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littleE46 02-05-2011 07:50 PM

DIY Complete X3 Cooling System Overhaul
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I was planning on doing this as preventative maintenance in the spring but the X3 had different ideas. It started leaking coolant, luckily the engine never overheated.

Here's the parts list for a 2004 X3 3.0 automatic and the prices I paid. Total was $846.89.

11-53-3-400-207 Coolant Hose $34.58
17-12-3-413-819 Coolant Hose $57.02
11-53-3-400-205 Coolant Hose $24.33

17-11-3-400-013 Radiator $179.75
17-13-7-787-039 Expansion Tank/Coolant Reservoir $37.76
17-11-1-742-231 Radiator Cap/Expansion Tank Cap $10.82
17-11-1-712-788 Coolant Bleeder Screw; Brass $3.66
17-11-1-707-818 Water Drain Plug $4.75
17-11-1-437-361 Radiator Drain Plug $3.50
17-11-1-437-360 Radiator Drain Petcock; Adjusting Screw $5.43

17-11-1-437-362 Expansion Tank Thermostat $53.25
17-11-7-506-601 Coolant Level Sensor $17.76
13-62-1-433-077 Temperature Sensor $16.50

11-53-7-509-227 Thermostat $60.64
11-51-7-527-910 Water Pump; (Stewart High Performance) $176.70

11-28-1-706-545 Serpentine Belt/Ribbed Drive Belt $18.15
11-28-7-512-758 A/C Belt Tensioner $56.00
11-28-1-748-131 Adjusting Pulley $17.25
11-28-7-516-847 Belt A/C Compressor $24.00
11-28-7-512-762 Belt A/C Compressor $9.75

07-11-9-963-200 Engine Drain Plug Crush Washer $1.28
82-14-1-467-704 BMW Engine Coolant $31.82
Distilled Water $2.19

Most of the parts are pictured below. I'll follow up with separate posts for each section of the job.

littleE46 02-05-2011 08:29 PM

Tools Used
Here is a list of all the tools I used for the project.

Torque wrench
Floor jack and 4 jack stands
Breaker bar
Extension bars
Speed handle
3/8" universal joint
1/2" to 3/8" adaptor
Magnetic pickup
Small pry bar
Plastic mallet

8MM - Engine splash shield
10MM - Water pump, thermostat bolts, air box
13MM - Thermostat bolt to engine hook
16MM - Alternator tensioner pulley,
17MM - Wheel nuts
19MM - Wheel nuts with locks
22MM - Radiator adjusting screw

25 Torx - Radiator
35 Torx - Intake ducts
45 Torx - Water pump tensioner pulley, alternator deflection pulley

Might have been a few other odds and ends that I can't think of.

littleE46 02-05-2011 08:49 PM

Step 1 - Jack up the car
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First loosen the lug nuts on the front passenger wheel. This is the only wheel you need to remove.

Then jack up the front and put jack stands under the front jack pads. This was much easier than my E46 because there is a central jacking point at the front in the middle of the plastic engine splash shield.

Jack the back end up using the cross member INFRONT of the diff and put jack stands under the rear jack points.

Unscrew the 9 bolts holding the plastic engine splash shield using an 8MM socket. Then using a small pry bar remove the plastic expansion bolts at the back of the shield.

littleE46 02-05-2011 09:09 PM

Step 2 - Drain the coolant
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Make sure the engine is cool before proceeding. If it's warm go have a break and come back in a couple of hours.

Turn the ignition on without starting the engine. The turn the heat all the way up with the fan at the lowest setting.

Remove the expansion tank cap and the bleeder screw on the upper rad hose. Put your drain pan (forgot that in my tools post) directly under the expansion tank and unscrew the two blue radiator drains. Wait until the coolant stops flowing.

Next you'll need a 13MM socket on a universal joint with several extensions so you can get to the engine drain plug behind the passenger wheel. Use a breaker bar to start the bolt then you can remove it by turning the extensions by hand. I used a magnetic stick to grab the drain plug. Put the drain pan underneath before you remove the bolt, but be prepared to move the pan as it splashes around when it hits the skid plate.

Don't forget to retrieve the drain plug.

littleE46 02-05-2011 09:33 PM

Step 3 - Remove air box
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Next remove all of the plastic air intake parts so we can get at the cooling system.

Start by removing the four torx bolts for the plastic intake duct at the front of the engine compartment. Remove the intake duct to get to the four torx bolts for the air duct. Before removing the air duct you need to undo the 5 clips holding the top of the square air box and the two clips holding the mass air flow sensor to the air box.

With the air box loose you can separate it from the air duct and remove both of them.

