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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 02-10-2012, 03:51 PM   #1
bimmerfan08
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DIY: E46 M3 detailed water pump replacement, thermostat replacement, & coolant flush

So first things first, I would like to thank members of previous threads for making cooling and cooling part DIYs in the past. However, most of them were complete but were missing a few parts of the process or detailed steps. That led me to have to search through other DIYs and so during my repair of the cooling system, I had several DIYs open (5 to be exact) discussing the water pump and thermostat repair, as well as the complete coolant flush. Here Ive layed out the process from start to finish with lots of pictures, descriptions, and numerical values. Thanks for viewing and again, thanks to the forum for being a guide for my own DIY.

Tools needed:
3/8" drive ratchet
8mm hex socket
10mm hex socket
13mm hex socket
16mm hex socket
T25 torx bit drive socket
8mm hex bit drive socket
3/8" ratchet extensions
32mm fan clutch wrench
BMW or similar fan clutch tool
3/8" drive torque wrench
Needle nose pliers
Phillips head screwdriver
Straight head screwdriver (the shorter, the better)

Parts and supplies needed:
1 Thermostat (PN: 11531318274)
1 Water pump (PN: 11517838159)
1 Water pump steel gasket (PN: 11517831099)
1 Thermostat O-ring, these are 64.77x2.62mm (PN: 11531318402)
2 Water pump O-rings, these are 8x13mm (PN: 11537830712)
1 Water pipe O-ring, these are 38x3mm (PN: 11537830709)
1-2 Gallons BMW OEM antifreeze coolant (PN: 82141467704)
1 Gallon distilled water, can be found at any grocery store
1 large container to catch coolant
Rags and paper towels to clean up coolant spillage
Small plastic bags to contain screws and bolts
E46 3 series Bentley manual for reference if you have it

Also now is a good time to order any parts that require the fan and fan area to be disassembled. Parts such as pullies, fan clutch, fan, belts, sensors, radiator, coolant hoses, alternator, and air filter. There are other DIYs for these parts on this forum.


Step 1: Allow the cooling system to cool before attempting to remove the hot coolant if the car has been running. This will also allow the engine bay to dissipate any heat built up during operation of the car.

Step 2: Pull car into garage and pop open hood. This will also allow the engine bay to cool faster if it isnt already fully cooled.



Step 3: Gather all tools necessary for the task. Above is the list of tools needed for this job.



Step 4: Jack up car enough with enough space to remove underbody splash guard and insert a large bin to catch coolant. I used the center support jack pad in the front of the car, but depending on height conditions you may need to slip a piece of wood under the wheels to reach the CSJP. Make sure your jack is in working condition and functional.



Step 5: While car is jacked up, place jack stands underneath the two side jack points along the body side closest to front of car. They are rectangular in shape and a durable plastic compound. Make sure jack stands are centered correctly underneath them. Lower jack slowy to transfer load of vehicle onto the jack stands.



Step 6: Remove jack front of car and reposition to either side of car to jack up just enough to touch the center support jack pad. This is a more of a safety measure but I like to think safe rather than sorry. I placed the jack right behind the driver front wheel well and was able to jack up from that location.

Step 7: Remove the 7 screws holding the underbody splash guard from underneath the car. They are 8mm hex. There will be 4 screws on the sides of the splash guard and 3 to the rear of the splash guard. When all screws are removed, slide toward the rear of the car and down.



Step 8: Position your container for catching coolant underneath the engine bay. I used a rubbermaid plastic drawer from a plastic cabinet that was about 22" long by 14" wide and about 8" high.



Notice the jack in the background providing safety support.



Step 9: Working from top of engine bay, remove the intake duct by locating the 4 plastic expansion rivets. Here I used needle nose pliers to pull up on the center pins. Place the 4 rivets in a plastic bag. Ive marked them in red to show their location.



The air intake duct removed.





Step 10: Remove the air intake duct elbow that slides into the front of the air filter box. It simply lifts up and out.



Step 11: Unplug MAF sensor connection. It is located just behind the air filter box on the air duct. Simply push the clips in and pull out.



Step 12: Release the 2 metal air box clips near the bottom of the air box.



Step 13: Loosen clamp around the air duct leading into the air box by inserting straight head screwdriver. There are 2 clamps on this air duct. 1 is located around the air box entrance itself and the other clamp is located right behind the MAF sensor location. You can loosen either but I chose the air box clamp. Once the clamp has been loosened, simply pull the air duct off and lift the entire air filter box assembly up and out of the car. I have circled the 2 clamps in red.



