BMW E46 Radiator Repair – 1998-2006 3 Series – All Models

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BMW E46 Radiator Repair – 2-3 Hours

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The Repair Difficulty Level displays graphically how challenging the repair is, from easy to advanced. Easy repairs usually require very few tools, have short repair times and do not require jacking and supporting the vehicle. As the difficulty level rises, expect the repair to demand more time, specialized tools, and better understanding of mechanics to complete the job.

The BMW Repair Guide used this 2003 325ci for the following article. To see other repairs on our site using this actual car, please click on the image below!

Repair Summary
The following article provides detailed instructions on replacing the radiator in a BMW E46 3 series car. Even though we have used a 2003 BMW 325ci to perform this installation, this article can be applied to any E46 3 series vehicle, including the 323i, 328i and 330i coupe, sedan and convertible.

The BMW E46 radiator is a common source of engine coolant leaks, especially in its side plastic tanks.

As the old Benjamin Franklin saying goes, “…in this world, nothing is certain except death and taxes”. If you are a BMW E46 owner, you would probably agree with one more certainty that could added to that proverb; a leaking radiator. It’s not a matter of “if” your BMW E46 radiator is going to leak…it is a matter of “when”. And hopefully that “when” is safely in your garage and not on a long road trip far from home.

The BMW E46 radiator is a simple heat exchanger; hot engine coolant flows into the aluminum core of the radiator and is cooled by outside air being blown across it. This transfer of heat is accomplished by cooling fins that are attached to an internal network of tubing.

Like the rest of the parts that comprise the vehicle’s engine cooling system, the radiator is under constant strain from heat and pressure. The BMW E46 radiator is actually constructed of two plastic coolant tanks joined to an aluminum core. As the plastic ages it can form stress cracks, especially around the coolant hose fittings. The connections between the aluminum and plastic are also common sources of coolant leakage.

An older BMW E46 radiator can also start to deteriorate from within. Corrosion, dirt and debris can build up inside the internal tubing lessening the radiator’s ability to cool the engine. Deposits from high mineral content water can impede fluid circulation inside the core, causing devastating damage to the radiator. Internal mineral deposits in your radiator can be avoided by only using distilled water when mixing your engine coolant.

Replacing the radiator in a BMW E46 3 series is a straightforward procedure for the average home mechanic. It is very important to only use Genuine BMW Antifreeze/Coolant mixed 50/50 with distilled water when refilling your system at the end of this repair.

Parts, Tools and Supplies
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Parts

1. Radiator (required) There are two styles of radiators for the BMW E46, depending on whether the car has an automatic or manual transmission. If your E46 has a manual transmission, please also note that there is a different radiator for all cars produced after 05/2005. You can find the production date of your vehicle in the driver’s side door jamb.

Part Quantity Part # Description
Radiator – 71519 1 17119071519 Genuine BMW – all E46 models except M3 – For vehicles with automatic transmission only
Radiator – 71519MB 1 17119071519 OEM Mahle/Behr – all E46 models except M3 – For vehicles with automatic transmission only
Radiator – 71518 1 17119071518 Genuine BMW – all E46 models except M3 – For vehicles with manual transmission only and production date up to 05/2005
Radiator – 71518MB 1 17119071518 OEM Mahle/Behr – all E46 models except M3 – For vehicles with manual transmission only and production date up to 05/2005
Radiator – 71517 1 17119071517 Genuine BMW – all E46 models except M3 – For vehicles with manual transmission only and production date from 05/2005
Radiator – 71517MB 1 17119071517 OEM Mahle/Behr – all E46 models except M3 – For vehicles with manual transmission only and production date from 05/2005

 

2. Engine coolant (required) – Since you will have to drain the radiator to replace it, you will need to refill your engine with fresh coolant. Only use Genuine BMW Antifreeze/Coolant mixed 50/50 with distilled water in your car. We suggest purchasing two gallons…one gallon pushes the threshold of what you will be draining out of the system during this repair.

