I went to change the thermostat. on 98 Olds Sillouet When I removed the throttle body I found oil and water in the upper intake manifold Also I did not find any water on the dipstick. Any ideas?

To remove a fuel injector or injectors you must remove the fuel supply rail that sits over them. Here is how you do that for both engine options, Turbo and non Turbo..

Removal & Installation

Except Turbocharged Models

WARNING Release fuel system pressure before servicing fuel system components. Service vehicles in well ventilated areas and avoid ignition sources. Never smoke while servicing the vehicle. This may result in personal injury or *****.

1. Release fuel system pressure.
2. Remove the air cleaner lid, disconnect the inlet air temperature sensor and makeup air hose.
3. Remove the negative battery cable.
4. Remove the engine cover or throttle control shield if equipped.
   NOTE Wrap shop towels around hose to catch any gasoline spillage.
5. Disconnect fuel supply tube from rail.
6. Remove the Intake Manifold, refer to the Engine section.
7. Disconnect electrical connectors from fuel injectors.
8. Remove bolts holding fuel rail.
9. Remove the fuel rail and injectors.
10. Remove the injectors from the fuel rail.

To install:

1. Install injectors to the fuel rail.
2. Apply a light coating of clean engine oil to the O-ring on the nozzle end of each injector.
3. Insert fuel injector nozzles into openings in intake manifold. Seat the injectors in place. Tighten fuel rail bolts to 170-230 inch lbs. (19.5-25.5 Nm).
4. Attach electrical connectors to fuel injectors.
5. Connect fuel supply tube to fuel rail. Refer to Quick Connect Fittings in the Fuel Delivery section
6. Install Intake Manifold, refer to the Engine section.
7. Install the engine cover or throttle control shield if equipped.
8. Install the negative battery cable.
9. Install the air cleaner lid, connect the inlet air temperature sensor and makeup air hose. Tighten air inlet tube clamps to 20-30 inch lbs. (2-4 Nm).

Turbocharged Models

WARNING Release fuel system pressure before servicing fuel system components. Service vehicles in well ventilated areas and avoid ignition sources. Never smoke while servicing the vehicle. This may result in personal injury or *****.

1. Release the fuel system pressure.
2. Disconnect the negative battery cable.
3. Disconnect the throttle body inlet hose and remove from throttle body.
4. Disconnect the purge hose from the throttle body.
5. Unlock and disconnect the electrical connection at the throttle body.
6. Remove the throttle control shield .
7. Remove the throttle and speed control cables from the throttle body.
8. Remove the cables from the throttle body bracket.
9. Unlock and disconnect the MAP sensor electrical connector.
10. Remove the vacuum lines from the rear of the intake manifold.
11. Remove the 5 bolts from the front of the intake manifold.
12. Remove the 2 bolts from the rear of the intake manifold.
13. Remove the intake manifold. Cover the lower intake manifold openings.
14. Drain the Coolant system.
15. Move the upper radiator hose clamp, so that the hose can be rotated up and out of the way.
16. Remove the 2 small hoses from the thermostat housing.
17. Remove the 2 bolts from the thermostat housing and rotate the assembly up and out of the way.
    NOTE Wrap shop towels around hose to catch any gasoline spillage.
18. Disconnect the fuel line from the fuel rail.
19. Unlock and disconnect the electrical connectors from the fuel injectors.
20. Remove the wiring harness from the fuel rail.
21. Remove the 2 bolts from the fuel rail.
22. Remove the fuel rail and injectors from the intake manifold.

To install:

1. Install the fuel injectors to the fuel rail.
2. Apply a light coating of clean engine oil to the O-ring on the nozzle end of each injector.
3. Insert fuel injector nozzles into openings in intake manifold. Seat the injectors in place.
4. Install the 2 bolts to the fuel rail. Tighten fuel rail bolts to 170-230 inch lbs. (19.5-25.5 Nm).
5. Install the wiring harness to the fuel rail.
6. Connect and lock the electrical connectors to the fuel injectors.
7. Connect the fuel line to the fuel rail.
8. Rotate the assembly back into place and install the 2 bolts to the thermostat housing tighten to 110 inch lbs. (12.5 Nm).
9. Move the upper radiator house clamp back into place.
10. Install the 2 small hoses to the thermostat housing.
11. Fill the Coolant system.
12. Install the intake manifold.
13. Install the 2 bolts to the rear of the intake manifold tighten to 250 inch lbs. (28 Nm).
14. Install the 5 bolts to the front of the intake manifold and tighten to 250 inch lbs. (28 Nm).
15. Install the vacuum lines to the rear of the intake manifold.
16. Connect and lock the MAP sensor electrical connector.
17. Install the cables to the throttle body bracket.
18. Install the throttle and speed control cables to the throttle body.
19. Install the throttle control shield.
20. Connect and lock the electrical connections at the throttle body.
21. Connect the purge hose to the throttle body.
22. Connect the throttle body inlet hose to the throttle body and tighten clamps to 20-30 inch lbs. (2-4 Nm).
23. Connect the negative battery cable.
24. Use the DRB® scan tool ASD Fuel System Test to pressurize the fuel system. Check for leaks.

Removal & Installation

Except Turbocharged Models

WARNING Release fuel system pressure before servicing fuel system components. Service vehicles in well ventilated areas and avoid ignition sources. Never smoke while servicing the vehicle. This may result in personal injury or *****.

1. Release fuel system pressure.
2. Remove the air cleaner lid, disconnect the inlet air temperature sensor and makeup air hose.
3. Remove the negative battery cable.
4. Remove the engine cover or throttle control shield if equipped.
   NOTE Wrap shop towels around hose to catch any gasoline spillage.
5. Disconnect fuel supply tube from rail.
6. Remove the Intake Manifold, refer to the Engine section.
7. Disconnect electrical connectors from fuel injectors.
8. Remove bolts holding fuel rail.
9. Remove the fuel rail and injectors.
10. Remove the injectors from the fuel rail.

To install:

1. Install injectors to the fuel rail.
2. Apply a light coating of clean engine oil to the O-ring on the nozzle end of each injector.
3. Insert fuel injector nozzles into openings in intake manifold. Seat the injectors in place. Tighten fuel rail bolts to 170-230 inch lbs. (19.5-25.5 Nm).
4. Attach electrical connectors to fuel injectors.
5. Connect fuel supply tube to fuel rail. Refer to Quick Connect Fittings in the Fuel Delivery section
6. Install Intake Manifold, refer to the Engine section.
7. Install the engine cover or throttle control shield if equipped.
8. Install the negative battery cable.
9. Install the air cleaner lid, connect the inlet air temperature sensor and makeup air hose. Tighten air inlet tube clamps to 20-30 inch lbs. (2-4 Nm).

Turbocharged Models

WARNING Release fuel system pressure before servicing fuel system components. Service vehicles in well ventilated areas and avoid ignition sources. Never smoke while servicing the vehicle. This may result in personal injury or *****.

1. Release the fuel system pressure.
2. Disconnect the negative battery cable.
3. Disconnect the throttle body inlet hose and remove from throttle body.
4. Disconnect the purge hose from the throttle body.
5. Unlock and disconnect the electrical connection at the throttle body.
6. Remove the throttle control shield .
7. Remove the throttle and speed control cables from the throttle body.
8. Remove the cables from the throttle body bracket.
9. Unlock and disconnect the MAP sensor electrical connector.
10. Remove the vacuum lines from the rear of the intake manifold.
11. Remove the 5 bolts from the front of the intake manifold.
12. Remove the 2 bolts from the rear of the intake manifold.
13. Remove the intake manifold. Cover the lower intake manifold openings.
14. Drain the Coolant system.
15. Move the upper radiator hose clamp, so that the hose can be rotated up and out of the way.
16. Remove the 2 small hoses from the thermostat housing.
17. Remove the 2 bolts from the thermostat housing and rotate the assembly up and out of the way.
    NOTE Wrap shop towels around hose to catch any gasoline spillage.
18. Disconnect the fuel line from the fuel rail.
19. Unlock and disconnect the electrical connectors from the fuel injectors.
20. Remove the wiring harness from the fuel rail.
21. Remove the 2 bolts from the fuel rail.
22. Remove the fuel rail and injectors from the intake manifold.