Space left after air filter box top and duct have been removed.



Step 14: Locate the Xenon ballast igniter box and unplug the two sensor wires feeding into the top of it. These are again simply clip and pull up. The one wire has a rubber boot that needs to be pulled back to expose clip. I have marked the locations with red circles.



Step 15: Pull up on the black plastic cover for the Xenon ballast igniter box. It doesnt take much force. Set aside and note location of the 3 retaining bolts.



Step 16: Using a 10mm hex socket, remove the 3 retaining bolts for the Xenon ballast igniter box. You will also need a 3/8" ratchet extension here attached to the ratchet to clear the igniter box while swiveling the ratchet.

Step 17: Once the 10mm bolts have been removed, set the Xenon ballast igniter box to the side somewhere. Be careful not to over extend the length the wires can travel. Now simply pull up on the lower portion of the air filter box and remove.



The lower air filter box section.



Step 18: Remove the plastic expansion rivet on top of the engine shroud. Again I used needle nosed pliers to pull the center pin up. The rivet is circled in red.



Step 19: Locate the plastic expansion rivet for the left (if youre facing engine bay) engine shroud piece. It is directly in front of the upper timing chain area. Ive circled the rivet in red.



Step 20: With plastic expansion rivet removed, pull up and out on the left engine shroud piece. It doesnt take much effort, so go easy.



The engine bay after the left engine shroud has been removed.



Remember to bag all screws, bolts, and rivets so they that dont get separated.



Step 21: Working from the right side of the engine (again, if facing it) locate the plastic expansion rivet for the right side engine shroud. It is right beneath the upper radiator coolant hose that comes off the radiator. Leave this engine shrould loose for now as the hose has to be disconnected to remove it completely.

Step 22: While on the right side of the engine, locate and remove the upper fan shroud retaining bolt. It uses a T25 torx driver bit socket. Ive circled the location in red. Also notice the right engine shroud piece hanging loosely on the upper radiator hose in the background. This is okay.



Step 23: Locate and remove the lower fan shroud retaining bolt on the right side of the engine. It is directly below the upper retaining bolt. The area gets a little tight but it is still accessible. Ive circled the bolt in red and again this is a T25 torx driver bit socket.



Step 24: Working from the left side of engine if facing it, locate and unclip the sensor connection on top of the radiator. Like all BMW sensors, it simply unclips and pulls out. Tuck away to the left side near the secondary air pump area. Ive circled the clip in red.



Step 25: While looking at top of radiator, locate the upper fan shroudl retaining bolt for the left side if facing the engine. This bolt should be a few inches down and to the left of the sensor connection that was unclipped in step 24. The head is again a T25 torx driver bit socket. Ive circled the location in red.



Step 26: Unclip the connection that sits in the left fan shroud support. It is gray in color and has large clips. Remove top portion of connection and set aside to the left. Remove the lower portion by pulling up and to then towards the engine. Set this portion to the left side as well near the secondary air pump.



Step 27: Locate and remove the last fan shroud retaining bolt. It it is easier to remove this bolt from under the car. It is directly below the lower radiator hose. Again, the head uses a T25 torx bit drive socket. Ive circled the location in red.



Remember to bag those retaining bolts!



Step 28: Here comes the tricky part. Place your 32mm wrench around the fan nut. Next, place the fan tool around 2 of the bolt heads on the water pump pulley. The water pump pulley bolts are in a rectangular pattern, not square, so you may need to adjust the end of the fan tool youre using. The fan nut is reverse threaded, so to loosen it, you need to twist to the right. With the fan tool in your left hand and the 32mm wrench in your right hand, pull in opposite directions, i.e. outward. Make sure the 32mm wrench is being pulled to your right. It will take some force, but the fan nut should come lose. I used a screwdriver here to lodge the water pump pulley but I recommend the fan tool to make the job much easier. The fan nut is circled in red.

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"In any system with finite resources and infinite expansion of population—like your business, or like all of humanity—innovation is essential for not only success but also survival. The innovators are our leaders. You cannot separate the two. Whether it is by thought, technology or organization, innovation is our only hope to solve our challenges."

