Low Coolant Light

[gsr20det]

Had an overheating problem last weekend (fan stopped working) and ended up having to replace the radiator, and put in a new set of hoses and a thermostat while I was in there. Strange thing is now I'm getting a low coolant light, although the car is topped off.

Is the sensor in the surge bottle, or somewhere else?

Also, is there a factory service manual for the SHO?

Thanks for the help!!

 

[SHO_Driver]

Yep it's in the bottle.

 

[SHOoff89]

The same thing happened to me last week. Just fill the bottle and you should be cool.

 

[sdpatt]

A couple additional notes on the level sensor in the expansion bottle. The LOW COOLANT light will not reset after coolant has been added to the expansion bottle until the ignition key is cycled off then on. If the level in the bottle is above the sensor tabs, they may just be covered with corrosion and need cleaning.

 

[SHOZ123]

It's probably dirty with the garbage that collects on the bottom of the overflow tank. just unplug it and never see it again. It's easy enough to check the level in the tank. Really don't see the need for coolant and oil level sensors in an enthusiast's car.

 

[Speedy_91_SHO]

Thats the problem, not all SHO owners are enthusiasts. My friend just got a 91 white plus. It is in pretty bad shape. It was a second car and garaged. You should see how dirty the engine bay is....
Oh...his name on here is SHOracer14

 

[sdpatt]

SHOZ123:
... just unplug it and never see it again.

That is not a good way to fix something. The only right way to solve a problem... is to solve it.

 

[ckinart]

SHOZ123:
It's probably dirty with the garbage that collects on the bottom of the overflow tank. just unplug it and never see it again. It's easy enough to check the level in the tank. Really don't see the need for coolant and oil level sensors in an enthusiast's car.

I know what you're getting at Paul, but it is possible for even an enthusiast to be happy that his/her Low Coolant light works. The rubber portion of one of the heater core lines on my '94 MTX burst last fall while I was driving, and the Low Coolant light was the first indication I received to tell me that something was wrong -- even before I could smell the antifreeze burning off of the rear exhaust manifold (which followed shortly thereafter).

It's not totally useless, and if a simple cleaning of the metal tabs and/or the overfill bottle can reset the Low Coolant sensor to a serviceable state, I'd say it's worth having.

Edit: looks like Scott beat me to it using far fewer words thumb

<small>[ September 24, 2003, 12:20 PM: Message edited by: ckinart ]</small>

 

[SHOZ123]

But Scott I disagree. I check under my hood every other day. The coolant and oil level sensors are worthless to me and with the disconnection of the coolant sensor I will never be bothered by it again. It is permanently fixed IMHO. Why spend the time and money on new sensors unless you want to keep the low value SHO in concourse shape and 100% stock condition? Just because the car came with a feature does not make it a needed or desirable item.

I don't see how the coolant sensor is going to help you whit the case of a broken hose. Maybe one that weeps and after a few driving cycles has drained the reservoir down.

The only way for the coolant to be drawn into the motor is through vacuum on cool down. I blew a hose and the reservoir tank was still full.

 

[rangerj]

Shoz123,

I too am an enthusiast. I check the fluid levels regularly as you do. But, I agree with Scott in that ignoring a problem, rather than fixing the problem, is NOT the way to go.

Besides, isn't this forum about how to keep everything working? I guess we can agree to disagree on this one! shrug

I prefer to keep everything OEM, or better, and in working order. If all you want is transportation that runs, the Escorts are cute!
rangerj

 

[ckinart]

SHOZ123:
I don't see how the coolant sensor is going to help you whit the case of a broken hose. Maybe one that weeps and after a few driving cycles has drained the reservoir down.

The only way for the coolant to be drawn into the motor is through vacuum on cool down. I blew a hose and the reservoir tank was still full.

Actually, that's incorrect. When a line bursts in the coolant circuit (which inherently requires that the system is hot and pressurized -- the radiator cap should then be open placing atmospheric pressure on the low side) with nothing but fluid between the breach and atmosphere (i.e. assuming you don't have a substantial amount of air in the system, which you shouldn't), the coolant exiting the system under pressure at the breach will create a vacuum with respect to the atmospheric side, which in turn will pull coolant from the overflow bottle. Perhaps when you had a hose burst, coolant was not drawn from the overfill bottle due to the "garbage" that had collected at the bottom, clogging the spout.

The warning system works, and should be properly maintained.