To install:

1. Install the fuel injectors to the fuel rail.
2. Apply a light coating of clean engine oil to the O-ring on the nozzle end of each injector.
3. Insert fuel injector nozzles into openings in intake manifold. Seat the injectors in place.
4. Install the 2 bolts to the fuel rail. Tighten fuel rail bolts to 170-230 inch lbs. (19.5-25.5 Nm).
5. Install the wiring harness to the fuel rail.
6. Connect and lock the electrical connectors to the fuel injectors.
7. Connect the fuel line to the fuel rail.
8. Rotate the assembly back into place and install the 2 bolts to the thermostat housing tighten to 110 inch lbs. (12.5 Nm).
9. Move the upper radiator house clamp back into place.
10. Install the 2 small hoses to the thermostat housing.
11. Fill the Coolant system.
12. Install the intake manifold.
13. Install the 2 bolts to the rear of the intake manifold tighten to 250 inch lbs. (28 Nm).
14. Install the 5 bolts to the front of the intake manifold and tighten to 250 inch lbs. (28 Nm).
15. Install the vacuum lines to the rear of the intake manifold.
16. Connect and lock the MAP sensor electrical connector.
17. Install the cables to the throttle body bracket.
18. Install the throttle and speed control cables to the throttle body.
19. Install the throttle control shield.
20. Connect and lock the electrical connections at the throttle body.
21. Connect the purge hose to the throttle body.
22. Connect the throttle body inlet hose to the throttle body and tighten clamps to 20-30 inch lbs. (2-4 Nm).
23. Connect the negative battery cable.
24. Use the DRB® scan tool ASD Fuel System Test to pressurize the fuel system. Check for leaks.

Oil in most cases is normal, it circulates, in the recycled emissions, water could come from the rain, if intake pipe is low to the ground it can suck it in, if you have an aftermarket Turbo, it definitely comes from the air intake,

Follow the upper rad hose to where it meets the engine.The hose is attached to the thermostat housing,just tucked under the exhaust crossover pipe.

Yes you do, the following info explains the necessary procedure.



Click here to enlarge image.

Click here to enlarge image.

1. Properly relieve the fuel system pressure.
2. Disconnect the negative battery cable. Place a clean drain pan under the radiator, open the drain **** and drain the cooling system.
3. Remove the air cleaner assembly and the fuel injector sight shield.
4. Disconnect the cables from the throttle body and mount bracket.
5. Remove the coolant recovery reservoir.
6. Remove the inner fender electrical cover on the right side.
7. Remove the right rear crossover pipe heat shield.
8. Disconnect the fuel lines from the fuel rail and from the cable bracket.
9. Remove the alternator and brace.
10. Remove the throttle body cable mounting bracket with the vacuum lines and disconnect the vacuum lines.
11. Tag and detach the electrical connections at the throttle body and both banks of fuel injectors.
12. Disconnect the vacuum hoses from the canister purge solenoid valve and transaxle module and intake connection.
13. Unbolt the power steering pump and move forward. DO NOT disconnect the fluid lines.
14. Tag and disconnect the spark plug wires position lay aside.
15. Disconnect the coolant bypass hose from the intake manifold.
16. Remove the solenoid valve mounting bracket and power steering support brace from the intake manifold.
17. Disconnect the heater pipes from the intake and front cover.
18. Remove the alternator support brace from the intake.
19. Disconnect the upper radiator hose from the housing.
20. Remove the thermostat housing and thermostat from the intake.
21. Detach the electrical connector from the temperature sensor and sensor switch.
22. Unfasten the intake manifold bolts, then remove the manifold as an assembly. Remove and discard the gaskets.
23. If separating the upper manifold from the lower, proceed as follows:
24. Remove the fuel rail and fuel injectors.
25. Detach the coolant sensor switch.
26. Remove the manifold end cap cover.
27. Remove the upper intake manifold and throttle body assembly from the lower manifold. Remove and discard the gaskets. To install:
    
