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DIY: Stewart Water Pump + Expansion Tank + Coolant Change + 2 Tensioner Pullies

254K views 217 replies 98 participants last post by  paraklas 
#1 ·
Here's my complete DIY..

EMP Stewart Components + Expansion Tank + Coolant Change + Tensioners

After 2 years, I decided to do a complete coolant change. So I took the opportunity to replace my expansion tank as well since it was leaking a bit from the top part. Coincidentally, my water pump decided to fail too by making a "hiiissshhhiiiin" sound once warm, indicating worn bearings. Not wanting to throw a belt or something I chose to replace it with the high performance/flow water pump with stainless steel impeller & high durability bearings from EMP Stewart components. More expensive than the OEM pump but at least one less thing to worry about. Since I would have to remove the belt to access the WP, I grabbed the opportunity to replace both deflection pulleys from the tensioners. It was a good thinking because after I removed the belt I noticed a lot of free play in both tensioner pulleys, another indication of pending failure.

Considering that almost all of the affected components are either made from composite materials or aluminum, I followed the exact torque specs found in BMW TIS to avoid snapping things. You NEED a torque wrench from 10Nm and up.

Torque Specs:
Drain Plug on Engine Block: 25Nm
Pulley on Water Pump bolts: 10Nm
Water Pump on Block nuts: 10Nm
Deflection Pulley on Tensioner: 35-40Nm (I could not find specs for the tensioner pulleys so I measured the approximate value with my torque wrench)

Part List:
EMP Stewart Components BMW E46 High Flow Water pump
4L OEM Coolant
4L Distilled Water
Bleeder Screw
Expansion Tank drain plug (blue)
Radiator plug (blue one, different for auto/manual transmissions)
Coolant Drain plug washer
Expansion Tank
(For exact part numbers go to http://bmwfans.info and enter last 7 digits of chassis number to get the correct part)

DIY:
If you want to replace the thermostat now it's a good chance! Also, remove the lower splash shield to access the components below. Use a set of ramps or jack stands - NEVER USE THE OEM JACK FOR SUCH WORK.




Belt diagram to remember the path!!! Not exactly CAD design but does the job:p


The new pump looks beefy and well designed


New expansion tank


Fan removal (Manual transmission). Remove air intake by popping the 3 push/lock pins. Remove the push/lock pin on the right side of the fan


Remove both plugs and the T25 torx screw on the left. Lift it and it's out of the way. 5 Minutes!!


To remove A/C Belt, insert a 16mm spanner on the illustrated bolt and rotate counter clock wise to compress the spring.


When the 2 holes shown below are aligned, insert a metal rod like an allen key to hold the spring compressed. Now remove the A/C belt


Pop the protection cap from the pulley and insert a T50 bit and remove the bolt. The pulley just drops. Replace it with new one and tight back to 35-40Nm. Re-install protection cap and you are done!


Remove airbox to allow access to the various hoses beneath. Remove 2x10mm bolts on the airbox, disconnect MAF plug and the clamp that holds it to the rest of the intake boot. You need to access the hose below that goes in the expansion tank.


Time to remove the main engine belt and the tensioner. Again insert a 16mm key with a small extension to prevent ratchet touching the crank pulley and rotate clockwise to compress spring. Once compressed, slide engine belt out of the pulley and release the tensioner. Pop the protection cap from the tensioner, insert T50 bit and remove the deflection pulley, just like the A/C one. Install new one and tight back to 40Nm. Don't forget the protection cap.




Time to do the expansion tank now.

1. Let engine cool down
2. Remove expansion tank cap & bleeder screw
3. Go below car and remove expansion tank drain plug (blue) and let the coolant drain in a bucket. Do not allow pets in the area, coolant is sweet and if your dog drinks it, he will die.
4. Remove coolant level sensor. Unplug it and twist it 45 degrees for removal.
5. Remove expansion tank quick release spring


Remove plastic bleed screw, radiator cap and 2 quick release springs from upper radiator hose.

I had to spray some WD-40 on the hose to tank & radiator connection to soften the seals because they were almost glued in place. Let it soak for 5 minutes and job becomes much easier.