Part Quantity Part # Description
Coolant/Anti-freeze 67704 2 82141467704 100% strength, mix 50/50 with distilled water

 

3. Upper radiator hose (optional) The upper radiator hose runs from the thermostat to the coolant reservoir. It is a common source of leaks and cooling system failures in the BMW E46. Since the upper radiator hose will have to be removed to complete this repair, now is a great time to replace if it is getting old. Choose from one of these excellent manufacturers.

Part Quantity Part # Description
Coolant hose – 10952G 1 17127510952 OEM Gates – Upper radiator. All E46 models (except M3)
Coolant hose – 10952R 1 17127510952 OEM Rein – Upper radiator. All E46 models (except M3)
Coolant hose – 10952 1 17127510952 Genuine BMW – Upper radiator. All E46 models (except M3)

 

4. Lower radiator hose (optional) – The lower radiator hose runs from the thermostat to the bottom of the radiator, and is another source of potential cooling system failure.  Now is an excellent time to replace this hose if it is getting old or worn. We give you several quality options to choose from.

Part Quantity Part # Description
Coolant hose – 36408G 1 11531436408 OEM Gates – Lower radiator. All E46 models (except M3)
Coolant hose – 36408R 1 11531436408 OEM Rein – Lower radiator. All E46 models (except M3)
Coolant hose – 36408 1 11531436408 Genuine BMW – Lower radiator. All E46 models (except M3)

 

Tools and Supplies
Floor jack – low profile
Jack stands or Wheel Ramps
8mm socket wrench
10mm socket wrench
T27 torx bit
Fan clutch removal tool
Metal pick
Screwdriver – flat blade
Trim removal tool kit – plastic
Dawn liquid dish detergent
Grease – multipurpose automotive

Procedure

Section 1 – Draining the radiator and removing the lower radiator hoses
Removing the old radiator from your BMW E46 is a straight forward procedure. Unfortunately the most difficult part of the repair is removing the coolant hoses, especially the lower ones which must be done from under the car. The hoses fit tight on their fittings and often must be pried off. Age and heat complicate things since the internal hose o-rings will get stuck on the plastic radiator fittings.  If you are not planning on replacing your coolant hoses during this repair, care should be taken during the removal process so as not to damage them.

  1. Jack and support the front of the car. Not sure how to jack and support your E46? See our article BMW Jacking and Supporting for Repairs and Maintenance.
  2. If the belly pan (aka – skid plate or lower engine cover) is still installed on your vehicle, remove it using an 8mm nut driver. Belly pans tend to disappear on older BMWs – they take a lot of abuse and are one of those parts that owners just don’t spend money on replacing. The belly pan needs to be removed in order to access the bottom of the radiator.
  3. Remove the cap from the coolant expansion tank. This will allow the system to drain thoroughly. bmw e46 radiator - remove the expansion tank cap
  4. Locate the radiator under the front of the vehicle. The drain plug is located on the left side of the radiator.bmw e46 radiator - locate the radiator under the vehicle
  5. Position a 5 gallon drain pan under the drain plug.Position a 5 gallon drain pan under the drain plug.
  6. Using a large flat blade screwdriver, remove the radiator drain plug. Allow the coolant to completely drain from the radiator. When it is finished, replace the drain plug to keep coolant from spilling on the ground while removing the radiator from the car.bmw e46 radiator - Remove the drain plug and allow the radiator to drain
  7. Moving to the right side of the radiator, use a metal pick or flat blade screwdriver to release the metal clamp that locks the lower right radiator coolant hose to its fitting.bmw e46 radiator - release the locking clip on the lower right radiator hose
  8. Position the 5 gallon pan under the hose. Grasp the hose and pull it loose from the radiator. This hose can often be very stubborn. Try rocking it back and forth while pulling on it until it releases from the fitting. If this doesn’t work, try using a large flat blade screwdriver to gently pry it off of the radiator.bmw e46 radiator - use a large flat blade screwdriver if necessary to pry the hose off of its fitting bmw e46 radiator - remove the lower right radiator hose from its fitting
  9. If your car has an automatic transmission, you will need to remove the transmission fluid cooler from the bottom of the radiator. First, locate the fluid cooler on the left side of the car.bmw e46 radiator - locate the transmission fluid cooler
  10. Release the metal locking clamp that secures the fluid cooler to the radiator. The locking clamp has a plastic pull attached to the top of it. Locate the plastic pull and lift it up to release the clamp. If the plastic pull is being stubborn, you can bypass it by just pushing the clamp up from the bottom of the fitting with your fingernail or a small screwdriver (see image below).bmw e46 radiator - raise the plastic pull to release the locking clampIf the clamp will not raise, use your fingernail of a small screwdriver to push it up from the bottom
  11. Position a drain pan under the transmission cooler. DO NOT put your face under the cooler when removing it…there is quite a bit of coolant left in it. Grasp the transmission cooler with two hands and pull it loose from the radiator.bmw e46 radiator - remove the transmission cooler from the radiator.
  12. Next, release the metal clip on the lower left radiator coolant hose. This coolant hose can be very difficult to remove. Take your time, carefully rocking it back and forth to loosen it.  If you still cannot get it to release from the radiator, try using a large pair of slip joint pliers (see image below) to gently rock it while pulling. Use a large flat blade screwdriver to try and gently pry it off while pulling with the pliers, being careful not to damage any fittings. Remove the hose from the radiator.Use a large pair of pliers if necessary to get the hose fitting off of the radiator.bmw e46 radiator - remove the left lower radiator hose.

