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XBimmers | BMW X3 Forum BMW X3 and X4 Forums | F25 (2011 - 2017) | F26 (2014 - Current) Second Generation BMW X3 (F25) General Forum X3 F25 Water Pump & Thermostat DIY (N52)

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      11-22-2019, 07:48 AM   #1
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Drives: 2009 328it
Join Date: Oct 2013
Location: Atlanta

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X3 F25 Water Pump & Thermostat DIY (N52)

Note: This is my attempt at adding to the overall knowledge on the interwebs. Use at your own risk.

This project took me two full days in a conditioned garage w/ plenty of tools at-hand. Master mechanics who have done this a dozen times can do it in 5hrs, that ain't me! This is the 1st of several entries.


PREP- I don't know about you, but I need pictures! I taped and assembly pic of the water pump and tstat to the hood!
Start by removing the airbox & fan shroud. Why the airbox? Trust me, it frees up valuable room to remove and muscle the fan shroud and trans oil cooler. I only removed the airbox in a frustrating attempt at installing the oil cooler at the end, wish I had done it sooner.
Jack the X3 (passenger side) remove splash guard. Lower again to wrestle w/ the fan shroud and such. When done w/ those, raise and remove passenger wheel. Place a jack stand under the suspension frame. (20min)
Airbox (5min) - disconnect the MAF sensor. Loosen hose clamp w/ 6mm nut driver. Pull entire airbox assembly straight up.
Cross Brace (10min) - T-30 & T-40 Torx. 3 T-30 in the middle and 8 T-40 on the ends. Easiest step you'll see, enjoy it!
Fan Shroud (over 1hour on my 1st attempt. 10min on my 2nd)- A single T-25 torx holds the shroud on the top left (all my instructions are facing rearward, yeah non-standard). Unclip the electrical connector on the left. Remove the T-25 holding the transmission oil cooler on the right. Pry the top metal tab to the right and push down on the oil cooler to unclip it from the fan shroud. NOW... there's a plastic clip locking the right side of the shroud. Easiest way I found to release this was to jam a large standard screw driver between the tap and the clip (took me a long time to mess w/ this clip) Yank the fan shroud straight up. This TIP will save you considerable time. Tilt the right side of the fan shroud up to clear the 1st large plastic mounting tab past the radiator hose. Lift more, then tilt the left side up to clear those mounting tabs. ALSO, the shroud gets jammed between the radiator side lips, push it rearward to allow you to tilt one side and then the other. The oil cooler will resist pushing back, but the extra space from removing the airbox really helps here.
Drain the Radiator. (20min) Not obvious, but there is no drain plug. You have to remove the driver's side lower hose to drain the radiator. Standard BMW spring clip connection. Pry the clip open w/a small flat head. Hose came off fairly easily. Take note of how much comes out to replace w/ same quantity. About 11/2gallons drained from mine. Afterwards, I noticed a green arrow on the bottom hose ends that must be BMW's way of saying this is the drain port ;-)

THERMOSTAT- now the fun really begins! (2hrs)
1. Remove electrical connector 1st (5min) I did this from underneath. I depressed the release w/ one finger and fried downwards w/ a flathead to get it to come out. Very tight space.
2. Remove the quick disconnect hoses (10min) Just enough room to get a small flathead in there and release the spring clips. Both came off very easily reaching down from the top. , ,,
3. Remove top hose clamp w/ a 6mm ratchet from the top. Again, hose didn't take too much coaxing. (5min)
4. Remove bottom hose clamp from underneath the car &/or wheel well. Pretty good access. (10min) ,
5. Unbolt the thermostat from the water pump. (15min) Two 10 mm bolts removed from the bottom. The front I removed w/ a 1/4" drive and 6" extension. The back bolt is a bugger. I had a 10mm offset box
wrench on hand and worked it loose one small turn at a time. The 2nd time I took it off (more on that later), I bought a ratcheting 10mm box end wrench w/ swivel. Heck yeah!
6. Yank the TStat out from the top. Half way there! Well, almost. The TStat I purchased did NOT match the one that came out. Luckily, BMW of South ATL is just 15min away :-/

WATER PUMP (1.5hrs)
1. Disconnect electrical connector(15min). Release clip is on the backside. I had to do some prying to get it off.
2. Loosen 6mm hose clamp from bottom of car. Universal joint was needed.
3. Unbolt water pump from engine block. (20min) An E-12 fit on the front bottom torx w/o any problems. However, use a 10mm ratcheting box end wrench to get the other two off. Access both from the
front/top of the car. Basically working by feel here.
4. Remove water pump to engine block hose (45min). This was the toughest hose of the bunch! Also why you unbolt the water pump 1st. This hose is only a couple inches long between the water pump and
aluminum engine block pipe. It took LOTS of prying w/ a flat head from all angles to get this hose to finally let go. I had to pull on the pump while prying to get it to release.
5. Remove water pump from the top.

I had at least 5 hours into this on the 1st day and it was time for a break!


