Guide: Replacing Water Pump and Thermostat - E89 N54 (and radiator)

[Christopher72]

So, your water pump failed? Can you fix this yourself? Yes... if you have the tools and the time. Everything is essentially accessible, and you will need more willpower and patience if this is your first time taking this on. The Z4 isn't my only car, so I could let it sit in pieces while I lived life. If this is your only ride, and you absolutely need this completed in a day -- it's possible, but it's going to be a long day. In honesty, it took me about 1 day of work if I put it all together in actual time spent on this aspect. But that assumes the removal of the time I spent drinking, swearing, and staring at an impasse until I figured it out.

I also replaced a lot of the coolant loop since my car has 90k miles on it and a few other things -- because of the "While you're down there" aspect. I chose metal parts whenever possible.

Parts I used
Water Pump - Pierburg 11515A05704 - Full metal (including bolts)
Engine Coolant Thermostat - Wahler 11537549476
ECS Tuning Aluminized Silicone Water Pump Hose V2.0 008286LA01 (U-hose)
VTT Full Billet/Silicone hose kit - VTT-N54-COOLANT-FULL-BLUE - (everything except u-hose)
CSF High-Performance Aluminum Radiator - 7046 (DCT Automatic)
Cooling O-Rings (2) - 17111711987
2 gallons - BMW Coolant - 82141467704 (mixed 50:50 with distilled water) Z4 takes 2.2 Gallons of coolant, so 1 wont cut it
And a stainless worm drive German hose clamp set

Tools required:
Jack(s), Jack Stands, Lift, Cribs... something to get the car up safely for the work. I used cribs.
Metric ETorx, Torx, & Hex socket set, extensions, socket wrenches (1/4", 3/8", 1/2" drive)
Torque wrenches for high and low Newton Meter measurements
Stubby 6mm ratcheting wrench or flex-head.
Mechanics pick set/pry bars
Coolant pressure test kit
Coolant catch basin for responsible disposal
Safety glasses - antifog
rags to clean up the mess
Flat, level space to work
Something to hold and organize the fifty million screws you will be removing.
Extra 8mm trim screws since I noticed a few missing - 07147129160 (most ubiquitous screw in the car)
Nitrile gloves.

Get a good understanding of where things are first... It really helps when reassembling:
https://www.realoem.com/bmw/enUS/showpa ... Id=11_3972
https://www.realoem.com/bmw/enUS/showpa ... Id=11_3754
https://www.realoem.com/bmw/enUS/showpa ... Id=17_0377


First!
Park your car, apply the e-brake, and get it up on your jack stands, lift, or cribs. You only have to get the front up, but I put the whole car up to get more space underneath. Let the engine cool down for an hour before getting into it.



Steps in order: (ill go into the details of each)
Remove intake duct on intake silencer housing
Remove cross connection.
Remove front underbody protection
Release anti-roll bar on front axle
Release transmission oil cooler from the fan cowl; do not remove.
Remove fan cowl
Remove intercooler (charge air cooler)
Drain coolant, Disconnect hoses, and remove radiator
Remove coolant expansion tank
Remove front right cross-member
Remove coolant thermostat
Remove coolant pump
Reinstall everything in exact reverse order.
Pressure test coolant system
Lower the Z4 off of the stands/cribs/lift back onto the level floor
Fill coolant system and purge the air.
Clear the previous error codes with an ODBC2 tool.
Enjoy your hard work with a test drive

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Remove intake duct on intake silencer housing (2)
Remove four 8mm trim screws - torqued 8 Nm


Remove cross connection.(2)
Remove six Torx bolts - torqued 7.6 Nm
The hood release line a coolant return to resevoir hose are clipped in, but are easily released.


Remove front underbody protection
Remove several 8mm trim screws - torqued 8 Nm. You'll know when you get them all when the underbody protection drops on your head.

There's another lower cover under the fan and intercooler held on by two more trim screws... remove... same torque


Release anti-roll bar on front axle
Remove the 4 self-locking nuts from the stabilizer bar supports -- recommended to replace them (07119905374) - torque 22 Nm
Once the bar is released it swings a bit out of the way to give access to the water pump clamps and screws.