28. Thoroughly clean all gasket mating surfaces.
29. If replacing the upper manifold, proceed as follows:
30. Apply a 1⁄16 in. bead of Loctite® Instant Gasket Eliminator 51845 or equivalent to the lower manifold mating surface. Make sure to circle all bolt holes.
31. Carefully lower the upper manifold and throttle body assembly onto the lower manifold.
32. Tighten the upper manifold retaining bolts to 19 ft. lbs. (26 Nm).
33. Install the manifold end cap cover and the coolant sensor switch.
34. Install the fuel injectors and rail to the manifold assembly.
35. Clean the mating surfaces and install the intake manifold gaskets and seals. Apply sealer to the ends of the of the intake manifold seals.
36. Position the intake manifold and apply a suitable thread lock compound to the bolt threads. Tighten the retaining bolts to 88 inch lbs. (10 Nm), twice, in the sequence shown in the accompanying figure.
37. Attach the electrical connector to the temperature sensor and sensor switch.
38. Install the thermostat housing and thermostat with a new gasket.
39. Connect the alternator support brace to the intake.
40. Install the solenoid valve mounting bracket and power steering support brace to the intake manifold.
41. Connect the heater pipes to the intake and front cover.
42. Attach the coolant bypass hose to the intake manifold.
43. Install the power steering pump support bracket and tighten to 37 ft. lbs. (50 Nm).
44. Install the spark plug wires on both sides.
45. Install the belt tensioner pulley and tighten to 33 ft. lbs. (45 Nm).
46. Install the power steering pump.
47. Connect the vacuum hoses to the canister purge solenoid valve and transaxle module and intake connection.
48. Attach the electrical connections at the throttle body and both banks of fuel injectors.
49. Install the alternator and brace.
50. Connect the throttle body cable mounting bracket with the vacuum lines.
51. Install the right rear crossover pipe heat shield.
52. Install the cables to the throttle body.
53. Connect the fuel lines to the fuel rail and mount bracket.
54. Install the inner fender electrical cover on the right side.
55. Install the coolant recovery reservoir and upper radiator hose. Fill the cooling system.
56. Install the air cleaner assembly and the fuel injector sight shield.
57. Connect the negative battery cable.

You didn't post the size of your engine so please pick the appropriate one:

3.8L

1. Relieve the fuel system pressure.
   
2. Drain the cooling system.
   

1. Remove or disconnect the following:
2. Negative battery cable
   

• Supercharger
  
• Thermostat housing
  
• Exhaust Gas Recirculation (EGR) tube at the intake manifold
  
• Engine Control Temperature (ECT) sensor
  
• Intake manifold
  

To install:

1. Install or connect the following:
   
   • Intake manifold with new gaskets. Torque the bolts, working from the center out, to 11 ft. lbs. (15 Nm).
     
   • ECT sensor connector
     
   • EGR tube to the intake manifold
     
   • Thermostat housing
     
   • Supercharger
     
   • Negative battery cable
     
2. Refill and bleed the cooling system.
   
3. Run the engine and check for leaks and proper engine operation.
   

4.6L
4.6L Engine

1. Remove the brake booster hose from the throttle body.
   
2. Remove the fuel pressure regulator vacuum tube from the fuel pressure regulator and the water crossover.
   
3. Remove the PCV fresh air feed tube from the camshaft cover and the throttle body.
   
4. Remove the PCV dirty air tube from the PCV orifice in the right camshaft cover and from the intake manifold.
   
5. Disconnect the fuel injector electrical connectors from the fuel injectors.
   
6. Remove the fuel injector wiring harness.
   
7. Remove the fuel rail bracket nut from the engine lift bracket.
   
8. Remove the fuel rail studs.
   
9. Lift and remove the fuel rail with injectors.
   
10. Loosen the plenum duct clamp in order to remove the intake manifold.
    
11. Remove the intake manifold bolts.
    
12. Remove the intake manifold.
    

To install:

1. Install the intake manifold, fitting the plenum duct over the intake manifold duct.
   
2. Loosely install the intake manifold bolts.
   

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Intake manifold torque sequence-4.6L engine

2. Tighten the intake manifold bolts in sequence. Tighten the intake manifold bolts to 89 inch lbs. (10 Nm).
   
4. Tighten the plenum duct clamp to the intake manifold. Tighten the plenum duct clamp to 24 inch lbs. (2.75 Nm).
   
5. Inspect the fuel injector O-rings. Ensure the fuel injector O-rings are not missing, misaligned or damaged. Replace the O-rings if necessary.
   
6. Lubricate the intake manifold fuel injector bores with light mineral oil (GM P/N 9981704), clean engine oil, or equivalent.
   
