Fairly straightforward procedure, but I figured after the second time I did it, I might as well do a write-up for anyone else interested in tackling it themselves.
*This water pump uses a plastic impeller. It is recommended that you use a pump with a metal impeller. Also, it is recommended at this time that you also replace your thermostat, belts, and fan clutch. I am writing this writeup for the pump only, as that’s what I did.
Some members have reported needing a special tool to hold the water pump in place while they remove the fan clutch nut. I did not need to do so, so I did not purchase the tool. They are available from a number of suppliers, including Pelican.
1: Disconnect the negative battery cable.
2: Drain the coolant from the radiator, the drain plug is on the bottom left side of the radiator.
3: Remove the fan shroud, by removing the plastic rivet on either side of the top, and lifting straight up.
4: Remove the airbox and intake assembly by loosening the clamps, unhooking the MAF sensor connector, and removing two 10mm bolts from the airbox.
5: Remove the plastic cover to the right of the radiator by removing the plastic rivet and pulling it out.
6: Remove the two coolant hoses by loosening the clamps on either end, twisting to break free, and pulling out.
7: Remove the radiator by unhooking the sensor on the right side, carefully removing the clips on the top, and lifting straight up.
8: Place the 32mm wrench on the fan clutch nut, and strike it sharply to break the bolt free. REMEMBER: THE BOLT IS REVERSE THREADED, so loosening it means turning it CLOCKWISE when viewed from the front of the car. Remove the fan and clutch as an assembly and set nut-down in a safe spot.
9: Loosen the two drive belts by loosening the center bolt and slider bolt on each, and remove the belts.
10: Remove the harmonic balancer by removing eight 13mm bolts from the center of the balancer, and tap lightly with a deadblow or mallet to remove.
There is no need to remove the large center bolt in the balancer.
11: Remove the six 10mm bolts from around the perimeter of the water pump, and tap the pump gently to break it free from the gasket, then gently pull straight forward to get the two metal coolant pipes out the back.
12: Remove the thermostat housing, thermostat, and pulley from the old water pump, and transfer to the new pump, or replace with new units.
Now, this is where you get to make a judgement call. If you were very careful, and remove the coolant pipes without damaging any o-rings, and you’re confident you can replace the pipes without damaging the o-rings, then you may begin reassembly, as outlined in step 13. If you are NOT confident, or you’d simply rather be on the safe side, then at this point, refer to my write-up on changing out the o-rings to replace them.
13: Scrape the block clean at the gasket mating surface for the water pump.
14: Making sure the coolant transfer pipes are seated firmly in the coolant manifold in the rear of the engine, gently press the new water pump into place, taking care to keep the pipes at a 90º angle to the pump and manifold in the rear.
15: Install the bolts in the locations they came out of(there are two different lengths), and snug them up finger tight.
16: Using a torque wrench, tighten each bolt to the recommended torque(I’ll update this when I get my laptop back and can look up the torque) in a criss-cross pattern.
17: The remainder of the installation is basically the reverse of removal. The harmonic balancer only fits on one way, as do the belts and hoses, so just take your time and check each step twice.
18: Add coolant! You’ll have to do this in several steps if your car is like mine, with the final addition done after the car has warmed up and been allowed to cool down again. When you get done, it’s not a bad idea to pressure test the system with a tester, available as a loaner tool from Advance Auto Parts, and Autozone, for approximately $180 and $75, respectively.
Original by Husky @ forums.bimmerforums.com