Last edited by Beberle; 11-22-2019 at 08:53 AM..
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      11-22-2019, 08:53 AM   #2
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Drives: 2009 328it
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Day 2

Hopefully you got a good night's rest from day 1 and not too many nightmares!

INSTALLATION (31/2hours)

Water Pump (11/2hours)
1. Install new water pump-to-thermostat hose in the same orientation & angle as the old pump.
2 Install the water pump from the top. Align and fit the water pump onto the engine block hose. Remember, this hose doesn't have much movement, so the pump needs to be worked onto the hose. It was fussy for me.
3. Tighten the hose clamp from the top/front of the car w/ a 10mm nut driver and extension.
4. Bolt water pump to engine block.
a. Lift on the front of the pump and feed the bottom front torx bolt into place from underneath the car. Finger tighten. Remember to use NEW aluminum torx bolts. Most come w/ the water pump.
b. Finger tighten top torx from the front.
c. Insert rear torx bolt. It's not steel, so I couldn't use a magnetic pickup tool to help. Instead, I finally did this :-) Tighten the rear torx w/ the 10mm box end ratchet from underneath the car.
d. Tighten the remaining two from up top. Torque specks basically say snug, then tighten 90deg. That was about 3 ratches on my wrench w/ limited space.
5. Connect electrical plug. Very little slack in the wire. I finally fed it starting from the bottom lip and worked it on.

Here's where I messed up. Sure, I tightened the hose clamps on the water pump. However, the hose clamp going to the engine block was crooked. The back side was actually off of the hose and almost impossible to see... until you start adding fluid and watch a slow leak start dripping from under the car :-/ Triple-check before proceeding.
1. I've read about people using assembly lube on the thermostat fittings to make connections easier. I used Gummi Pfledge from BMW. If it's good enough for window weather stripping ;-) It seemed to do the job!
2. Install the two quick-disconnect hoses from up top. Almost too easy at this point! Pull on them to make sure they're locked in.
3. Mount the thermostat to the water pump. I used a magnetic pickup tool to get the back 10mm bolt into place. This is done from underneath.
4. Connect smaller top hose working from top of car. 6mm nut driver from the front is an easy reach.
5. Connect the water pump to thermostat hose from wheel well. I thightened the hose clamp from underneath the car.
6. Plug in the electrical connector from the wheel well.

Before proceeding, now is probably a very good time to change your serpentine belt. It takes a T-60 Torx to loosen the tensioner pulley. I looked at my records... I had well over 100,000 miles on mine and it still looked in good shape!

1. This tip will save you a LOT of time. Lower the fan tray starting w/ the left side. Once the left mounting tab is past the radiator pipe, shift the tray to the left and slip the right tab past the right hose fitting. Try not to let the tray jam between the radiator core flanges, keep it rearward.
2. Oil cooler: You THINK you're done! I took me over half an hour to finally get the oil cooler to fit into the fan tray slot. I finally took out the airbox to give myself the leverage to push the cooler tab into the fan tray slot. Here's a picture of the slot from the back.'s very little hose slack on the oil cooler. I had to hold the fan tray about 3" up, which aligns the tray slot w/ the cooler tab. You need to push the cooler firmly against the tray while then lower the tray to set the tab. Easy.. not! Fan tray will Click into place w/ bottom tabs and the right locking tab.
3. Install torx screws on top of fan and the oil cooler.
4. Plug in the electric fan connector.
5. Fill the reservoir. I took out 11/2 gallons of coolant and put 11/2 gallons back in. This is where I noticed the leak coming from the bottom of the car. I restrained myself from throwing tools. It IS possible to unmount the thermostat and reach the now-hidden hose clamp on the water pump to engine block. It took me well over an hour to remedy the situation... with coolant dripping on me the entire time. Don't be me!
6. Bleed the system. There are plenty of youtube videos and DIYs on how to do this. Surprisingly, mine only took about 4 minutes. I thought something was wrong and did it again, but it only ran for 30 seconds. I ran the X3 for 15 minutes to check for leaks or overheating w/ no isssues.

That's it folks! The right tools and a LOT of patience, and you can save yourself close to $1,000. I'm much less intimidated about doing the same on my 2009 328i wagon w/ 140k miles now. I'll give it a couple weeks however ;-)


Last edited by Beberle; 11-23-2019 at 07:21 AM..
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      11-22-2019, 09:17 AM   #3

Drives: 2012 F25 X3 28i (N52)
Join Date: Sep 2018
Location: California

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Ok Brian, thanks for the details. I'm just completing new VC gasket install, taking much more time than I envisioned on my 6 cylinder motor.

I've seen where the pump and stat are located- when it's time for this work I will be paying Mr Mechanic to do the job.

Nice work/Good luck!
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      12-02-2019, 07:14 PM   #4
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Drives: 2018 X3 M40i, 2012 X3 Xdrive35
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Nice write up. I did mine last year and it took me a weekend also. I consider myself a pretty good mechanic and had nightmares reading your instructions. I spent a long time getting the water pump and thermostat oriented correctly in the small confine. Not sure who designed this mess.
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