Low Coolant Pressure Alarm Project - LM393 - your feedback is appreciated

[Picaxxxu]

Hi guys!
This is my very first post here.
I've been following you for ages, now decided to register and share with you my design, to hear your thoughts and ideas about it, and maybe improve it.

History:
So, I've allready had a couple of cars that went to scrapyard because a radiator hose blew and engine overheated. No light or alarm sounded, and temp gauge was normal, since it measures water temperature, and there was no water...

Idea:
I need an effective way to be warned if a coolant leak happens. I though this could be done in a couple of ways:
- My first Idea was to dip two probes in the water reservoir, and measure it's resistance. When no water would be present, resistance should be 0, and an alarm would sound. Decided not to go this way, because there would be corrosion due to electrolysis, maintenance would be required.
- Second idea was based on my first, but using a stainless steel float switch in the coolant reservoir, but I'm afraid that it malfunctions overtime due to rust and grease present in the water.
- So I decided to measure the coolant circuit pressure. When pressure drops below some level, means there's a leak somewhere, and an alarm will be turned on.

Design:
So this is what I've got so far:

WPS1 will be a 5v 15PSI water pressure sensor, VOut ranges from 0.5v (0 psi) to 5v (15 psi).
LD1 - Red alarm LED
LD2 - Green OK LED
I'm using a LM393 dual comparator, with same reference and threshold but inverted between comparators, meaning that when comparator A is 'on', comparator B will be 'off', and vice versa. So when LM393's pin 3 voltage (coming from pressure sensor) is below reference the red LD1 will light up, and LD2 will go off. If voltage on pin 3 goes above reference, then LD1 will go off and green LD2 will be on.
Reference voltage is set using VR1, wich will be set to normal pressure when car is running idle.

I've breadboarded this, and it seems to be working fine.
I still don't have the pressure sensor, so I've just been testing with random input voltages, and it seems to be working as intended.

Still, since I'm a newbie enthusiast, I think there's always room for improvement.
Will it work as intended once assembled on car? Should I add any kind of protection or noise filter?

Any comments, thoughts or suggestions on this will be appreciated.

Thank you all!

 

[Bluejets]

When the systems leaks coolant , temperature and pressure increase so your whole idea cannot work. As far as probes are concerned, the resistance will not be zero without coolant but the opposite. There was a cure for the electrolysis action, gererate a type of ac signal to pass to the probes and use appropriate circuit to detect that. Built a couple that worked well but that was a long time ago. Should be something on a google search.

 

[Picaxxxu]

Hi Bluejets, thank you for your input.
How will pressure increase when there's a leak? If there's a blown hose, presure will be leaking, thus decreases.
My concern, since I have not received the sensor yet, is if a cold idle running engine has a measurable pressure, enough to be distiguished from a leak.

You're right, about the opposite resistance, rookie mistake.
I did make a while ago a bench working model of the probes approach, thats when I noticed electrolysis, and decided to search another path. I searched about it back then, and found about AC, but honestly I can't quite understand AC, and couldn't make or find a circuit that suited my needs.