Have replaced thermostat and housing sparkplugs and wire kit water pump and serpentine belt as well as tensioner bar kit and upper radiator hose and am still overheating. I am trying to find a visual of my radiator and maybe do a complete radiator flush. Also should I use full antifree/coolant or 50/50 after I have done the complete radiator flush? Please advise

I don't have a diagram. Here are the steps.
1) disconnect negative battery wire..
2) remove serpentine belt
3) remove upper heater hose and thermostat housing; leave thermostat in place
4) remove plate from in front of the power steering pump, the lower bolt is one of three of the alternator bolts.
5) remove all 5 bolts from the PS pump bracket - 2 are by the thermostat housing. Remove the bracket.
6) move the PS pump off to the side out of your way.
7) Remove the long bolt from the alternator you can now see. There is one more alternator bolt at the top which will allow you to remove the idler pulley bracket with the serpentine tensioner. This idler bracket and the tensioner bracket are sizeable, so you have to understand the volume of stuff you are removing.
8) Unhook the alternator wire and with some patience, if you have any left, you can squeeze the alternator out.
This procedure assumes you have the ability to do the serpentine belt removal and refitting, and you will need 12mm sockets/wrenches to do the rest. The t-stat housing uses the torx head screws, so you need that as well.

Alway pick the thermostat with "fail-safe" relief. Look for a float like pressure relief port.

The low tech method to prevent trap air pocket is to drive the car onto an oil ramp (or hill) then fill coolant slowly.

The Water Pump on the BMW 745 is Serpentine Belt Driven, you have to take the Serpentine Belt Off along with the UPPER Radiator Schroud to give you enough clearance to do this procedure.

Be VERY CAREFUL that you do not puncture the Radiator....

check your vacume lines to make sure they are in the correct position

For 2008, the water pump is not driven by the timing belt. Also, the motor does not have to be lifted. The haynes manual says to pull the ac unit, alternator, and drive axle, which is not required. Also, you do not have to lift the motor. I saw this on the net, which is incorrect for 2008 Sienna.1) Drain the system of anti-freeze2) take-off the passenger side front tire to get to the access panel, using a jack stand on the body.2) remove the access panel, and you should see most of the bottom bolts of the water pump3) do not remove the serpentine belt just yet, crack the bolts holding the water pump pulley, but do not remove them. If you remove the belt, you will be fighting against yourself to unloosen them later. 4) remove the serpentine belt (see youtube - a guy has a video of this piece which is easy)5) remove the top engine mount, which has about 4 bolts6) remove the aluminum bracket surrounding the thermostat housing which has about 7, and yes, some are long. 7) remove the thermostat housing, and disconnect the 3/4 hose in the back8) remove the belt tensioner pulley, by wrenching clockwise. 9) remove the 2nd serpentine pulley10) remove the 4 bolts for the water pump pulley11) remove the 16 bolts of the water pump12) reverse your order, and you should be good to go. Also, I replaced mythermostat, when the housing was out. Good Luck !

If that is a 6 cylinder, there is no belt, its a chain. Water pump is the leaking part.

Water Pump REMOVAL & INSTALLATION 3.5L Engine

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Partially drain the cooling system.
3. Remove or disconnect the following:
   • Water pump pulley bolts, loosen but do not remove at this time
   • Drive belt
   • Idler pulley
   • Water pump pulley
   NOTE: The water pump is attached to the engine with both long and short bolts, be sure to note their locations.
   • Water pump and discard the gasket
   NOTE: Note the locations of the 5 long bolts.
   
4. Clean the water pump mounting surface. Fig. 1: Be sure to install the 5 long water pump bolts in the correct locations - 3.5L engine
   Fig. 2: Water pump mounting - 3.5L engine
   To install: NOTE: Be sure to install the 5 long bolts in the proper locations.
   
5. Install or connect the following:
   • Water pump using a new gasket. Torque the bolts to 124 inch lbs. (14 Nm).
   • Water pump pulley
   • Idler pulley. Torque the bolt to 37 ft. lbs. (50 Nm).
   • Drive belt
6. Refill the cooling system.
7. Start the engine and check for leaks.

3.8L Engines

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Disconnect the negative battery cable.
3. Drain the cooling system.
4. Remove or disconnect the following:
   • Serpentine belt
   • Heater and bypass hoses from the water pump
   • Water pump pulley
   NOTE: The long bolt can be removed by aligning the bolt head with the frame rail hole.
   
5. Install an engine support fixture.
6. Remove or disconnect the following:
   • Torque axis mount
   • Water pump and discard the gasket
   To install: Fig. 3: Exploded view of the water pump and mounting bolt locations - 3.8L engines
   
   
7. Thoroughly clean all the sealing surfaces.
8. Apply a thin bead of sealer around the outside edge of the water pump
9. Install or connect the following:
   • New gasket
   • Water pump. Torque the inlet and outlet side bolts to 29 ft. lbs. (39 Nm) and the remaining bolts to 97 inch lbs. (11 Nm).
   • Torque axis mount
10. Remove the support fixture.
11. Install or connect the following:
    • Water pump pulley
    • Water pump hoses
    • Serpentine belt
    • Water pump pulley bolts. Torque the bolts to 115 inch lbs. (13 Nm).
    • Negative battery cable
12. Refill the cooling system.
13. Start the vehicle and check for proper operation.

4.0L Engine

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Disconnect the negative battery cable.
3. Drain the cooling system.
4. Remove or disconnect the following:
   • Air inlet duct
   • Water pump drive belt cover
   • Water pump drive belt
   • Lower radiator hose and bypass hose
   • Thermostat housing from the water pump housing
   • Water pump from the water pump housing, by turning the locking ring with a Water Pump Remover/Installer tool J-38816
   To install: Fig. 4: Exploded view of the water pump housing and water pump - 4.0L engine
   
   
5. Install or connect the following:
   • Water pump, seat the locking ring
   • Thermostat housing to the water pump housing
   • Lower radiator hose and coolant bypass hose
   • Drive belt and drive belt cover
   • Air inlet duct
   • Negative battery cable
6. Refill and bleed the cooling system.

1 disconect neg.battery cable 2 drain the cooling system 3 remove air intake tube from filter housing to throttle body 4 remove top half of fan shroud 5 remove the serpentine belt 6 use a strap wrench to prevent the waterpump pulley from turning while turning the fan clutch in the counterclockwise direction. 7 remove fan and set aside 8 remove belt tensioner 9 remove hoses from water pump 10 remove 6 bolts, 3 on either side and remove the water pump. 11 remove the thermostat housing from the old pump and install on the new one. 12 re assemble in reverse order. make sure the mating surface of the engine block where the pump bolts on is clean and free of old gasket material before installing new pump and gaskets. When assembled fill cooling system, start engine and let idle untill thermostat opens and engine reaches operating temp.KEEP WATER LEVEL FULL. After a test drive recheck the coolant level, and you are done.

www.autozone.com

They can get all the parts. They also provide haynes repair manuals, any special tools (probably not required for this vehicle) and any special disassembly instructions.

I hope this helps.

Yes,but only if you want to remove the complete water pump including the thermostat housing. If you only want to replace the water pump(front section only) the part that leaks water from the small hole in the housing behind the pulley you only have to remove the 10mm bolts running in a circle!!

Regards
Phillip