 

Section 2 – Removing the fan shroud and cooling fan
The fan shroud and cooling fan must be cleared out to allow enough space to remove and reinstall the radiator. The cooling fan is notoriously difficult to remove on many BMW E46s due to its mounting nut (clutch nut) seizing to the pulley that spins it. We give directions below on how to remove the fan and shroud if you encounter a seized clutch nut during your repair.

  1.  Start by disconnecting the mass air flow (MAF) sensor.BMW E46 radiator- disconnect the mass air flow sensor
  2. Using a flat blade screwdriver, loosen the hose clamp on the intake boot.BMW E46 radiator - loosen the intake boot clamp
  3. Unlatch the four clamps on the lid of the intake muffler. Note that one of the clamps is difficult to get to…use a metal pick to release if you can’t reach it with your fingers. Remove the lid from the vehicle.BMW E46 radiator - unlatch the intake muffler lidRemove the intake muffler lid from the vehicle
  4. Using a 10mm socket wrench, remove the two intake muffler mounting bolts. Remove the intake muffler from the engine compartment.BMW E46 radiator - remove the two intake muffler mounting boltsBMW E46 radiator - remove the intake muffler from the car
  5. Remove the plastic air intake tube.BMW E46 radiator - remove the plastic air intake tube
  6. Use a trim removal tool to remove the three plastics rivets anchoring the air intake to the frame of the vehicle. Remove the intake from the vehicle.BMW E46 radiator - remove the air intake tube
  7. Remove the air quality sensor and the wiring harness connector from the fan shroud and safely tuck out of the way.BMW E46 radiator - remove the air quality sensor Remove the wiring harness from the side of the fan shroud
  8. Release the clamps securing the upper radiator hose to the thermostat housing and the expansion tank. Remove the hose from the engine. BMW E46 radiator- release clip connecting upper radiator hose to thermostat BMW E46 radiator - release clips attaching upper radiator hose to expansion tank Remove the upper radiator hose from vehicle
  9. Don’t try and remove the fan shroud yet…it is easier to remove with the cooling fan and fan clutch. There is also less chance of breaking the fan shroud if you remove it with the cooling fan.
  10. Next, the infamous cooling fan and fan clutch must be removed from the water pump pulley. If the nut on the fan clutch is seized and cannot be removed from the water pump pulley with the special fan clutch removal tool (which is a very common occurrence), then you will have to unbolt and remove the cooling fan from the clutch. Remember the fan clutch nut is a reverse thread…you must turn it clockwise to loosen it.BMW E46 radiator - locate the fan clutch nut
  11. The first step in all of this is to try and remove the fan clutch from the pulley with the special fan clutch removal tool. Place the fan clutch tool on the pulley and the clutch nut as shown in the following image. Remember the fan clutch nut is a reverse thread…you must turn it clockwise to loosen it.Fan clutch removal toolBMW E46 radiator - install the fan clutch tool on the clutch nut and the pulley boltsFan clutch tool on water pump pulley
  12. The nut is a reverse thread…this means you must turn the nut CLOCKWISE to remove it.BMW E46 radiator - remember the fan clutch nut is a reverse thread. Turn it clockwise to loosen.
  13. If you can loosen the nut, then spin the fan clutch nut off of the pulley. If the nut is seized and cannot be removed, then you will need to follow additional steps below to remove the cooling fan blades. Either way, proceed to the next step #14.