7. Install the fuel rail with fuel injectors as an assembly.
   
8. Install the fuel rail studs. Tighten the fuel rail studs to 80 inch lbs. (9 Nm).
   
9. Install the fuel rail bracket nut to the engine lift bracket. Tighten the fuel rail bracket nut to 89 inch lbs. (10 Nm).
   
10. Install the fuel injector wiring harness.
    
11. Connect the fuel injector electrical connectors to the fuel injectors.
    
12. Install the PCV dirty air tube to the PCV orifice in the right camshaft cover and to the intake manifold.
    
13. Install the PCV fresh air feed tube to the camshaft cover and the water crossover.
    
14. Install the fuel pressure regulator vacuum tube to the fuel pressure regulator and the throttle body.
    
15. Install the brake booster hose to the throttle body.
    

3.8L Engine (most common) Upper Intake Manifold To Remove:

1. Drain the cooling system.
2. Remove or disconnect the following:
   • Negative battery cable.
   • Fuel injector sight shield.
   • Air cleaner intake duct.
   • Right spark plug wires from the ignition control module and reposition.
3. Relieve the fuel pressure.
4. Remove or disconnect the following:
   • Fuel rail assembly.
   • Brake booster hose from the vacuum source manifold in the upper intake manifold.
   • Exhaust Gas Recirculation Valve (EGR) wiring harness heat shield nut, bolt and the EGR heat shield.
   • Throttle body support bracket upper bolt.
5. Disconnect the electrical connectors from the following:
   • EVAP purge solenoid
   • Throttle Position (T/P) sensor
   • Idle Air Control (IAC) valve
   • Manifold Absolute Pressure (MAP) sensor
   • Mass Air Flow (MAF) sensor
   • EVAP purge solenoid vacuum line from the throttle body.
   • Accelerator and the cruise control cables with the bracket from the throttle body.
6. Remove or disconnect the following:
   • Upper intake manifold bolts and stud.
   • Clean the upper intake manifold bolt threads.
7. Remove or disconnect the following:
   • Upper intake manifold by lifting the back of the intake and sliding the manifold forward from the throttle body support bracket.
   • Upper-to-lower intake manifold carrier gasket from the upper intake manifold.
8. If the upper intake manifold is being replaced, remove the following:
   • Throttle body assembly.
   • Manifold Absolute Pressure (MAP) sensor.
   • Positive Crankcase Ventilation (PCV) valve.
   • Vacuum source manifold.

Upper intake manifold bolt torque sequence (3.8L engine)

To Install:

1. If the manifold was replaced, install or connect the following:
   • Vacuum source manifold.
   • Positive Crankcase Ventilation (PCV) valve.
   • Manifold Absolute Pressure (MAP) sensor.
   • Throttle body assembly.
   • Upper-to-lower intake manifold carrier gasket to the upper intake manifold.
2. Carefully place the upper intake manifold onto the lower intake manifold. Ensure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold. NOTE: Apply thread lock compound, to the bolt threads before assembly.
   
3. Install or connect the following:
   • Upper intake manifold. Tighten the upper intake manifold bolts in sequence to 89 in lbs (10 Nm)
   • Accelerator and the cruise control cables with the bracket to the throttle body.
   • EVAP purge solenoid vacuum line to the throttle body.
4. Connect the electrical connectors to the following:
   • Mass Air Flow (MAF) sensor
   • Manifold Absolute Pressure (MAP) sensor
   • Idle Air Control (IAC) valve
   • Throttle Position (T/P) sensor
   • EVAP purge solenoid
5. Install or connect the following:
   • Throttle body upper support bracket bolt. Tighten the bolt to 89 in lbs (10 Nm)
   • EGR valve wiring harness heat shield, nut and the bolt. Tighten the nut and the bolt to 89 in lbs (10 Nm)
   • Brake booster hose to the vacuum source manifold.
   • Fuel rail assembly.
   • Right spark plug wires.
   • Air cleaner intake duct.
   • Fuel injector sight shield.
6. Connect the negative battery cable.
7. Fill the cooling system.
8. Inspect for fluid or vacuum leaks.