Using a 10MM socket remove the two bolts holding the bottom of the air box down. Separate the wire connector at the back of the air box and then remove the air box by easing it out from the back, lifting up and out.

littleE46 02-05-2011 09:51 PM

Step 4 - Remove the radiator fan
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Now we need to get the electric radiator fan out of the way. Luckily this one is electric, I was thinking automatics had one with a fan clutch attached to the water pump pulley.

Start with the torx bolt to the left of the fan. Then unclip the electric connection to the fan right beside it. On the right hand side use a small pry bar to remove the plastic expansion bolt. Once you remove the F AUC sensor on the top right of the fan just pull the fan straight up and out. You might have to jiggle it to get around the expansion tank.

littleE46 02-05-2011 10:16 PM

Step 5 - Remove belts
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With the rad fan out of the way there's enough room to remove the belts.

To get the a/c belt out, remove the cap on the lower deflector pulley, use a 45 Torx with a large breaker bar to remove the tension then ease the belt off the pulleys.

To get the water pump belt out, use a 16MM socket on the tensioner with a large breaker bar to release the tension. If you have a short thick nail, insert it when the holes align on the tensioner to keep the pressure off. Remove the cap on the tensioner pulley if your replacing the pulley.

Also remove the cap on the deflector pulley if your replacing that one.

littleE46 02-05-2011 10:40 PM

Step 6 - Disconnect wiring
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Next remove the wiring connected to the parts we're replacing. Disconnect the thermostat, pulse generator and vanos connectors then move that wire bundle out of the way. Near the bottom of the lower rad hose is the temp sensor connection.

At this point I would have also removed the coolant level sensor connection on the bottom of the expansion tank. However, the suspension on the X3 won't really allow access from below like an E46. I left this one until later, but it wasn't that easy.

littleE46 02-05-2011 11:07 PM

Step 7 - Remove hoses
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With a flat head screwdriver (missed that in my list) popup the wire connectors that fasten the various hoses to the expansion tank, radiator, thermostat and engine block. Wiggle the upper rad hose away from the expansion tank, I used a large flat head screwdriver in various places to pry them apart. Then you can wiggle and pull the upper rad hose off the thermostat and remove it. Wiggle and pull down on the lower rad hose to separate it from the thermostat, then you can pull the hose away from the radiator.

Now look down just to the left below the expansion tank and you'll see the oil heat exchanger. There is a clip with a tab in the center at the top. Pull up on this to free it then wiggle the three connections loose (I think I used a screwdriver to pry this off). Just leave the heat exchanger resting on the suspension parts below.

Carefully pull the heater hose away from the expansion tank. Assuming your not replacing this one be very careful. I can't see an easy way of replacing this hose without removing the intake manifold so careful, you don't want to damage the plastic end.

Now you can separate the coolant hose that connects to the engine block. I would have also removed this from the expansion tank but again there is little room to get at this from below.

CleanKM 02-05-2011 11:21 PM

Fantastic write up! Thanks!

littleE46 02-05-2011 11:39 PM

Step 8 - Remove radiator
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Ok. Now for the complicated part. Removing the radiator, which would be really easy except that we didn't get the one coolant hose off the bottom of the expansion tank and we didn't remove the coolant level connection.

To start with remove the two plastic screws at the top of the radiator. Then remove the second torx bolt holding the rad to the transmission cooler. At this point you can pull up on the radiator but you'll need to stop part way and reach under the expansion tank to remove the coolant level sensor. Have a look at your replacement expansion tank and sensor to see how this works. You have to twist it and then pull down, then remove the electrical connection. But there is still that last coolant hose in the way. I left it intact but feed the hose through as I remove the rad and expansion tank.

You need to be very careful with this unit because even if you are replacing both the rad and expansion tank, there are many pieces attached to the rad that you need to remove and transfer to the new rad.

Again this was the most difficult part so once you get this far everything else is easy.

littleE46 02-05-2011 11:43 PM


Originally Posted by CleanKM (Post 5827983)
Fantastic write up! Thanks!

Thanks man. I'm not done yet and it's almost taking me as long to write up as it was to do the job. This was my second M54B30 cooling system overhaul. This time I kinda just jumped in and did it from memory. I like taking all the pictures because it slows me down and makes me think about every step. Less likely to make mistakes that way.

littleE46 02-06-2011 12:14 AM

Step 9 - Remove thermostat and water pump
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To remove the thermostat there are three 10mm bolts and one 13mm bolt, with the bolts out give the thermostat a clockwise twist before pulling straight out.

The water pump is a little more tricky. If you forgot to loosen the four bolts on the pulley before removing the serpentine belt, like me, then you'll probably have to put it back on to put some tension on the pulley. With the pulley removed, start by removing the four 10mm bolts on the water pump. To get the pump out you need to take 2 of the long 10mm bolts from the thermostat and thread them into the two threaded holes provided on either side of the pump. Tighten the two bolts evenly and this will begin to force the water pump out of the engine block. Once you can see the large O ring, you should be able to slide the pump out.