There's another hose that needs to disconnect and is the lower one from the heater valve. Lift quick release spring and wiggle the hose out of the tank. Stand on top of the tank, place both hands on the bottom of the tank and lift upwards shaking it a bit. I had to put some strength to get the tank out mainly because of the bottom connection being stuck. Remember to catch any coolant. Once the old tank is removed, I inserted the new one in place, lubricating its seals with undiluted coolant. Once in place re-install all the hoses, drain plugs, and connectors. One step completed at a time. The only thing left not in place was the bleed screw because I would add coolant later.


Next step was to drain the radiator from old coolant: Remove the small blue plastic screw and allow coolant to drain completely.


Draining coolant from engine block. Go below car and locate the drain plug. It's next to the ground strap behind the cat converter. You need a ratchet wrench with a u-joint and a couple of extensions. I couldn't take pictures because both my hands were occupied. The drain plug needs a little force to break free and once removed a lot of coolant will flow. It was that time that I discovered the taste of coolant too. It's part number 4 and washer part 5. Once coolant stops running, replace washer and re-install plug. Torque to 25Nm.


Engine drain plug with its washer


The final step is to remove the actual water pump. Locate the 4 bolts that hold the composite pulley on the water pump and remove them. The pulley just slides out. Don't drop it or hit it because it looks (and probably is) fragile.


To remove the exposed pump, remove the 4 nuts that hold it on the engine block. If it's stuck in place, thread 2x M6 bolts evenly on the water pump. Once they touch the engine block screw them evenly until they break the pump free. Pull the pump and collect any remaining coolant.


New (Left) Vs old (Right) pump. The OEM pump looks like a toy next to the Stewart one. I could spin the old pump hearing the shot bearings inside rattle. Lasted 80000km.


And that's it basically. Installation for the water pump is exactly the opposite of removal. Once installed, I re-inserted main engine belt, a/c belt, fan and airbox with MAF. I inspected everything in case I forgot to connect a part and started the coolant refill and vent process.

1. Mix 50/50 OEM coolant with distilled water (4L+4L) 8L total
2. Set ignition to ON (engine off) position, set the heater fan to lowest speed and temp setting to max (32 degrees) this will open the heater valve for proper bleeding.
3. Slowly pour mixed coolant inside expansion tank until bubble free fluid emerges from bleed plug. I needed around 7.5 Liters of coolant.
4. Screw bleed valve in place
5. Start engine and allow it to operate until warm (thermostat opens)
6. Watch for any leaks and also watch the temp gauge. If it goes beyond middle turn engine off and check for air pockets and re-bleed system.

End result:


Once everything is working properly, re-install lower splash cover and enjoy your car!

Total time: 5 hours.
Useful procedures from TIS (Converted to PDF):

Water Pump Replacement

Draining & Adding Coolant

Venting Cooling System
 
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#166 · (Edited)
#169 · (Edited)
Thanks.. Going to do it this weekend. Really getting into this :) fixed my oil housing gasket myself. The Power steering return hose was leaking and I fixed that. Did my brakes. Starting to become a hobby. Still debating to do transmission or not because I keep getting mixed reviews about how changing it could cause problems since my car has 105K miles and it's never been changed. I don't want to open up a can of worms. I called several BMW and they said the texaco ATF last 250K which I believe is not available anymore and if I do change it , it could cause failures and I would going forward have to change every 30K. I don't know who to believe.
 
#172 ·
Starting to become a hobby. Join the club! That's what most of us here do!
Still debating to do transmission or not because I keep getting mixed reviews about how changing it could cause problems since my car has 105K miles and it's never been changed. I don't want to open up a can of worms. I called several BMW and they said the texaco ATF last 250K which I believe is not available anymore and if I do change it , it could cause failures and I would going forward have to change every 30K. I don't know who to believe.
If you intend to keep this car a while, I'd strongly consider doing your fluid change. It's still young enough so no damage is done, and you'll then be operating with as little incremental wear as possible from now on.
And if you change fluid, you'll certainly not be obligated to change frequently into the future. Use the best quality fluid you can find.
 
