E46 Water Pump Replacement
These instructions are only a guide for replacing the water pump. Please read through all the instructions before attempting to install on your own. I take no responsibilities for any inaccuracies or problems/damage /injuries you may encounter from using these instructions. Please consult your shop manual.
My thermostat was failing so I decided to replace my water pump at the same time. My car has over 100k miles and I thought I'd do some preventative maintenance. The initial steps are the same between the thermostat and the water pump.
Water Pump (Part # 11517527910) (Figure A)
(Check BMW for latest part #)
8mm allen socket
(2) M6 bolts to extract Water Pump (if replacing thermostat, you can use the 10mm bolts from the thermostat)
Pan to catch the old Coolant
For Cars with Automatic Transmissions
You need Clutch Fan removal tools. This is not covered in this DIY
1. Raise front of the car and remove underbody splash guard. Its held in place by screws and some plastic plugs. Lower car after done. Drain coolant.
2. Remove intake shroud. 4 plastic expanding rivets. (Figure B) Note: newer cars only have 3.
Note: On Automatic Transmission cars, you need to remove the clutch fan at this point to be able to remove the radiator fan. This is not shown since I don't have an automatic. You need special tools for this section.
4. Loosen Water Pump pulley bolts before removing engine belts. (4) 10mm bolts. (Figure G)
5. Removing belts from the engine. Label belts with a marker to indicate the front. If you are reusing your belts, you want to install it going the same direction as before. Draw a diagram of the belt routes. This will help you when you put the belts back on. (Figure H) Remove caps from the belt tensioner pulleys. (Figure I) Use T-50 socket to relieve tension on A/C belt. Use 8mm Allen socket to relieve tension on the water pump / alternator / power steering pump belt. (Figure J)
6. Remove Water Pump Pulley. Remove the (4) 10mm bolts. Picture shows water pump pulley removed (Figure K) NOTE: Thermostat is missing from pictures. I was replacing both at the same time.
7. Remove Water Pump. Remove the (4) 10mm nuts. (Figure K) The water pump has 2 threaded bolt holes to extract the water pump. Use (2) M6 bolts (same bolts used to mount thermostat) to extract water pump. (Figure L) (Tightening torque specifications: Pulley bolts: 10Nm, Water Pump nuts: 10Nm)
8. Reconnect everything in reverse order
9. Refill coolant and bleed system.
a. Open bleed screw and remove cap from expansion tank (Figure O)
b. Turn on car to position B. (engine is off, but cabin fan turns on).
c. Set cabin temperature to highest temp. Set cabin fan to low.
d. Slowly refill coolant until coolant starts to spill out from bleed screw. Your cooling system shouild be air free.
e. Close bleed screw and the put cap back on the expansion tank
f. Turn on engine and make sure there are no coolant leaks. After the engine has cooled, re-check coolant level. Do not open expansion tank cap when engine is hot.