Last edited by bimmerfan08; 02-10-2012 at 04:02 PM.
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Old 02-10-2012, 03:51 PM   #2
bimmerfan08
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Step 29: Remove the fan and fan shroud by pulling up and out. The shroud needs to be completely loose for this step, so make sure it is pulled up first. Unthread the remainder of the fan nut if you havent already done so. Be careful to not let the fan fall off the end of the water pump threads. Hold fan in one hand and spin to the right with the other. Pull fan up with the fan shroud together. You may be able to wedge the fan out first once half of the fan shroud is above the engine. Again be careful here. Set the fan and fan shroud aside in a location where they wont get damaged. The oil cooler can be relocated on the bottom and moved so that the fan can be taken out from the bottom but I chose to remove it from the top.



You now have the clear working space you need to continue on with this fix.



Step 30: This is the easier method in draining the coolant that doesnt require removing the lower radiator hose. Locate and remove the coolant temperature sensor. It is located directly on top of the lower radiator hose. Simply unclip and pull upward and out. Coolant will begin to flow out of the sensor hole. To relieve the pressure in the cooling system and let coolant out, untwist the cap on the coolant expansion tank. Have your container ready to catch the coolant. Ive circled the location in red.



Coolant will begin to flow rapidly out of the sensor hole. If you want, you can place a small funnel over the hole to reduce the coolant spillage.



This is a good time to replace the sensor especially if the green O-ring is deformed.



Step 31: Locate the AC belt. It is on the lower pullies near the bottom of the engine. Below the tensioner pulley is a 16mm head. Using the 16mm hex socket, twist the head to relieve the tension on the AC belt. Remove and mark the direction of the belt rotation if using again. I simply placed a directional arrow on the belt with a Sharpie marker. Ive circled the area in red.



Step 32: Locate the tensioner pulley bolt for the main drive belt. It is in the center of the tensioner pulley. Insert the 8mm hex driver bit socket and twist to remove tension on the belt. Again, mark the roation of the belt with a Sharpie marker. Ive noted the location in red.



Hang belts up and out of the way.



Step 33: Locate and remove the 4 water pump pulley bolts. They have 10mm heads so use a 10mm hex socket to remove them. Remember the water pump pulley is located on the water pump threaded shaft.



Here is my water pump pulley. On the inside was brown burnt coolant that was caking the pulley. I simply cleaned using a rag and some water.



Clean water pump pulley.



Step 34: Locate and remove the thermostat housing retaining bolts. They are to the right side of the black engine cover in front of the throttle position sensor. Unclip the black retaining clip and set aside the black plastic wire housing. The heads are 10mm so use a 10mm hex socket to remove them. There are 3 total.



Bag the bolts to prevent separation. I believe the metal piece that comes off the top of the thermostat housing is one of the engine hoist connection points but I could be wrong.



Step 35: Next, grad a straight head screwdriver and locate the upper radiator hose clamp that connects to the thermostat housing. Untwist this enough so that clamp relieves tension on the rubber hose.



Step 36: Pull upper radiator hose to your right if facing engine. It will take a little force but should slide off. Some coolant may leak here but thats okay.



Step 37: Pull up and towards you on the thermostat housing, be gentle but it should just slide off. I left the lower radiator hose connected to the housing and set it down in the lower part of the engine bay. If need be, simply loosen the clamp around the hose with a straight head screwdriver and pull off the housing to remove it.



Step 38: The thermostat is located in the bottom of the thermostat housing. It simply slides out. This is the old thermostat. It has a brownish hue to it.



Step 39: Now is the time to replace the O-ring on the back water pipe. Remove the old one and replace with the new one (PN: 11537830709). Make sure to use a water-based lubricant on the O-ring such as dish soap.



Step 40: Locate the 5 bolts that hold the water pump in place. The 2 upper bolts are longer than the other 3. The heads are 10mm so use a 10mm hex socket to remove them. Ive noted the locations in red. The 5th bolt is under the water pump, youll have to feel for it but its not hard to remove. Coolant will surely leak out once the water pump is removed. Place the catch container directly below the water pump area.



Step 41: Slowly pull the water pump assembly outward and up. Be careful not to bend the black water pipe that feeds into the left side of the water pump. Throw away old water pump steel gasket. Locate the two smaller black water pipes that connect to the water pump. On the end of these pipes are rubber O-rings. Slide off and replace O-rings with new rings (PN: 11537830712). Lube with small amount of dish soap. Ive circled them in red.