As a side note: Take a look at your bushings and see if they look cracked - mine were. replacing was difficult since mine were bonded to the bar, but not impossible... just hard enough to scrape off that you wish you never started. OEM repair part is 31356765574, I replaced with Powerflex PFF5-4602-26. not really a part of the pump fix, but a while you're down there, look around thing.

Release transmission oil cooler from the fan cowl
To pull the fan cowling up, it must be detached from the oil cooler.
From the bottom of the fan cowl, remove the screw shown as #3 in this picture. torque 7.3 Nm


Remove fan cowl
Unclip the coolant line (1) and disconnect the electrical (2)


Remove screw (1) on fan cowl. torque 4.5Nm.
There's a press lock at (2) that needs to be depressed while you pull up on the fan cowl to remove it.


Remove intercooler (charge air cooler)
Disconnect the air hoses (1) and the screws (2) torque 4.5Nm


Drain coolant, disconnect hoses, and remove radiator
You can drain your coolant from the blue drain plug on the left-side bottom of the radiator if you are replacing the plug or the radiator.
If you're not replacing the radiator or plug, then just drain it from one of the hose connections to the radiator that you will remove. This avoids opening the drain plug and risking any damage to it.
Remove the cap from the coolant reservoir to fully drain.

Please collect the coolant in a capture basin throughout this work. Put it in a sealed container to dispose of properly. In the USA, your county will have a posted schedule and location for toxic fluids collection. This stuff shouldn't be put down a drain or dumped -- big environmental impact. Keeping it closed and cleaning up spills will prevent your pets or other wildlife from consuming this sweet fluid fatally.

https://www.youtube.com/watch?v=6RddnO9p8a8 YouTube of a 335i radiator replacement, which shows draining, disconnecting hoses, and removing the two T25 bolts at the top corners of the rad (1). 4.5Nm torque

Removing the hoses was significantly easier with picks and a pry tool. Keep in mind not to pry against the rad fins - they bend easily. Take a picture of the way the hoses look as they are attached. It's quite an intricate puzzle if you don't. In hindsight, I wish I took more pictures of it! Take a look at your hoses as you disconnect them. If they are swelling, they need replaced. If you have a 100k mile car, just replace your hoses. For the hoses you don't replace in reinstall, replace your O-rings.








Remove coolant expansion tank
The coolant reservoir needs to be removed to gain access and remove the diagonal strut. Inspect the plastic for cracks or degradation. It may be a good plan to replace it if you have a 100k mile car -- plastic doesn't age well in heat. I have an aluminum version on order:https://www.ecstuning.com/b-turner-moto ... 378la02~a/

Remove the two screws (2) 8Nm torque
Remove the two hose connections - pick/pry work well here too -- don't lose the metal clips
Pop the reservoir out of the rubber post -- requires a little force but be careful not to pull it away until disconnecting the sensor on the bottom. I believe it was a press and quarter anticlockwise turn to release.


Remove front right cross-member
As you can see in the picture, the "diagonal strut" is in the way of removing the thermostat and coolant pump.



Remove the 3 circled nuts/bolts - torque 56 Nm
Then thread the metal arm out of the car to get it out of your way. This part isn't carrying load.

Also remove the (2) bolts (7.3 Nm torque) on the front axel support (circled yellow)

This is the end of getting everything else out of the way to actually work on the Thermostat and Coolant Pump..
Take a minute to drink at least a pint. You are a solid representative of DIY mechanics to get this far.

Continued in next post.....

[Christopher72]

Still to be approached:
Remove coolant thermostat
Remove coolant pump
Reinstall everything in exact reverse order.
Pressure test coolant system
Lower the Z4 off of the stands/cribs/lift back onto the level floor
Fill coolant system and purge the air.
Clear the previous error codes with an ODBC2 tool.
Enjoy your hard work with a test drive

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This is the hard part. So glove up, tighten your straps/belt, and tear off a piece of beef jerky to gnaw on.

Remove coolant thermostat
The hose that connects the cylinder head to the thermostat should be disconnected from the cylinder head. The flange at the cylnder head is nicknamed the Mickey Mouse flange for obvious reasons. For some unknown reason, BMW decided to use a plastic flange here and they are prone to failure due to age. I recommend either replacing the flange or the entire hose, and not just replacing the o-ring on reinstallation.