#170 ·
I did the first transmission change at 70k miles, with Redline MTL. Ultra smooth shifts for a year or so. Second change was with OEM BMW MTL-LT-02 which I didn't like so much because of the effort required to shift specially when gearbox was cold. So my next change will be again with Redline again
 
#182 ·
Just found this DIY and set it to favorites!

I can hear my pulleys making noise now that the temps are getting colder. I was going to do these soon and ordered the parts from Pelican... But then I started thinking about the water pump... Then the hoses... Then the expansion tank, etc...

I also want to look into replacing the manual clutch fan with the electric fan. My thoughts right now are that the auto has two fans (maybe) for a reason. From what I have read... You remove the clutch fan and the front ux fan on the automatic versions and then you install the electric fan using the sensor from the front fan. I would assume that the front fan, on an automatic, would turn on at times that it as about to overheat. (IE, the clutch stopped working correctly.)

If you replace the clutch fan with an electric fan using that logic... The new electric fan would only come on at the preset temp saying the car was in overheat mode. Is this correct?

Can anyone shoot holes in that logic? (Please!) I'd like to upgrade but am unsure because of this.
 
#183 ·
Im stuck removing the belt

I am replacing my water pump and cant figure out out to get the belt off. the first one was fine, release tension with the spring no big deal. this one I feel is different than the videos, I dont have a 16 mm in that spot i was using a 14 and that even did nothing. I have a coupe, 5 speed? and help. thank god i have the day off
 

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#184 · (Edited)
I am replacing my water pump and cant figure out out to get the belt off. the first one was fine, release tension with the spring no big deal. this one I feel is different than the videos, I dont have a 16 mm in that spot i was using a 14 and that even did nothing. I have a coupe, 5 speed? and help. thank god i have the day off
It's under the dust cap on the pulley in the middle of the big ones. Also, this is probably a 45 torx if I remember it correctly.
 
#188 ·
Alright guys, I got the belt off but not my loosening the tension, now i still need to learn how to loosen the tension to get it back on, my car is in pieces in the driveway and I have to cancel my big plans tomorrow now =(

please help me guys, I have put a wrench on all the bolts/nuts IDK! nothing is giving me tension, I tied the allen, the i think it was either 14 or 11mm socket. what am i supposed to do nothing is giving me tension??
 

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#190 ·
Did you take the belt off? It goes back on the same way. Did you route the new belt the same way?
The hydraulic tensioner defaults to the tightest position. Get the belt in place and wrench the tensioner to a 'looser' position. Ease the belt back over the idler, and release the wrench slowly.
If this does not help, you need to write down much more info so we can spot what you are doing wrong. We have done this before and it works fine and is easy if you're doing all the steps correctly.
 
#189 ·
I thought there was a smaller area to put a wrench on to untorque the tensioners?

I am doing a complete cooling system overhaul this weekend so I will follow this...

OP... Have you checked out pictures on the Internet of tensioners that are NOT installed so you can get a good look at how they work? As I recall.. There is a 5/8" spot to get a socket on to undo the tension...
 
#192 ·
Take a look at your picture where you labeled ' the bolt does nothing'.. This is ur hydraulic tensioner.. on one end of the tensioner, there's a pulley.. This is the one that will relieve the tension. This is the one you labeled 'This pulley does nothing in any direction'.. There is a lot of tension on this one. YOu will need a breaker bar.. Go clock-wise to relieve the tension. You will see the entire pulley moving as it relieves the tension.. REmember, it is a high tension..
 
#197 ·
Hey Guys, I know this is old thread, but I found the OP DIY was quite nice. I think my water pump is leaking on my M54B25 E60. So I am planning to doing this project myself. Question I have is from the bentley manual for E39 with same egine, it says;
"Be sure to replace sealing O-ring and gaskets"

Which gasket are required to be replaced for water pump, as I know of only the O-Ring.

Also, before installing the O-Ring it is recommend to use water based lubricant, does anyone know what I can use?
 
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