My old water pump. Has a stamp date of 12/01 and was taken off the car at 103,851 miles. Plastic impellars are intact and no signs of cracking. The water pump bearings were no good though as the shaft spun freely with no resistance.



Step 42: Working from underneath the car, locate this metal canister (I believe it has something to do with the VANOS). It is on the left side of the engine block if facing the engine underneath the headers. There is a metal closure around it. Using a 10mm hex socket, remove the bolt and collar that hold the metal closure shut. Once removed, the left side of the closure swings open. Pull the canister out and push up near the headers so that it is out of the way.



Step 43: Locate the coolant plug on the bottom side of the engine block. It should be directly behind the canister just removed. The head is 13mm so use a 13mm hex socket and 3/8" extension on your wrench to reach it. Caution: there will be a lot of coolant that comes out of here so be ready with your catch container.



The coolant plug. There is a metal washer near the head, I flipped this around and reused it.



Step 44: This is your chance to flush the coolant system and block if you want to. I simply used a garden hose to flush it. I inserted the hose into the thermostat housing water pipe to flush the block and into the expansion tank. I also inserted the hose into the upper radiator hose to flush the radiator. After running hard water through the cooling system, it is advised to keep the drainage areas open and flush the system with distilled water to force hard water up and out. In other methods, Ive seen members using the hose on their shop-vac to blow out the remaining water from the flush. There is the chance or introducing outside foreign material using a shop-vac, so if possible, use compressed air to blow water out of the system.



The amount of fluid after a small flush.



The color of the fluid after flush. There were some dark areas in the coolant.



Step 45: At this point you can go on to replace the other cooling system parts such as the radiator, sensors, and hoses. I had to do a quick fix of my water pump, but Ill eventually update this DIY with the other half of the cooling system overhaul. Installation at this point is reverse of removal. Replace the coolant drain plug at bottom of engine block using 13mm hex socket. Torque to 18 ft-lb. Also replace canister into closure and close with the 10mm bolt and collar you removed.

Step 46: Pull new water pump from box and admire the machining and how clean it is. Place the water pump steel gasket (PN: 11517831099)
on the back side of the new water pump (PN: 11517838159). Make sure to align the water pump steel dowels through the steel gasket and that all bolt hole are aligned. There are 2 water pump dowels that protude from the pump itself. Insert a new thermostat O-ring (PN: 11531318402) into the top of the water pump where the circular cutout has been made for it. Lube with small amount of dish soap.

Step 47: Replace water pump back into its location. Make sure that the back water pipes are connected near top of water pump and that it slides in correctly. The water pump dowels should slide into the two dowel holes on the face of the block. Replace the 5 bolts for the water pump and only torque each one to 7 ft-lb. These use a 10mm hex socket.



Step 48: Place the new thermostat into the bottom of the thermostat housing and realign on top of the water pump. This picture shows the orientation the thermostat should be in regards to the water pump.



Step 49: Replace the long threaded 10mm bolts to the top of thermostat housing along with the engine hoist piece. There are 3 bolts total and require only 7 ft-lb torque. Remember to use 10mm hex socket for these bolts. Re-clip the black plastic wire housing removed from earlier.



Step 50: Reconnect the upper radiator hose and lower radiator hose if removed, to the thermostat housing. Remember to slide the right side engine shroud piece back over the upper radiator hose if you removed it.

Step 51: Place the temperature sensor back into its location on the lower radiator hose.



Step 52: Align the water pump pulley onto the new water pump shaft so that the holes sit flush with each other. Remember, the bolt orientation is rectangular, not square, so twist the pulley around until you can feed a bolt through. These require a 10mm hex socket and should only be torqued to 7 lb-ft.



At this point, everything is reverse of removal. Just backtrack through the above steps in order to replace everything. The engine bay should look as it did before the repair process.



Jack up the car and remove the jack stands and let the car sit level on the floor again. Make sure that you have reconnected all the coolant parts and installed everything back to normal. Make a mixture of 50-50 BMW coolant and distilled water. This mixture is for normal temperature ranges. The cooling system calls for 5 liters of BMW coolant and 5 liters of distilled water. I used 4 liters of BMW coolant and about 5 liters of distilled water before the system was full. You may need more or less depending on how much coolant was extracted from the system.

