I have a 97 Sable, the collant light just came on a few days ago, could not get it into the grage, holidays, the coolant seems to stay in if the car is not driven, and is ok, but dissapears when tar is driven, any ideas what this might be, I sm still wating to be able to get with my mechanic.
With luck it is a simple leak. It could also be a head gasket. Take a look at your engine oil and transmission fluid and hope that both look good.
Are you saying that the coolant level in the reservoir under the hood on the passenger side goes down when the car is driven? That’s normal. Does it come back up when you shut it off? If so, you may be lucky and only have an external leak. If it has a bad headgasket, you will probably notice A LOT of steam coming out the exhaust. SOME is normal, especially before the car warms up in cold weather. If the steam smells a bit like maple syrup, then you have a major problem.
You didn’t say which engine you have. Is it the standard pushrod engine, or the DOHC one? The DOHC is more prone to head gasket issues.
The coolant light will come on before any damage is done due to low coolant, but it still needs to be looked into. Just keep a sharp eye on the temp gage. Don’t let it get hotter than normal.
Have you noticed any coolant under the car after it’s been parked a while? Have you noticed any under the hood? It could just have a leaking hose or clamp. Just hope it’s not the radiator. The labor is horrendous. The plastic coolant reservoirs are notorious for cracking and leaking. They’re about $35 at Autozone, more from Ford/Mercury. Don’t try to change it until it has cooled down. You will not necessarily have to drain the whole (hole?) system, but can elevate the {approx} 3/4" hose on the bottom front of the reservoir to the point where little coolant from the radiator/engine will be lost. You’ll lose a little from the reservoir, but can catch most of it in a can placed under where you remove that hose. It’s fifteen minute job requiring a screwdriver and 10MM socket on a ratchet. I’ve done four or five of them this year.
The simple answer is that when the car is cold, the coolant contracts (all things get smaller when cold, expand when hot). Your cooling system has an overflow tank beside the radiator. As the coolant gets hot, it expands and the excess goes into a reservoir. You can find the reservoir by following the small hose thats just under your radiator cap to the plastic bottle (reservoir). When the system cools down after driving, the contracting coolant sucks the excess from the reservoir back into the radiator.
Apparently your reservoir has a level indicator in it, kind if like the gas tank. You need to keep a minimum level of coolant in the reservoir when cold, but not too much or it will overflow when warm. Your level has dropped, but as the car warms up, excess coolant goes into the reservoir and turns off the light. You need to add a little water to the reservoir, to the cold line on the side. Then you need to have your mechanic check for leaks and see if the system needs service. The coolant should be changed every 3-5 years.