried out: I have no idea whether is is supposed to be semi-absorbant, or whether it has just become so with age and this is why it is less buoyant than I had expected, but I guess I will find out when I get around to wiring up the sensor! If I see false low coolant level warnings at that point then I will just have to replace the tank.

 
 

I tested mine by slowly pushing the float down with a coffee stick.   It had to go down to virtually empty before it activated and there is a 20 > 25 second delay. 
So if yours floats a bit low it will probably still work.  (Probably!)
I wasn't happy with the delay so invested in one of Bruce135's backup low water alarms that operated aurally and faster.  Usually give a cheery chirp on starting. 
( https://www.the-t-bar.com/community/5521-brucetf135/profile )

P.S. Cannot see how having a semi absorbent float would be an advantage!

Surely, the float being lower will mean the alarm will be activated earlier than if the float was above the level?

Daedalus wrote:

Surely, the float being lower will mean the alarm will be activated earlier than if the float was above the level?

Yes, but that's not what concerns me. My float is barely floats in antifreeze, and sinks in water, which may be by design, or it may be a sign that it has deteriorated over the years. Rocking the car, or the turbulence from coolant returning to the tank are enough to make it drop a little further below the surface, but without a sensor connected I cannot tell how low it drops whilst I'm driving.

I guess I will find out which once I get around to adding a sensor and wiring, but obviously frequent false alarms would render the setup almost as ineffective as no alarm at all.

Prsonally Id' not bother and just use one of Bruce's alarms like most of us here have done. Very easy to install with a dab of glue on the outside of the tank, connect a couple of wires and peace of mind thereafter.
There is much that is painfully complicated in this world so I do like to keep it simple and trouble free when that is so feasibly within reach.

Notanumber wrote:

Prsonally Id' not bother and just use one of Bruce's alarms like most of us here have done. Very easy to install with a dab of glue on the outside of the tank, connect a couple of wires and peace of mind thereafter.
There is much that is painfully complicated in this world so I do like to keep it simple and trouble free when that is so feasibly within reach.

Thanks. I've been in contact with Bruce now and am going to exactly that