Locate the bleeder screw on the top radiator hose underneath the aid duct intake. Open it up once the coolant system has been topped off using a phillips head screwdriver and allow any air to escape from the radiator. Most of the air in the rest of the system will migrate towards the expansion tank since that is the highest location for the coolant system. Close bleeder screw and turn the car on to make sure the system looks and sounds okay. Go for a short drive to allow the system to circulate the new coolant. Any free air will be forced to the top of the system. Open the bleeder screw to allow anymore air to escape once the coolant has cooled. Then check the coolant level in the expansion tank to make sure the air displacement didnt lower the fluid level drastically. Top off if needed. Drive the car for the next few days and keep an eye on the temperature guage. If the car begins to overheart, shut it off, and check the car for leaks or leaking parts. If all is well, replace the underbody splash guard. Dispose of the old coolant properly since it is highly toxic to animals and children.

Be sure to clean the engine bay and any spilled coolant. You can cover up any electrical components and use a gentle stream of water to hose the engine bay.

Thanks for reading.
__________________
"In any system with finite resources and infinite expansion of population—like your business, or like all of humanity—innovation is essential for not only success but also survival. The innovators are our leaders. You cannot separate the two. Whether it is by thought, technology or organization, innovation is our only hope to solve our challenges."
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Old 02-13-2012, 01:58 PM   #3
Chris3Duke
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Thanks for the DIY. I think my thermostat is bad, as I was driving home from NYC to DC last week in cold weather, and the engine sat at about 1/4 temperature (instead of 12 o'clock) the whole drive back.

I may as well do a coolant flush while I'm in there. How about the water pump? Any sign that's going bad, or is it preventative maintenance. My car was built October of 2001, and has 116k miles on it.
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Old 02-13-2012, 11:55 PM   #4
bimmerfan08
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Quote:
Originally Posted by Chris3Duke View Post
Thanks for the DIY. I think my thermostat is bad, as I was driving home from NYC to DC last week in cold weather, and the engine sat at about 1/4 temperature (instead of 12 o'clock) the whole drive back.

I may as well do a coolant flush while I'm in there. How about the water pump? Any sign that's going bad, or is it preventative maintenance. My car was built October of 2001, and has 116k miles on it.
When my water pump went bad, I had coolant spray in the engine bay. The water pump shaft will become loose...this is noticeable by grabbing the fan and noting the amount of play in it. Also, the water pump was making a grinding noise due to the bearings beginning to seize up.

Heres my thread with pictures pinpointing the source of my coolant leak and a bad water pump.

http://www.m3forum.net/m3forum/showthread.php?t=393436

Just as a reference, my car was a 2002, build date of 11/01 and had a water pump stamp date of 12/01. My thermostat was stamped 07/01. I have no doubt these were the original parts on the car. I had 103,5XX miles when the water pump decided to crap out about 3 weeks ago. Thermostat still functioned well but I replaced it anyhow.
__________________
"In any system with finite resources and infinite expansion of population—like your business, or like all of humanity—innovation is essential for not only success but also survival. The innovators are our leaders. You cannot separate the two. Whether it is by thought, technology or organization, innovation is our only hope to solve our challenges."

Last edited by bimmerfan08; 02-13-2012 at 11:59 PM.
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Old 02-13-2012, 11:58 PM   #5
bimmerfan08
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Oh and Mike from thebmwpartstore.com sells the OEM M3 thermostat for $29 a pop.
__________________
"In any system with finite resources and infinite expansion of population—like your business, or like all of humanity—innovation is essential for not only success but also survival. The innovators are our leaders. You cannot separate the two. Whether it is by thought, technology or organization, innovation is our only hope to solve our challenges."
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Old 02-14-2012, 04:13 PM   #6
Chris3Duke
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Hmm. At $300+ for the pump, I probably won't replace it until it goes bad. But I am going to do the thermostat.
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Old 02-15-2012, 11:51 PM   #7
bimmerfan08
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Quote:
Originally Posted by Chris3Duke View Post
Hmm. At $300+ for the pump, I probably won't replace it until it goes bad. But I am going to do the thermostat.
Yeah I would just wait on the pump. Cheapest is $325 shipped. The thermostat can be swapped right from the top of the fan/belt area.
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"In any system with finite resources and infinite expansion of population—like your business, or like all of humanity—innovation is essential for not only success but also survival. The innovators are our leaders. You cannot separate the two. Whether it is by thought, technology or organization, innovation is our only hope to solve our challenges."
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Old 02-02-2016, 01:24 AM   #8
cscdavid
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Thanks and it helps a lot
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