You can see in the pictures the lousy plastic impellers from the original stock water pump. The high performance Steward replacement is a much better design for maximum peace of mind. I'm not sure how easy it is to remove all the pieces when a plastic impeller implodes inside the engine.

Anyways, that's about it for removal...except for replacing the tensioner pulleys. The next step is rebuilding the radiator.

littleE46 02-06-2011 01:03 AM

Step 10 - Remove parts from old radiator
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With the old rad out we need to remove the parts we need.

Unbolt the torx screws that hold the mounting plate to the radiator. Use a large flat screwdriver to separate the expansion tank from the mounting plate. Slide the cooling water collector out of the mounting plate. Finally unclip the black plastic mounting strip on the bottom of the radiator.

littleE46 02-06-2011 01:13 AM

Step 11 - Attach mounting plate
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To attach the black mounting strip to the bottom of the new rad, place the front edge (towards the front of the car) of the strip in first. Then squeeze the clips on the back edge to force the strip in place.

Next slide the mounting plate into position making sure the top edge fits over the lip at the top and the bottom edge fits under the tab in the black strip.

Replace the there's your problem. My old thermostat had self destructed, I wonder if that cause the leak...hmmm.

Replace the two torx bolts that hold the mounting plate to the rad.

littleE46 02-06-2011 01:21 AM

Step 12 - Replace the cooling water connector
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The cooling water connector has the blue drain plug for the expansion tank. Unscrew this completely then pull hard on it to remove it from the connector. Replace with a brand new drain plug, for $3 it's not worth doing this job and leaving in the old one. Then slide the connector back onto the mounting plate.

Make sure the clamp for the oil cooling heat exchanger is in the released position to help when reinstalling the rad.

littleE46 02-06-2011 01:31 AM

Step 13 - Install new expansion tank
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Next step is to install the new expansion tank. First attach the expansion tank clamp from the old expansion tank and make sure the clamp is in the released position. Now position the tank so the hook on the back is aligned with the slot on the mounting bracket. Push the tank back towards the rad and down onto the thermostat. Push the clamp in place to hold the tank.

Install a brand new coolant level sensor, insert it in the bottom of the tank and twist counter clockwise into position.

littleE46 02-06-2011 01:43 AM

Step 14 - Replace rad drain
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The new rad came with two different radiator adjusting screws, a short one for standard and a long one for automatics. For me the long one was right. :rofl:

Install a brand new blue plastic drain plug in the adjuster and push the adjuster into the bottom of the rad. Note that for this particular radiator there was one side of the adjuster with a notch cut out that fit a notch on the bottom of the rad. There are also two notches sticking out of the adjuster that fit into to slots in the rad. You need to push the adjuster in very hard so I gave it a few taps with a plastic hammer. Once its all the way down use a 22mm socket to give it a twist and lock it in place.

littleE46 02-06-2011 01:50 AM

Step 15 - Hose assembly
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Finally, install a new temperature sensor in the new lower rad hose and a new drain plug (I like the brass ones better) in the new upper rad hose.

Oh yeah. Don't forget to replace the crush washer on the engine drain plug with a new one. Not much point in doing all this if it's going to leak from the engine.

littleE46 02-06-2011 02:00 AM

I don't have any pretty pictures for the reassembly. At this point you're all ready to start replacing everything we removed. It's pretty smooth from this point on as long as you have a good torque wrench and the specs.

Here are some of the spec's I gathered up as I was putting it back together. I used the chart in the front of the E46 Bentley manual to calculate torques.

A/C tensioner pulley 10mm 8.8 class = 47Nm using 16mm socket
Water pump tensioner pulley 8mm 10.9 class = 34Nm using 45 torx socket
Deflection pulley 8mm 8.8 bolt = 24Nm using 45 torx socket

Water pump nuts m6 nut 24Nm (from Bentley) with 10mm socket
Water pump pulley m6 bolt 10Nm (from Bentley) with 10mm socket

Thermostat m6 8.8 class = 10Nm with 10mm socket
Thermostat M8 8.8 class = 24Nm with 13mm socket

That's everything I've got...probably could have shown more of the reassembly but I needed to finish before dark. More tomorrow.