  14. Remove the right T27 torx radiator anchor screw. This screw also anchors the fan shroud to the radiator. The left side of the fan shroud is anchored to the radiator with a plastic rivet. Remove the rivet with a trim removal tool. BMW E46 radiator - remove the fan shroud anchor fasteners BMW E46 radiator - remove the fan shroud anchor fasteners
  15. If you were able to remove the fan clutch from the water pump pulley, grasp the shroud and the cooling fan and slowly remove them from the engine compartment together and proceed to Section 3 below. If the nut was seized and you could not remove the fan, proceed to the next step #16.
  16. If the clutch nut is frozen and you could not loosen it, slowly pull the shroud up and out of the front of the vehicle around the cooling fan. Don’t pull on it if it gets hung up…you may have to get under the front of the car to help guide it behind the fan blades. Take your time and do your best to get it out with minimal damage to the shroud.Remove the fan shroud from the engine if the clutch nut is frozen.
  17. Use a T30 torx bit to remove the three fan clutch mounting bolts. Remove the cooling fan from the vehicle.BMW E46 radiator - remove the fan clutch torx bolts BMW E46 radiator - remove the fan clutch torx boltsRemove the cooling fan from the vehicle

 

Section 3 – Removing the BMW E46 radiator from the vehicle

  1. Locate the lower coolant hose attached to the rear of the expansion tank. Use a metal pick to release the locking clip on the end of the hose. Pull the hose loose from the expansion tank.bmw e46 radiator - locate lower coolant hosebmw e46 radiator - remove lower coolant hose and let drain
  2. Remove the coolant expansion tank by releasing the locking clamp on the bottom of the tank. The locking clamp is located on the bottom right side of the tank. To release the clamp, simply reach your hand down and slide it out.bmw e46 radiator - release the expansion tank locking clamp bmw e46 radiator - expansion tank locking clamp
  3. Grab the top of the expansion tank with two hands and attempt to pull it free from the radiator. You may have to gently rock it back and forth to get it to release. Older tanks may be particularly stubborn and require a couple of small taps with a screwdriver on the bottom to get them to release.bmw e46 radiator - pull the expansion tank free from the radiator
  4. When the expansion tank is loose, flip it over and disconnect the level sensor.
  5. Use a T27 torx bit to remove the left radiator mounting screw.bmw e46 radiator - Remove the left radiator mounting screw
  6. The radiator can now be removed. Tilt the radiator back, then pull it up and out of the engine compartment.bmw e46 radiator - Tilt the radiator backward to remove bmw e46 radiator - remove the old radiator from the car
  7. Lay the old radiator down on a work bench.
  8. If you are going to reuse the old expansion tank mounting plate, remove the two T27 torx screws anchoring it to the radiator. Use a large flat blade screwdriver to gently pry it off of the radiator fitting. Remove the mounting plate from the radiator.bmw e46 radiator - remove the screws anchoring the expansion tank mounting platebmw e46 radiator - remove the screws anchoring the expansion tank mounting platebmw e46 radiator - pry the expansion tank mounting plate off of the radiatorRemove the expansion tank mounting plate from the old radiator

 

Section 4 – Installing the new BMW E46 radiator
Installing the new radiator is very straightforward – it is basically following the above instructions in reverse. One problem many mechanics run into is reinstalling the coolant hoses. If you are having issues reinstalling the coolant hoses and getting them to lock into position, apply some liquid dish detergent to the fittings. This will help the hoses slide on without any issues. NEVER use a petroleum based oil or grease on the hose o-rings. This can cause leaks.

