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Coolant sensor install

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I want to rig up a loss of coolant sensor for my 2015 3.5NA Taurus Limited in case I have water pump failure or leak as the water pump is internal and grenades the motor from hydraulic forces before the temperature gauge can go up.

1 Is the reservoir/pressure tank even the correct place for said sensor. When I drained the radiator, the tank never drained. After refilling, the coolant seemed to siphon out of the tank at a certain height. 

I wonder if the damage would be done with water pump failure before the tank lost enough antifreeze to trip a sensor.

2 Is there a better place the sensor on one of the lines near the thermostat? Or maybe a Large Tee in the upper radiator hose?

3 I have found some Amazon stainless steel GEM style sensors for cheap enough (long shaft with floating SS donut around shaft). Seems I could drill a hole in top of the reservoir and still retain use of my Pressure Cap.

4 I have seen where others use a plastic piece with a floating lever/bar. That means drilling a hole in the side of the tank below the water level. Not as appealing.

5 I thought about installing a Gems sensor in the (easily replaceable) cap, but then I would lose the 18psi pressure relief and have to add something in a hose (possible).
6 Should I tie in series with the oil pressure sensor so low water would show up as low oil pressure !!! to get the point across to whoever is driving? 

I see only one wire to the oil pressure sensor, so I am guessing it makes connection (signal current only) when there is pressure and is open when low pressure (fail safe). So if I put the coolant sensor in line in series, it would cut the signal. I have no idea how amps, volts, and resistance come into play here as I have no specs on the oil pressure switch circuit.

7 Can I just use the right side headlight for a power source to the switch then an audible amazon buzzer since its only on when the engine is running (Auto lights is always on). False signal or maintenance alarm could be silenced by cutting the lights off. The sensors want no more than 0.5A so It might mean a relay if I can’t find a buzzer with that low of a draw. An engine on key on power source would obviously be preferred. 

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You are potentially creating a lot more problems than you are solving. Loss of cooling system pressure WILL result in overheating and coolant loss due to boil off. You MUST maintain pressure. Unless you can find a sensor that will not vent pressure, you just cannot use it. The degas bottle will not hold a threaded sensor unless you use a backup nut on the inside, then it is questionable because the they are just not that robust. They often fail on their own, without holes poked in them. 


The coolant is almost never lost all at once, and in that VERY rare instance, it would be too late anyway, as that kind of failure is a pump bearing failure, not seals. Pump bearing failure means the timing chain will jump and pistons will meet valves. However "all of a sudden" usually isn't, rather it is ignoring the signs as they come.


TYPICAL pump failure starts as a *gradual* loss of coolant in the bottle. Then "mystery" smell of antifreeze when warm. The pump weep hole will hold quite a bit before you see it, but it WILL smell. As it progresses, there will be streaking and leaks at the weep hole behind the alternator as the coolant loss is higher than the weep hole's capacity. There may be intermix of coolant (milky) in the oil at any point. Letting it go further will result in pump bearing failure. Again, the true problem is that most of these glaring signs are typically ignored until it is too late.


The majority of engine failures are due to coolant in the oil being ignored. Coolant does not lubricate. Get enough in the oil and your lube is gone. Lose lube, lose bearings. On a bright note, if there is intermix and the engine is running and NOT knocking, we have had pretty good luck installing a pump, dropping the pan and cleaning out, then changing the oil, getting it HOT, and changing the oil/filter. Repeat HOT oil changes until the milk is totally gone, typically 2 to 3 times. Not a guarantee, but we have several with high miles after repair still running around with no issues. 





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