UncleJ 02-06-2011 07:42 AM

Outstanding write up! Takes me back to the "olden days" when I was doing stuff like that on my cars. Now I know why I stopped and let the professionals do it.:rofl: Reading between the lines it sounds like the problem was your thermostat self destructing. Never mind it was good to do the rest and now you will not have to worry about that crummy water pump (why BMW can't put a decent pump in I just don't understand, it can't cost them that much more) and the rest of the "plumbing" for as long as you keep the car. Thanks for some great memories!:thumbup:

littleE46 02-06-2011 09:19 AM


Originally Posted by UncleJ (Post 5828343)
Outstanding write up! Takes me back to the "olden days" when I was doing stuff like that on my cars. Now I know why I stopped and let the professionals do it.:rofl: Reading between the lines it sounds like the problem was your thermostat self destructing. Never mind it was good to do the rest and now you will not have to worry about that crummy water pump (why BMW can't put a decent pump in I just don't understand, it can't cost them that much more) and the rest of the "plumbing" for as long as you keep the car. Thanks for some great memories!:thumbup:

Thanks bud. For me in the "olden days" I would have always taken it to my mechanic. I didn't even change my own oil until I picked up an E46 Dec '09. Mostly because I had a mechanic that I really trusted. He did a great job and would never do any unnecessary work. When I got the Bimmer it was gonna cost more cause he would have to learn about BMWs to do the work. Besides parts for BMWs up here in Canada are outrageous.

I decided to try a few basic things myself, always ordering parts online from the US (Pelican Parts, Autohausuz...) using a Bentley manual (awesome) and DIYs on E46Fanatics. It's been so easy I'm determined to do everything I can possibly do myself. Last year I replaced the seals on my Vanos and it made such a difference in my 330ci, that was very satisfying.

For me its been far better to DIY rather than take it to a BMW Steelership where I feel like I need a shower afterwards to wash away the feeling of being raped. :rolleyes:

Honestly I can't believe how easy these cars are to fix. The biggest reason I bought an X3 for the wife was because I new that I could work on the engine. I think BMW has done a great job for their mechanics to charge an arm and a leg for jobs that are really simple.

codog2 02-06-2011 09:20 AM

awesome post - How many miles on the X?

littleE46 02-06-2011 09:39 AM

Step 16 - Bleeding
This step is critical. After all that work you really need to do this right.

To start with again turn the ignition to on with out starting the engine, position 2 I think. Crank the heat all the way up, 32C here in Canada, and turn the fan all the way down but not off. This opens the valves to the heater core so you get coolant in the entire system.

Remove the bleeder screw and radiator cap.

Your gonna need 4L (I think thats a gallon) of BMW coolant and 4L of distilled water. Mix the coolant and water in small batches of 50/50 solution and SLOWLY pour it into the expansion tank. When you get near the end, watch for coolant draining out of the bleeder screw. Keep pouring until the coolant flows out the bleeder without any bubbles.

Replace the bleeder screw and rad cap.

Now start the engine and let the engine warm up. Keep your eye on the temperature guage. If the needle starts to rise above the normal centered position turn the engine off immediately. Go trouble shoot for leaks. I don't really have much advise here because it was flawless on both my overhauls.

Take it out for a nice little drive and enjoy but be prepared to stop immediately if the needle starts to rise beyond normal. Maybe don't stray to far from home right yet so you can walk back if it does not go well.

When you get back let the engine cool completely. I let it sit overnight. Then remove the expansion tank cap and check if you need anymore 50/50 mix.

That's all folk...just keep your eye on the temperature (as always on these engines) and check the coolant level every week (part of my normal routine). :thumbup:

littleE46 02-06-2011 10:01 AM


Originally Posted by codog2 (Post 5828499)
awesome post - How many miles on the X?

It's got 96146 km (about 60K miles IIRC) so it was due for an overhaul. Before we purchased it I noted the expansion tank was datestamped 2004 so I figured the entire system was original. I asked the owner to knock $2000 off the price. Little did I know it was already leaking when I bought it. Of course the overhaul only cost $800. :) The real isssue is whether or not the previous owner let it get overheated.

I choose to replace everything for a couple of reasons. First I didn't know what was wrong and it takes a lot longer to fix if your trying to find the leak. Second I didn't care as much about damaging things as I removed them. Those plastic ends on the rad hoses are a nice fit but they can be a pain to take off without breaking them. Third at that age it's pretty much all shot anyways. I can't believe the expansion tank is original. Fourth it's a fair size job and doing it once for the water pump, then again for the expansion tank, then once more for the thermostat, get the picture. It's really cheaper to do the whole system as preventative maintenance. Fifth peace of mind. From what I understand these engines don't really like it when they overheat. The cost of fixing problems resulting from overheating far exceeds the cost of an entire cooling system overhaul.

And finally I really enjoy working on these engine. From the timestamps on the pictures I put the X3 on jacks at 11:40AM and I put the new crush washer on the engine plug at 4:22PM. By my recollection I started pulling tools out at 10:45AM and everything was put away by 5:30PM. Pretty much a day off where I don't think about developing software (day job) at all, and I complete a very satisfying project. Well worth the price of admission.

Next on my list is to replace the spark plugs and do a compression test so I get a sense of the engine condition. Probably good for another DIY unless I find a specific X3 one already.
That will probably wait until spring. It's pretty wet in Vancouver until late May and I don't have a garage.

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