<small>[ September 24, 2003, 03:19 PM: Message edited by: ckinart ]</small>

 

[sdpatt]

But Scott I disagree. I check under my hood every other day. The coolant and oil level sensors are worthless to me ....

But it's those days you don't check that are going to get you. Also, you can't look under the hood while you are driving down the highway and it can be at that time that you hit a piece of road debris that ruptures the oil pan. How else would you be able to tell that your oil level is dangerously low if you didn't know the pan had been damaged?

I don't see how the coolant sensor is going to help you whit the case of a broken hose. Maybe one that weeps and after a few driving cycles has drained the reservoir down.

The only way for the coolant to be drawn into the motor is through vacuum on cool down. I blew a hose and the reservoir tank was still full.

Actually, he is right in that coolant from the expansion bottle can only be drawn into the system when the system pressure is below the pressure on the bottle's atmosperic pressure. When a breech occurs in the pressurized portion of the cooling system, the only things driving the fluid out of the system are the pressure differential and gravity. The system can't be at a vacuum (from the high velocity leak) or air would be drawn into the system rather than fluid leaking out. The pressure is what's forcing the coolant out through the hole.

The only way for the cooling systenm to be below atmospheric pressure is for the fluid to cool and contract after the engine has been shut down. During heatup and operation, the expanding fluid had been expelled into the expansion bottle (it is not an overflow bottle). See How Stuff Works for a good description of the cooling system operation. Watch how the system functions from cold startup to operating temperature in the animated image here.

If you want to fix the coolant level sensor then just fix it. If you don't care about it working then I don't care if you fix it or not. It's your car. I like to keep mine working. It's a reflection of ownership and personal values. What do non-functional systems say about yours?

<small>[ September 24, 2003, 05:08 PM: Message edited by: sdpatt ]</small>

 

[ckinart]

sdpatt:
The system can't be at a vacuum (from the high velocity leak) or air would be drawn into the system rather than fluid leaking out. The pressure is what's forcing the coolant out through the hole.

Perhaps I should have used the word syphen instead of vacuum. With a breach in the cooling system on the heater core side of the engine, flow restrictions in the coolant cavities of the engine block (between the radiator and the heater core lines) will create a pressure and volumetric gradient between the radiator and the breach. With the pressure still above 15 psi on the radiator side, the rad cap remains open (albeit for a limited time), and coolant can be drawn from the overflow bottle until the system evens out and the rad cap closes.

We could talk about it all day, but

sdpatt:
If you want to fix the coolant level sensor then just fix it.

that's all that really matters. thumb

 

[rangerj]

Now we are disseminating knowledge, and THATS what it's all about. E=MC squared! Man I love this forum!

Theasis, antitheasis, hypothisis, or something like that!!! Jump in here Bizzy, and give us a womans perspective.

All kidding aside folks, listen up because there is a whole lot of applied physics being taught here. rangerj

 

[SHOZ123]

All I know is I have driven over a million miles without the help of a low coolant idiot light. I don't need one now to tell me I forgot to check my see-through overflow bottle to see if the level was low.

 

[NotSoSlowSHO]

sdpatt:
It's a reflection of ownership and personal values. What do non-functional systems say about yours?

OUCH


But honestly... it isnt all that hard just to clean the coolant sensor to make sure it works shrug

 

[SHOZ123]

My profession is an industrial electrician. I see some of the most complicated automated machinery you can imagine. From my experience over the last 20 years with it is they usually take something that works perfectly well but develops mechanical wear and over engineer it until it becomes an electrical maintenance problem. This is a prime example of that.

What we usually do is re-engineer it so the problem goes away. If the problem is permanently removed then to me any way this is the better solution. Personally I would of rather have better functional gages rather than have the Ford engineers waste time on coolant level sensors.

It's odd that the sensor only works on a cooling system that does not have it's vacuum integrity broken. If your radiator is weeping at the seams the tank level will not drop appreciably. But the radiator will lose coolant.

I wish I had the desire to keep 100% of my systems working. But as I age and so do my cars I find better things to do with my time and money. FWIW my SHOs are some of the most reliable cars I've ever owned. Neither is 100% system functional though. But I still enjoy them, don't hesitate to drive them. And have remove systems the I deem unnecessary. Even when I buy a new car I am looking for ways to change things. I can always find a way to improve matters and in this case removing the sensor to me is an improvement. I should also remove the wire and save me a few ounces of weight.