Where does this go?

A worn water pump is the most likely. If the coolant is going down, the water is going somewhere.

The most common reasons an Oldsmobile Alero is overheating are a coolant leak (water pump, radiator, hose etc.), the radiator fan, or a failed thermostat. Coolant leak (water pump, radiator, hose etc.)

Oldsmobile Alero Overheating - RepairPal

Videos on overheating. You probably have air in the system from when you replaced the thermostat. The coolant system needs 'burping' of air.

https://www.google.com/search?q=2000+Oldsmobile+Alero+running+ho

Burping

https://www.google.com/search?q=burping+coolant+system

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It would have been useful to know where the hose from the tee goes and what diameter as that is new to me. 50 years as a repairer and I have never seen a top radiator hose with a tee branch.

Usually the engine heats and the thermostat opens and starts coolant circulating through the radiator, up the bottom hose into the water pump to be pushed round again.
The volume of coolant moved by the water pump, even at idle should be far in excess of that circulating through the heater matrix ensuring adequate circulation through the radiator as soon as the thermostat opens.

The top hose must be hot because the thermostat is open so why doesn't the coolant go further and heat either the branch or the rest of the hose and radiator...
Sometimes a pump with a plastic impeller will lose a vane and overheating due to insufficient circulation is likely.

Other things are more common - semi-blocked radiator tubes restricting coolant flow.
Silt build up in the cylinder block causing hot spots in the cylinder walls.
Restricted air flow through the radiator.
Electric coolant fan not working.
Excess combustion gas in the cooling system interfering with thermostat operation.
Degassing system blocked with the same result.

The water pump is enclosed on the front of the engine. The bottom radiator hose connects to the water pump inlet.
You do not add coolant to the water pump. You add a 50-50 mix of antifreeze and water into the radiator cap opening. Or you can buy the coolant already mixed with water and just pour it into the radiator.

The coolant system uses the water pump to circulate the coolant through the engine and then into the radiator via the upper radiator hose for cooling it off, and it then goes back into the engine through the bottom radiator hose. When the engine is warmed up, the coolant constantly circulates through the engine to radiator and back into the engine.

Removal & Installation

• 4.6L & 5.4L SOHC ENGINES
• 5.4L & 6.8L ENGINES
• 5.4L DOHC ENGINE
• 6.0L DIESEL ENGINE

Print

4.6L & 5.4L SOHC Engines

1. Partially drain the engine cooling system to a level below the thermostat.
2. Disconnect the upper radiator hose from the water outlet adapter.
3. Remove the power steering reservoir upper mounting bracket.
4. Remove the bolts and remove the water outlet adapter.
5. Remove the water thermostat and the O-ring seal. Discard the O-ring seal.
6. Installation is the reverse of the removal procedure. Tighten the water outlet adapter bolts to 18 ft. lbs. (25 Nm). Tighten the power steering reservoir upper mounting bracket as shown in the accompanying illustration.
   
   

   Fig. View of the power steering reservoir upper mounting bracket and tightening specifications
   
   
   

   Fig. Exploded view of the water outlet adapter and tightening specifications
   

5.4L & 6.8L Engines

1. Partially drain the cooling system to a level below the thermostat.
2. Disconnect the upper radiator hose.
3. Remove the coolant outlet connection, as follows:
   1. Remove the bolts.
   2. Remove the coolant outlet connection.
   
   
4. Remove the (A) coolant thermostat and the (B) O-ring seal.
5. Discard the (B) O-ring seal.
   
   

   Fig. Remove the (A) coolant thermostat and the (B) O-ring seal
   

To install:

NOTE Thermostat must be installed as illustrated.

1. Use a new (A) O-ring seal to position the (B) coolant thermostat in the (C) upper intake manifold.
   
   

   Fig. Use a new (A) O-ring seal to position the (B) coolant thermostat in the (C) upper intake manifold
   

2. Install the coolant outlet connection, as follows:
   1. Position the coolant outlet connection on the upper intake manifold.
   2. Install the bolts and tighten to 15-22 ft. lbs. (20-30 Nm).
   
   
3. Connect the upper radiator hose.
4. Fill the cooling system.

1. Before servicing the vehicle, refer to the precautions section.
2. Partially drain the cooling system to a level below the thermostat.
3. Disconnect the upper radiator hose.
4. Remove the coolant outlet connection, as follows:
   1. Remove the bolts.
   2. Remove the coolant outlet connection.
   
   
5. Remove the (A) coolant thermostat and the (B) O-ring seal.
6. Discard the (B) O-ring seal.
   
   

   Fig. Remove the (A) coolant thermostat and the (B) O-ring seal
   

To install:

NOTE Thermostat must be installed as illustrated.

1. Use a new (A) O-ring seal to position the (B) coolant thermostat in the (C) upper intake manifold.
   
   

   Fig. Use a new (A) O-ring seal to position the (B) coolant thermostat in the (C) upper intake manifold
   

2. Install the coolant outlet connection, as follows:
   1. Position the coolant outlet connection on the upper intake manifold.
   2. Install the bolts and tighten to 15-22 ft. lbs. (20-30 Nm).
   
   
3. Connect the upper radiator hose.
4. Fill the cooling system.

5.4L DOHC Engine

1. Partially drain the engine cooling system to a level below the thermostat.
2. Disconnect the upper radiator hose, the heater water inlet hose and the heated PCV inlet hose from the water outlet adapter.
   
