Where is the coolant tank n a 1997 deville?

There is no way to reset the light , you probably need a new coolant level sensor !
Coolant Level Sensor Description
The coolant level sensor monitors the coolant level in the cooling system and indicates if the coolant is low. This sensor is located at the base of the radiator surge tank and is not serviceable.
CHECK COOLANT LEVEL (2)
The IPC receives a discrete input from the engine coolant level switch. The engine coolant level switch is normally closed. When the engine coolant is low, the engine coolant level switch opens. When the IPC receives an open signal from the engine coolant level switch, the IPC displays the message on the DIC.
you have to replace this ,Radiator Surge Tank !

Well, if the coolant is leakimg from the HVAC drain, then you need a heater core, no matter what. You really have to jack it up and look, but I can give you a couple of pointers......

1. The water pump is leaking. That happens a lot. The coolant is leaking near the front of the car, near the center, but ever so slightly towards the drivers side. You need a special tool to replace it and I think gm has an updated cover and gasket.

2. The water pump housing is leaking. The gaskets that seal it to the block are made of plastic and deteriorate often. The coolant will be leaking at the center of the car, maybe up by the water pump, or back between the engine and transmission.

3. The heater hoses. I have only seen this 2 time, but the metal pipes corrode along the fire wall.

4. You could need a radiator. I have seen the side tanks leak a few times.....


Just A couple of places to look, but you have to get under and look....

There is an over-flow hose between the coolant recovery tank, and the top of the radiator just below the radiator cap, and there is also an over-flow hose from the top of the coolant recovery tank and it just hangs over the side of the recovery tank and runs the over-flow off out under the front of the passenger side fender well area.

These engines are know for leaking head gaskets. A good quick test for this is fill the coolant tank to the top with the cap off. Start the engine. If the the coolant blows out of the tank, you have a head gasket leak.

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.
If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.
The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.

I would use any Dex Cool approved coolant, but if you're on a budget, I would use any antifreeze that says that it can mix with any color antifreeze. The warranties are the same on both types generally 5 years or so.

The antifreeze sold at Walmart for car radiators is good (but don't use the pink antifreeze used for RVs for winterizing plumbing)

Use a 50/50 solution of water to antifreeze by volume when topping off yor radiator through the overflow tank.

The fuel pump is inside the gas tank.The electric fuel pump is a turbine pump located inside the modular fuel sender.
The tank must be emptied and dropped to access.

THanks for using FixYa - a 4 THUMBS rating is appreciated for answering your FREE question.

The most common overheating problem with the Northstar engine is a blocked purge line. It's job is to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank(not the cap!),this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank or trace the hose further back until you locate the blockage.

coolant sensor is located inside the extension tank.

Maybe this will help . although this is from a 1997 Caddy.


Cadillac DeVille Engine Coolant Temperature (ECT) Sensor Location