BMW Water pump replacement guide for 6 cylinder engines M50 M52 M52TU M54 E36 E39 E46 from 1992.
Remember this is only a guide, different engines in different chassis these guides might differ slightly. You can always ask us questions at tech@GermanPartsOnline.com
Remove the air funnels on top of the radiator
E36 Figure 1
E46 Figure 2
Drain the cooling system. Danger: Do Not Do This With a Hot Engine, Risk Of Burns and Scalding.
Remove the reservoir cap and drain the radiator.
There is a drain plug on the bottom of the radiator. Early style the plug unscrews.
Later style and E39 it is a 1/4 turn plug than you pull it down. Do not turn it any further than 1/4 turn. The plug will come out of the radiator, but sometimes it is hard to remove. Just work it carefully in a rocking downward motion, do not turn it back and forth because you can break the radiator itself.
E36 Figure 3 E46 Figure 4 Collect the antifreeze in a drain pan, if you are not reusing the antifreeze than take the old fluid to a recycling center. All repair shops have to take used oil, it is a federal law. They should take the used antifreeze. But be ready to pay for them to accept it because it costs them money to have it recycled. 
Do not pour it down the drain, it will eventually end up in the drinking water in most municipalities.
Remove the engine cooling fan, a special tool is required to remove the fan. It is a 32mm thin wrench and a holder wrench that goes over two of the water pump bolts to counter hold the pump. The nut on the fan clutch is left hand thread, meaning you turn it to the right to loosen and left to tighten.
Tightening torque is 36 ft lbs (which is nut much force when using the large wrench)
BMW Fan Clutch Tools The fan will only come out with the fan shroud at the same time.
After breaking loose the 32mm nut you use the fan to spin the fan and clutch off, you don't need to use the wrench anymore unless the fan clutch is no good. If the fan clutch is bad the fan will just spin and the nut will not loosen, now's the time to replace the clutch anyway. An unbalanced fan clutch will damage a new water pump real quick.
Remove the fan shroud with coolant reservoir tank (if it is attached to the shroud). E36 E39 has 2 expanding rivits, E46 has 1 expanding rivit and 1 torque bolt. After removing these the shroud and fan will pullup and out, the shroud will have hoses connected (E36 E39) at the bottom and some have a electric pump but you can meneuver the shroud over to the driver side,GENTLY.
Removing the air box helps in making room for the shroud and if you have the electric pump you will need to unplug it.
Make sure you disconnect the upper coolant bypass hose off the radiator before trying to move the reservoir bottle/shroud too far (not e46), you can break the nipple off the radiator real easy.
You will also need to remove the upper radiator hose, BE CAREFUL. The version with retaining clips, you can break the upper radiator neck wiggling the hose off. I spray a penatrating fluid around the opening of the retaining clip and let it soak in, than gently wiggle it off.
BMW Water Pump Pulley
Remove alternator drive belt. Before removing the alternator belt loosen up the four bolts that hold the water pump pulley on, 10mm bolt head.
During reassembly and after the belt is back on this is the time to make sure the pulley bolts are tight. Tightening torque is 10nm, 7.5 ft lbs.
Check the belt as well as the A/C belt. If it has cracks on the drive side now is the time to replace it.
Remove the four 10mm nuts holding in the water pump.
On the sides of the pump there are two tapped holes. 6mm diameter bolts fit in here (10mm hex head). If you have removed the thermostat use two of the removed bolts. Run the bolts into the pump until they bottom out than GENTLY tighten the bolts a little at a time, each one evenly. This will remove the pump. If you force the bolts you can break the pump.
Replace the water pump with a metal impeller pump. We also stock the high performance EMP Stewart water pumps. Search by your make and model in our store.
Before installing the new pump make sure the o-ring sealing surface is clean. Do not sand this area down. A Scotch-Brite® cleaning pad works great.
Lubricate the water pump o-ring with antifreeze and install the pump. You should be able to snap the pump into the block with out using the nuts to help if you cleaned the sealing surface good enough. Torque the four nuts to 10nm 7.5 ft lbs.
Reassemble everything in the reverse order you removed it.
Now is the time to replace the thermostat and the thermostat housing if it is plastic on your E36 cars. We have the thermostats, seals and the upgraded aluminum housings in our store.
Thermostat Housing Aluminum
If you have the electronic thermostat, now is also the time to replace it. We call them E-stats. The DME will heat up the wax pellet when it wants it to open.
I know they are expensive but those e-stats fail all the time.
They will short out and damage the wiring harness and/or the control unit.
They leak. Coolant wil actually wick up the wire harness and destroy the DME
They also stick open.
If you have a scan tool you can see if you have a error code for 'map cooling' this is that thermostat. We also carry these e-stats in our store.
When installing the fan shroud make sure it is seated in all it's holders correctly, and that the bypass hose is not hanging down the backside of the radiator, the fan will cut the hose up real fast.
After reassembly you need to bleed the cooling system.
Turn on the key but DO NOT START THE ENGINE.
Move the temp on the climate control to full heat (dual zone unit do both), A/C button off, low fan speed. This opens the mono valves.
Depending upon chassis, open the bleeder screws.E36 engine the bleeder in on the reservoir tank.
E46 there is one bleeder on the upper radiator hose near the resevior tank.
E39 there are two bleeders, one on the reservoir tank and one on the upper radiator hose near the thermostat or in the thermostat housig itself.
E36 Bleeder Screw
E46 Upper Radiator Hose
E39 Bleeder Screw E39 Upper Radiator Hose
Fill up the reservoir tank with a 50/50 mix of antifreeze and distilled water SLOWLY. Fill until there are no more air bubbles coming out of the bleeder(s).
Put the cap back on.
Check for leaks.
I like to start the engines, rev them up to about 4000 rpm about 6 times. Shut off the engine (before it gets hot. Remove the reservoir cap (DANGER RISK OF SCALDING ONLY OPEN WHEN COLD) and make sure the antifreeze is just above the cold mark.
After driving the car and the engine cools down check the level again, sometimes air bubbles get trapped in the engine and will not come out until you drive the engine.
Again check for leaks.
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