   

   Fig. Disconnect the upper radiator hose, the heater water inlet hose and the heated PCV inlet hose from the water outlet adapter
   

3. Remove the water hose connection and thermostat.
4. Installation is the reverse of the removal procedure. Tighten the mounting bolt to 18 ft. lbs. (25 Nm).
   
   

   Fig. Exploded view of the thermostat-5.4L DOHC engine
   

LOOKING AT HEATER CORE TOP HOSE COOLANT FLOW IN BACK OUT THROUGH THE BOTTOM HEATER CORE HOSE CHECK WATER PUMP BYPASS HOSE SEE IF IT GETS HOT.IF NOT COULD BE BLOCKAGE AT BYPASS HOSE FROM WATER PUMP OR WATER COULD BE FAULTY GETTING TOO WEAK PUMP COOLANT THROUGH SYSTEM.IF COOLANT GETTING HOT GOING TO HEATER CORE THE HEATER CORE AND COOLANT SYSTEM NEED FLUSHING OUT.

1988–91 Models

1. Disconnect the negative battery cable.
2. Properly drain the cooling system into a suitable container.
3. Disconnect the fan motor and motor connector.
4. Disconnect the upper and lower radiator hoses.
5. Disconnect and plug the automatic transaxle cooling lines at the radiator, if equipped.
6. Disconnect the coolant reservoir overflow hose.
7. Remove the radiator attaching bolts and brackets.
8. Remove the radiator with the cooling fan attached.
9. Remove the cooling fan and shroud from the radiator. NOTE: Check all cooling system hoses for any signs of damage, leaks or deterioration and replace if necessary. To install:
   
10. Attach the cooling fan and shroud to the radiator and install the assembly.
11. Attach the radiator bolts and brackets. Tighten the radiator bracket bolts to 7 ft. lbs. (10 Nm).
12. Connect the coolant reservoir overflow hose.
13. Connect the automatic transaxle cooling lines to the radiator, if equipped.
14. Connect the upper and lower radiator hoses.
15. Connect the fan motor and thermo-switch wire connector.
16. Refill the system with the proper type and quantity of coolant, check for leaks and bleed the cooling system.
17. Reconnect the negative battery cable. Fig. 7: Cooling system components — 1988–91 engines
    

1992–95 Models

1. Disconnect the negative battery cable.
2. Properly drain the cooling system into a suitable container.
3. Disconnect the fan motor and motor connector.
4. Disconnect the upper and lower radiator hoses.
5. Disconnect and plug the automatic transaxle cooling lines at the radiator, if equipped.
6. Disconnect the coolant reservoir overflow hose.
7. Remove the radiator attaching bolts and brackets.
8. Remove the radiator with the cooling fan attached.
9. Remove the cooling fan and shroud from the radiator. NOTE: Check all cooling system hoses for any signs of damage, leaks or deterioration and replace if necessary. To install:
   
10. Attach the cooling fan and shroud to the radiator and install the assembly.
11. Attach the radiator bolts and brackets. Tighten the radiator bracket bolts to 7 ft. lbs. (10 Nm).
12. Connect the coolant reservoir overflow hose.
13. Connect the automatic transaxle cooling lines to the radiator, if equipped.
14. Connect the upper and lower radiator hoses.
15. Connect the fan motor and thermo-switch wire connector.
16. Refill the system with the proper type and quantity of coolant, check for leaks and bleed the cooling system.
17. Reconnect the negative battery cable. Fig. 8: Cooling system components — 1992–95 engines
    

Find the radiator, find the two large rubbery hoses connecting the radiator to the engine. Follow the top hose from the radiator to the engine. At the junction between the hose and the block there is a barrel or bell shaped part onto which the hose connects and which is then bolted into the engine. The thermostat is inside that bell or barrel shaped part. At least it has been there on every car I have ever seen. The thermostat blocks the flow of coolant until the engine gets warm so it has to be inside the cooling system somewhere and very near to where the coolant enters or leaves the engine.

it seems as if there is a clog in the radiator, flush out coolant system and see if this helps.usually when top hose is hot and bottom hose is cold there is a clog somewhere in system. check radiator and make sure coolant is circulating. hope this helps carl,

there is two small hose come out from reservoir. on of them(rear one) goes to coolant bypass line it is a small metal pipe goes all the way to thermostat housing other hose(front) connected to radiator.
if you lose coolant from the bottom breathing hose on reservoir you may have air in coolant system you should bleed the system.

Sounds like you might have an air pocket in the cooling system. This can develop, usually after a service, where the cooling system has to be opened to replace a water pump, thermostat, or other reason. When refilled, the air displaced by coolant has to go somewhere. In many cases, youll find that air is trapped in the highest place it can go...above the level of the radiator cap or overflow bottle. This can be a portion of the upper rad. hose, a heater hose, or a coolant line running thru various parts of the intake/throttle body area. What I do after topping up the system, is let the engine warm to normal op. temp./ W radiator cap still off. When upper hose becomes hot, you know thermostat is open. Now, if a bleeding device is not present, back off a hose clamp at the highest point in the system. Take a pair of pliers and twist the hose just enough to break the seal. You should see steam or drops escaping from your "breach". Once the steam stops and becomes all coolant, you have likely bled all air from the system. Top up radiator and coolant bottle to proper mark and close the system. (tighten your hose clamp) Check for leaks. Keep an eye on your system for a day or two, to insure no leaks are present.

Road

Caution! As with any task that involves opening the cooling system...Coolant and water can become very hot. Hot water and steam can be very dangerous. If you dont feel qualified to perform this task, let a mechanic do it!

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