  1. Unpack the new radiator and lay it on the work bench. Double check to make sure you have the correct part number.bmw e46 radiator - unpack the new radiator and double check the part number
  2. Some radiators (like ours below) come with the new drain plug already installed. If your radiator was shipped without the drain plug installed…install it now.bmw e46 radiator - If the drain plug is not already installed, install it now.
  3. Install the expansion tank mounting plate on the new radiator, applying pressure with the palm of your hand to insure a tight connection. Reinstall the two torx screws.
  4. Install the new radiator into the car. Reinstall the left and right T27 mounting screws to hold the radiator in place.bmw e46 radiator - Install the new radiator.
  5. Visually locate the two fittings on the expansion tank mounting plate that the tank connects to.bmw e46 radiator - expansion tank fittings
  6. Slowly lower the new expansion tank onto the mounting plate fittings. Note that the tab on the back of the tank should fit into the groove on the radiator.Make sure to guide the tab on the back of the tank into the groove in radiator.
  7. When you are confident the tank is positioned correctly, use the palm of your hand to push the expansion tank firmly onto the expansion tank plate. Reach down the right side of the tank and push the locking clip in.bmw e46 coolant radiator - use the palm of your hand to set the tank in place
  8. Reinstall the lower coolant hose back onto the expansion tank. Always close the locking clamps BEFORE installing the coolant hoses on their fittings. You want to hear them “snap” into place when installed.bmw e46 radiator - reinstall lower coolant hose on the back of the expansion tank
  9. If you had to remove your cooling fan from the clutch because of a seized nut, reinstall it using the three torx mounting bolts. Make sure you have the fan blades facing the correct direction. Torque the mounting bolts to 10 Nm (7.5 ft-lb).Reinstall the cooling fan if the clutch nut was seized.
  10. If you were able to remove your cooling fan using the fan clutch tool, liberally apply some multipurpose automotive grease to the clutch nut threads. This will prevent it from seizing up in the future and make it easy to remove for future repairs.bmw e46 radiator - add some grease to the fan clutch nut threads
  11. Lower the fan shroud and the cooling fan together into the front of the vehicle. Spin the cooling fan onto the water pump counterclockwise to tighten. Use the special fan clutch tool to tighten the nut as snug as you can get it. Since it is a reverse thread, it is self tightening so you do not have to worry about torquing it.bmw e46 radiator - Lower the fan and the shroud together into the front of the engine. Spin the fan onto the water pump counterclockwise and tighten.
  12. Remove the right radiator mounting screw (it was installed earlier to hold the radiator in position). Move the fan shroud into its correct position then reinstall the screw so it anchors the shroud and the radiator to the frame. Reinstall the plastic shroud rivet.bmw e46 radiator - reinstall the right radiator mounting screwbmw e46 radiator - install the left shroud rivet
  13. Reinstall the upper radiator hose that runs from the thermostat to the expansion tank. Use the palm of your hand to put pressure on the hose so it properly clicks into place on the expansion tank. If the hose is being obstinate and won’t click onto the fittings, use some liquid dish detergent to lubricate the connection. Once again…always close the metal clamp before installing a coolant hose on its fitting(s). We cannot stress this enough. It is very important to hear the “click” when reinstalling coolant hoses.bmw e46 radiator - install the upper radiator hose.
  14. Move under the vehicle and reconnect lower left radiator coolant hose. The lower left hose can often be more difficult to install than it was to remove. If you can’t get it to snap on its fitting, try applying a little liquid dish detergent to the o-ring to help it slide onto the fitting. NEVER USE a petroleum based lubricant like grease or oil to lubricate the o-ring.bmw e46 radiator - use some liquid dish detergent to lubricate stubborn hose fittings.bmw e46 radiator - Apply liquid dish detergent to o-ring to help hose slide onto fitting
  15. Inspect the transmission cooler – make sure the two o-rings are intact on the inlet ports. Reinstall the transmission cooler. Use the palm of your hand to apply pressure to make sure the cooler o-rings seat properly in the radiator. Close the metal clamp by lowering the plastic pull.bmw e46 radiator - Inspect the o-rings on the transmission cooler.bmw e46 radiator - Install the transmission cooler back into the radiator
  16. Reinstall the lower right radiator hose. Once again, this hose can be as difficult to install as it was to remove. Use dish detergent to lubricate the o-ring so it slides on.
  17. Double and triple check all of the hose connections to make sure you didn’t over look anything. Also check to make sure the drain plug is snugly installed. If everything looks secure, proceed to the next section.
  18. Reinstall the air quality sensor and the wiring harness connector into the fan shroud.
  19. Reinstall the intake tube, intake muffler and reconnect the MAF sensor.

