Water Pump
Contents |
Overview
In this section we will cover inspection of water pump and basic replacement procedure. Please keep in mind that a failed water pump bearing might seize and cause thousands dollars of damage.
Inspection
- Inspect water pump for visible leaks at gasket and thermostat level.
- If thermostat fails to open the hose leading to water pump from radiator (passenger side) will get extremely hot.
- Watch fan clutch for any wobble, take off the belt and examine the pulley. It should be moving with resistance and never 'spin', have no back and forth play of any sort.
Video Walkthrough
Parts Required
- New water pump with metal impeller (comes with gasket and 2 pipe o-rings)
- 2 gallons of BMW coolant and 2 gallons of distilled water
- Silicon gasket maker for water pump
- Locktite
Optional Parts
While doing this job you can also replace following:
- Fan clutch (highly recommended)
- Upper and lower radiator hoses (highly recommended)
- V-Belt / A/C belt
- Both tensioners
- Idler / Adjusting / Water pump / Power steering pulleys
Tools Required
- Drain pan
- 10mm / 12mm / 13mm and 17mm sockets
- Two ratchets with short and longer extension
- Rubber mallet
- 32 MM thin wrench
- Torque wrench
- Screw driver
Replacement
- Jack up the car
- Make sure the car is cold, place drain pan under driver side of radiator and remove drain plug (located on bottom, driver side of radiator)
- Put 32MM thin wrench on fan clutch bolt (connected to water pump), hold the water pump pulley with your hand and apply counter-clock pressure (
fan clutch is reverse threaded) on the wrench until bolt becomes loose. If it's too rusted you might need a special BMW pulley holder. Try giving it a wack or two with rubber mallet. Once you get it off, spin the fan (counter-clock) until it comes off (catch it before it hits the ground).
- Relief tension from V-Belt (http://www.e34addicts.com/V-Belt_Replacement) and take out the belt
- Jack the car down, remove upper radiator hose and smaller pressure hose (driver side) from top of the radiator (and from water pump)
- Remove lower radiator hose from radiator and water pump
- Unplug sensor from passenger side of radiator
- Push radiator down and release two clips securing it from both side (top right and left)
- Take out radiator and safely place it on a side
- Using rachet with small extension take off 13mm x 8 bolts from harmonic balancer, it's better to connect bigger rachet to each bolt and tap it loose with mallet
then use smaller rachet to quickly take them off.
- Give a slight tap to harmonic balancer with rubber mallet and take it off (pull it forward)
- Remove all 10mm bolts from water pump, there will be 2 longer bolts on top left of water pump located on opposite of each other. Note the location of them.
- Tap water pump slightly with mallet while holding it, then pull it forward while holding two pipes that connect to it in the back (preventing them from unplugging
from the rear).
- Remove water pump, take razor and scrape everything off the block. Carb clean it and dry everything
- If you are also replacing thermostat, go put it on the new water pump (use locktite). Use silicon water pump gasket where thermostat makes contact with water pump.
- Transfer (or use new) water pump pulley on your new water pump.
- Apply silicon water pump gasket around gasket mating surface (on water pump it self), go around the bolt holes/etc. Also put some on top of the two pipes sticking out of the engine
- Put your new water pump gasket on top of silicon you applied on water pump and press it on it until it sticks
- Now the fun part, you have to put the new water pump in straight and align the bolts perfectly while aligning the pipes in without moving the gasket you just attached. This might take few
attempts. The trick is to have two longer bolts near by and alot of light. Put the bigger pipe in the water pump slightly, followed by navigating it into a smaller pipe. Look at the bolt holes and slowly allign it. Once you are ready press in the water pump until you feel that both of the pipes went inside the rubber o-rings in the water pump. Quickly take two longer bolts and put them in and inspect both sides of water pump for proper alignment (make sure gasket is not sticking out of anywhere). Repeat until you get this right.
- Everything else is reverse of removal. Use locktite on water pump and harmonic balancer bolts)
Bleeding
Our cars are self bleeding but you still need to follow few steps. Fill up the coolant until the expansion tank is full, take off small line running to top left (driver side) to the radiator (right above upper radiator hose). The coolant level should go down and bubble. Fill it up again (you might hear hissing and coolant will come out from the smaller nipple), keep filling it until it stops. Then (do not put on the expansion cap on) start the car and let it run for 5 minutes. Tighten the small line up and continue to let the car run until the temp needle hits the center. Squeeze both upper and lower radiator hoses to remove trapped air then close the expansion tank and observe temperature for another 10 minutes.
Torque Specs
- Pulley to coolant pump: 10 nm
- Vibration damper to crankshaft: 22 nm
- Thermostate housing to coolant pump: 10 nm
- Coolant pump to timing chain cover 10 nm