Lower Intake Manifold (W/O Supercharger) To Remove:

1. Remove or disconnect the following:
   • Upper intake manifold.
   • Generator brace.
   • Drive belt tensioner with the mounting bracket and the heater water bypass inlet pipe.
   • Exhaust gas recirculation EGR outlet pipe bolt from the lower intake manifold.
   • Radiator inlet hose from the water outlet housing.
   • ECT sensor electrical connector.
   • Right upper engine mount strut bracket.
   • Generator brace bracket bolts.
   • Generator brace bracket.
   • Lower intake manifold bolts.
   • Lower intake manifold.
   • Lower intake manifold seals.
   • Lower intake manifold gaskets.
2. If replacing the lower intake manifold, Remove or disconnect:
   • Water outlet housing bolt and stud
   • Water outlet housing
   • Gasket and the thermostat.
   • ECT sensor.
3. Inspect the flatness of inlet flanges.
4. Clean the intake manifold mating surfaces.
5. Clean the intake manifold bolts and bolt holes of adhesive compound.

To Install:

1. If removed, install the ECT sensor.
   • Tighten the ECT sensor to 18 ft. lbs. (25 Nm)
2. If removed, install the thermostat, the gasket, and the water outlet housing.
3. If removed, install the water outlet housing bolt and the stud.
   • Tighten the bolt and stud to 20 ft. lbs. (27 Nm)
4. Install or connect the following:
   • Lower intake manifold gaskets. NOTE: Apply sealer GM P/N 12346286 (Canadian P/N 10953472) or equivalent to the ends of the intake manifold seals.
     
   • Lower intake manifold seals.
   • Lower intake manifold.
   • Lower intake manifold bolts.
   NOTE: Apply thread lock compound GM P/N 12345382 (Canadian P/N 10953489) or equivalent to the two hidden bolts and ensure they are installed.
   
5. Tighten the lower intake manifold bolts in sequence to 11 ft. lbs. (15 Nm)
   
   
6. Install or connect the following:
   • Generator brace bracket.
   • Generator brace bracket bolts. Tighten the bolts to 37 ft. lbs. (50 Nm)
   • Right upper engine mount strut bracket.
   • ECT sensor electrical connector.
   • Radiator inlet hose to the water outlet housing.
   • EGR outlet pipe to the lower intake manifold.
   • EGR outlet pipe bolt to the lower intake manifold. Tighten the bolt to 21 ft. lbs. (29 Nm)
   • Drive belt tensioner.
   • Generator brace.
   • Upper intake manifold.
7. Inspect for leaks.

Lower Intake Manifold (W/ Supercharger) To Remove:

1. Disconnect the negative battery cable.
2. Drain the cooling system.
3. Remove the supercharger.
4. Remove the thermostat housing.
5. Remove the EGR pipe at the intake manifold.
6. Disconnect the electrical connection at the temperature sensor.
7. Remove the intake manifold and gaskets.

NOTE: The coolant bypass tube will release from the intake manifold when the manifold is removed.
To Install:

1. Clean the gasket sealing surfaces.
2. Install the intake manifold gaskets.
3. Align the coolant bypass tube with the opening in the intake manifold and install the manifold. Tighten the bolts to 11 lb ft (15 Nm).
4. Install the electrical connector to the temperature sensor.
5. Install the EGR pipe to the intake manifold.
6. Install the thermostat housing.
7. Install the supercharger.
8. Fill the cooling system.
9. Connect the negative battery cable.

