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Pelican Technical Article:

Water Pump Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$200

Talent:

****

Tools:

Set of sockets, wrenches, screwdrivers, two M6 bolts, eye protection

Applicable Models:

BMW 323Ci Coupe/Conv (1999-00)
BMW 323i Sedan/Wagon (1999-00)
BMW 325Ci Coupe/Conv (2001-06)
BMW 325i/xi Sedan/Wagon (2001-06)
BMW 328Ci Coupe (1999-00)
BMW 328i Sedan (1999-00)
BMW 330Ci Coupe/Conv (2001-06)
BMW 330i/xi Sedan (2001-06)

Parts Required:

Water pump, hoses, engine coolant

Hot Tip:

Work with a cool engine

Performance Gain:

Car will cool down again

Complementary Modification:

Change serpentine belt, radiator hoses

BMW E46 cooling system components include:

  • Radiator and coolant overflow tank
  • Belt driven water pump bolted to the front of the engine block
  • Electric cooling fan attached to rear of radiator - the cooling fan is controlled by the engine control module (ECM) via an output final stage
  • Automatic transmission models: Belt driven fan attached to front of water pump, viscous clutch controls fan speed based on engine temperature and rpms
  • Electrically heated thermostat
  • Automatic transmission cooler (heat exchanger)
  • Heater valve and heater core (for climate control)
  • Coolant level sensor inside expansion tank
  • Coolant temperature sensor at cylinder head
  • Radiator outlet temperature sensor
  • Coolant hose and lines

When a water pump begins to fail, you'll notice that the car tends to overheat at a low engine speed or at idle. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a faulty water pump, but it's a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running if you suspect your E46 water pump to be failing. You should feel pressure build up on the back of the hose and surge once you release pressure off the hose. If you feel no pressure, it's a fair bet that the water pump is failing and it needs to be changed as soon as possible. 

In some instances you may also see a slight drip coming from the water pump housing itself. These weep holes are cast into the pump housing and allow excess coolant to drain out if it has leaked past the various seals in the pump. The bearing can fail creating a grinding noise or creating free-play in the shaft also resulting in a coolant leak.

In this article, I'll go over the steps involved with replacing the water pump on the BMW M52 and M54 engine. Be sure to work with a cool engine and confirm the cooling system lacks pressure before opening the cooling system to prevent injures. I also highly recommend you wear eye protection as well.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches. 

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability. 

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

First step is you need to drain the cooling system. See our Pelican Parts Technical Article on Flushing Your Coolant.

Next you will need to remove the cooling fan shroud. See our Pelican Parts Technical Article on Replacing Your Radiator Fan.

If you are looking for more Technical Articles to diagnose or repair cooling issues please visit our E46 page.

Before removing your engine drive belt, loosen four 10mm water pump pulley fasteners but do not remove them completely (green arrows).
Figure 1

Before removing your engine drive belt, loosen four 10mm water pump pulley fasteners but do not remove them completely (green arrows). Remove the engine drive belt but make sure you do not remove the water pump pulley fasteners just yet. See our Pelican Parts Technical Article on Replacing Your Drive Belt.

Remove four 10mm water pump pulley fasteners (green arrows).
Figure 2

Remove four 10mm water pump pulley fasteners (green arrows).

Next, remove the water pump pulley from the water pump.
Figure 3

Next, remove the water pump pulley from the water pump. While the pulley is off, inspect for small cracks or damages. The pulleys can fail unexpectedly, although not that often.

Remove four 10mm water pump pulley fasteners (green arrows).
Figure 4

Remove four 10mm water pump pulley fasteners (green arrows).

The BMW E46 water pump sits deep in the timing cover and it can be tough to get the sealing o-ring to pass through.
Figure 5

The BMW E46 water pump sits deep in the timing cover and it can be tough to get the sealing o-ring to pass through. There are two threaded holes you can install M6 bolts in to extract the water pump.

To remove your water pump from the timing cover, thread two M6 bolts into the sides of water pump.
Figure 6

To remove your water pump from the timing cover, thread two M6 bolts into the sides of water pump.