 

Section 5 – Refilling the BMW E46 radiator with coolant, bleeding and testing
Refilling and bleeding the coolant system in your BMW E46 3 series car is a very simple procedure. The goal is to remove any air bubbles trapped in the coolant line that could potentially cause the engine to overheat. Unlike many other repair articles, the BMW Repair Guide uses the “double bleed” approach on their BMW E46 3 series cars. This is a proven method that we have used for years with 100% success. The double bleed method entails purging the air out of the coolant system twice; once with the engine off, and then again with the engine running. We have found this to be the most complete method of removing all of the air out of the E46 cooling system.

  1. Only use Genuine BMW Antifreeze/Coolant mixed 50/50 with distilled water in your vehicle. Using any other brand of antifreeze/coolant in your BMW is strongly discouraged. Genuine BMW Antifreeze/Coolant was specifically engineered for your BMW…other brands may not cool your engine correctly.Only use Genuine BMW coolant.Only use distilled water to mix with coolant
  2. Loosen the bleed screw on the upper coolant hose.bmw e46 coolant expansion tank - loosen the bleeder screw
  3. Turn the ignition on. Do not start the vehicle.Turn ignition on but do not start car
  4. Set the HVAC temperature controls to full warm and the fan speed to its lowest setting (this opens the heater core and activates the secondary electric coolant pump).
  5. Slowly fill the expansion tank with coolant until it starts to spill from the bleeder screw.bmw e46 coolant expansion tank - fill the expansion tankbmw e46 coolant expansion tank - fill system until it flows out of bleeder screw
  6. When the coolant spilling from the bleed screw is free of air bubbles (just a steady stream of coolant), tighten the screw and replace the expansion tank cap.Replace the tank cap
  7. Start the engine.
  8. With the engine running, loosen the bleeder screw again. You should get more air bubbles coming out until there is a steady stream of coolant being pushed out of the bleeder hole. Tighten the bleeder screw.
  9. Allow engine to reach operating temperature (about 5 minutes if cold). Keep an eye on the engine temperature gauge…the needle should stay right in the middle. Check all of the hoses for leaks.bmw e46 coolant expansion tank - watch the temperature gauge when engine is running.
  10. Allow the engine to cool down. Recheck the coolant level in the expansion tank and top off if necessary.

BMW E46 Radiator Replacement Finished
If you have any questions or comments, please feel free to contact us. And congratulations for Doing It Yourself!

The Repair Difficulty Level displays graphically how challenging the repair is, from easy to advanced. Easy repairs usually require very few tools, have short repair times and do not require jacking and supporting the vehicle. As the difficulty level rises, expect the repair to demand more time, specialized tools, and better understanding of mechanics to complete the job.

 

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