Drain radiator. Remove upper rad hose from thermostat housing. Disconnect air intake hose from throttle body. Remove throttle body from upper intake manifold, disconnecting the 2 rubber hoses to the heater line. You may also need to disconnect the fuel line. Remove the exhaust crossover heat shield and loosen the crossover pipe from both exhaust manifolds but don't remove crossover completely. You should have access to the 2 thermostat housing bolts, remove upper bolt but just loosen the lower one about a half inch. Pull the housing out and up from the intake manifold to access the thermostat. Clean the mating surfaces with a gasket remover. replace thermostat, apply a light coating of rtv sealant to both sides of the new gasket. Replace thermostat housing with the gasket to the intake manifold. Apply some rtv to the bolt threads before reattaching housing. Tighten bolts snugly but do not over tighten. Tighten exhaust crossover and reattach the heat shield. Install throttle body attaching the 2 little hoses at the bottom, its a good time to replace these hoses and clamps. Depending on the condition of the throttle body gasket you may need to replace it also. Reconnect the fuel line (if disconnected) Reconnect air intake hose to throttle body. Reattach the upper rad hose to housing. Fill rad with coolant 50/50 mix with water (make sure to use the same type antifreeze that is in the system, they say you can mix green with red but I wouldn't recommend) Leave rad cap off start the car and let it warm up until you can see the coolant circulating and ad coolant as necessary until full. Now there is going to be some air in the system that you need to bleed out. There are 2 bleeders on this system, 1 is on the top of the thermostat housing, and the other is on the metal heater line on top of the water pump (the one that goes across the front of the engine and around under the throttle body that the two little hoses attach to) Bleed the one on the housing first (its the lower one) open it until fluid comes out then tighten it. Then move to the 1 on the heater line(above water pump) loosen it until fluid comes out the re-tighten. Fill recovery tank to fill line replace the rad cap and take it for a ride, watching the temp gage closely. If the temp goes higher than normal than there is probably more air in the system. you'll have to bleed it again.
This is a very labor intensive procedure and I do recommend buying or checking a service manual out from your local library. I've done these in the past and to be honest I just have the dealer do it now. A system flush and thermostat replacement was around $230 the last time I had it done, but it comes with a warranty. And you wont have to rent or buy a fuel line disconnect tool if you end up having to disconnect it. These are the hardest thermostats I've ever replaced.

Bonneville, LeSabre, Park Avenue 2000-2005 Intake Manifold - Removal & Installation

3.8L Engine
VIN 1 Engine

1. Before servicing the vehicle, refer to the Precautions section.
2. Relieve the fuel system pressure.
3. Drain the cooling system.
4. Remove or disconnect the following:
   Negative battery cable Supercharger Thermostat housing Exhaust Gas Recirculation (EGR) tube at the intake manifold Engine Control Temperature (ECT) sensor Intake manifold

To install:

1. Install or connect the following:
   Intake manifold with new gaskets. Torque the bolts, working from the center out, to 11 ft. lbs. (15 Nm). ECT sensor connector EGR tube to the intake manifold Thermostat housing Supercharger Negative battery cable
2. Refill and bleed the cooling system.
3. Run the engine and check for leaks and proper engine operation.

VIN K Engine

1. Before servicing the vehicle, refer to the Precautions section.
2. Disconnect the negative battery cable.
3. Drain the cooling system.
4. Relieve the fuel system pressure.
5. Remove or disconnect the following:
   Fuel injector sight shield Air inlet duct Spark plug wires from the right side Manifold Absolute Pressure (MAP) sensor Vacuum lines from the intake manifold Fuel lines Fuel injector electrical connectors Fuel regulator vacuum line Fuel rail from the intake manifold Exhaust Gas Recirculation (EGR) heat shield Throttle cable bracket from the cylinder head mounting bracket and the throttle body cables Throttle body support bracket Upper intake plenum and gasket Thermostat housing Electrical connector from the Engine Coolant Temperature (ECT) sensor Drive belt tensioner assembly EGR valve outlet pipe Lower intake manifold
   
   
   Fig. Exploded view of the intake manifold and related components-3.8L (VIN K) engine
   

To install:



Fig. Upper intake manifold torque sequence-3.8L (VIN K) engine



Fig. Lower intake manifold torque sequence-3.8L (VIN K) engine

1. Install or connect the following:
   Intake manifold using new manifold gaskets. Torque the bolts in sequence to 11 ft. lbs. (15 Nm); then, re-torque to 11 ft. lbs. (15 Nm). EGR valve outlet pipe Drive belt tensioner assembly. Torque the tensioner bolts to 37 ft. lbs. (50 Nm). Electrical connector to the ECT sensor Thermostat housing Upper intake plenum. Torque the intake plenum bolts to 88 inch. lbs. (10 Nm). Throttle body support bracket Throttle cable bracket to the cylinder head mounting bracket and the cables to the throttle body lever EGR heat shield Fuel rail. Torque the fuel rail bolts to 88 inch. lbs. (10 Nm). Fuel lines Fuel regulator vacuum line Fuel injector electrical connectors Vacuum lines to the intake manifold MAP sensor Spark plug wires Fuel injector sight shield and air inlet duct Negative battery cable
2. Refill and bleed the cooling system.
3. Run the engine and check for leaks and proper engine operation.

Hope this help (remember rated this).