Use a ratchet to evenly tighten, do a few turns per side, then switch and tighten opposite side, repeat until the water pump o-ring has cleared the timing cover.
Figure 7

Use a ratchet to evenly tighten, do a few turns per side, then switch and tighten opposite side, repeat until the water pump o-ring has cleared the timing cover.

Once your water pump o-ring has cleared the timing cover, you can remove it by hand.
Figure 8

Once your water pump o-ring has cleared the timing cover, you can remove it by hand.

Before installing your new water pump, thoroughly clean the water pump mounting surface and check for debris inside the water pump cavity (inside timing cover). Lubricate the water pump o-ring with coolant and install in the timing cover. Next, hand tighten the four 10mm water pump mounting nuts. Torque four 10mm water pump mounting nuts in a criss-cross pattern to specs. Install the water pump pulley and torque the four 10mm water pump pulley fasteners in a cross pattern. Lastly, install the engine drive belt and the cooling fan shroud in the reverse order of removal. Fill and bleed the cooling system. Once complete, check the cooling system for leaks and, if needed, top up the cooling system.

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Comments and Suggestions:
Rick Comments: I may have over filled the coolant as the level stick was broken or got coolant on main belt. Nonetheless, the belt came off wrapped around fan and sheared it off the pump. Need parts for replacement on a shoestring budget. Aside from pump & o-ring, expansion tank, and assuming the fan and clutch are still okay, what else do I need?
November 7, 2016
  Followup from the Pelican Staff: Pulley most likely or the water pump. COolant alone should not cause the belt to come off, something has to be faulty. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Gels Comments: Do you sell the 4 bolts that hold the water pump pulley to the water pump?
November 1, 2016
  Followup from the Pelican Staff: Yes.Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Eric Comments: This may be a stupid question, but if my front wheels are sitting on 9 inch ramps, will I be able to remove the water pump without draining out the coolant from the radiator or block? I kind of figure gravity will push coolant away from the cavity.
January 2, 2016
  Followup from the Pelican Staff: No, the system has no air, so no matter the angle, there is coolant everywhere. - Nick at Pelican Parts  
shedo Comments: can u please tell me how to chenger from 318 e46 2000 model
August 25, 2015
  Followup from the Pelican Staff: We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799.

However, this article is close: http://www.pelicanparts.com/BMW/techarticles/BMW-Z3/30-WATER-Water_Pump_Replacement/30-WATER-Water_Pump_Replacement.htm

- Nick at Pelican Parts
 
jonny Comments: wen i change my water pump on my 320i will it be a straght fit back on ??
July 23, 2015
  Followup from the Pelican Staff: We don't have 320s here in the US, so I can;t offer advice on the repair. However, if you remove it, installing it would be reverse steps. - Nick at Pelican Parts  
alexburn2003 Comments: I have a top radiator hose that is rock rock solid and the engine temperature is perfect with no increase. The expansion tank recently blew also. could this maybe be a broken water pump blocking something?
November 18, 2014
  Followup from the Pelican Staff: Cooling systems do have pressure in them. If it were too high, the radiator cap would open to relive it. If the vehicle is running normal and not overheating, I would think it is normal. - Nick at Pelican Parts  
TY Comments: What's the thread on the 6MM bolts [1.0 2.0} also how long do they need to be?
September 16, 2014
  Followup from the Pelican Staff: 6x1x50mm should do it. - Nick at Pelican Parts  
Mike Comments: What is the best way to clean to water pump mounting surface? Is there a gasket or is some type of sealant used?
Thanks
December 2, 2013
  Followup from the Pelican Staff: Depends on the model of your car. As for cleaning the old gasket, use a sharp razor blade and work carefully to remove old adhesive and / or gasket. - Nick at Pelican Parts  
Twin Comments: How can I remove the fan nut without buying this special tool ?
November 30, 2013
  Followup from the Pelican Staff: Assuming that you mean the thin 32 mm special fan wrench: The space between the fan and the coolant pump is very tight. It is quite difficult to get any other sort of jerry-rigged tool in there. You'll have to bite the bullet and buy the tool, or pay someone to do the work for you. - Nick at Pelican Parts  

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Page last updated: Wed 12/7/2016 02:20:09 AM