Leaving this hose (2) attached to the thermostat makes it easier to correctly attach the new hose and therm in advance of installation back into the engine bay. So leave it attached to the thermostat... we need easy.

Disconnect (3) and (4) from the thermostat. Dont' lose the clips. Pick and pry bars make this easier. Use eye protection and be ready with the catch basin as more coolant will drain out.



Hose (1) hose clamp can be loosened from the bottom using the space you opened up from lowering the sway bar. (Yellow Arrow)
This is a picture from after the sway bar was reinstalled... so it wont be in your way.

The screws (6) torqued at 8Nm - that secure the thermostat to the coolant pump are also accessible under the bar. (red)


Remove the thermostat electrical connection (5) from the front, and tuck it up out of your way.
The thermostat will now pull out from the front -- you'll have to negotiate the cylinder head hose out -- I had also removed the front air duct from the turbo, so it wasn't in my way, which made this much easier.

Once I had removed the old thermostat. I put it on my bench and used it as a reference for the new parts. I recommend proper hose clamps - don't use cheap ones that cut into your expensive hoses.. OEM BMW clamps work well, but are expensive.. just get another decent clamp with relief on the edges.


Remove coolant pump

You have to release hose (1) by feel from the front. This is where I needed a stubby 6mm ratcheting wrench, and it worked very well. There's not a lot of space in there for tools, and my XL hands don't help the situation. I was stuck here until Amazon delivered a new wrench.


Once the hose clamp is released, unscrew the bolts (4) that secure the pump to the block and immediately toss them in the trash. These are aluminum and must be replaced with the ones in your replacement pump kit with appropriate Nm torque from its instructions, or new BMW aluminum bolts at 10Nm 90deg torque when reinstalled.

As you pull out the pump, disconnect the electrical connection (2)

Use the existing U-hose as a reference for installing a new one on your new pump -- always change this hose because it is subjected to greater temperatures near the block and turbo and will likely be a problem eventually.


I replaced with a full metal pump and an aluminumized silicone U-hose.

While its out on your workbench, fit your pump and thermostat together (screwed together) and orient the hoses and clamps to be sure the u-hose is 'trained' and expanded a little. It's more difficult to do the first fit inside the engine bay. Then detach the parts from each other...

Reinstall everything in exact reverse order.

The pump and thermostat are reinstalled in the exact reverse processes that you just did to remove them... use the appropriate torques. It's the same with every part removed in this process -- follow exactly or the puzzle won't work.

Remember to replace any o-rings from hose connections that you are not replacing.

It's critical that ALL hoses with retainer clips are fully seated and the clip is successfully resting in the notches.
Lubricate new O-rings to make new fittings easier.

If you've trashed screws you replaced along the way -- you won't be wondering why you have extras...

Pressure test coolant system
Use a pressure test kit to check your work. It should hold without dropping. Use a YouTube if you need a guide for your specific kit. They are relatively cheap and much cheaper than having to replace 2 gallons of BMW coolant.



Lower the Z4 off of the stands/cribs/lift back onto the level floor
You're ready to fill, but let's ensure we're level and ready to go have fun after the fillup.

Fill coolant system and purge the air.
I used a funnel that fastens to the coolant reservoir -- borrowed from a friend. This is just a sample, but it makes this a lot easier. The Z4 N54 will take 2.2 gallons of coolant. This is mixed 50:50 with distilled water when using BMW Coolant. (Not RODI or RO water!).

Go ahead and put 2.5 gallons of your 50:50 mix in the big funnel, and then you bleed the system electronically.
Insert the keyfob, and press the start button to put turn your Z4 on --- DO NOT START THE ENGINE.
Turn your temp knob to fully hot and the fan to the lowest setting.
Depress the accelerator pedal for about 10 seconds, or until you hear the pump running.

This bleeding cycle will run for about 10 minutes, and you may wish to attach a trickle charger to your car in the process (I did!)
Once its done, (you can run the cycle more than once if you want full certainty), remove the funnel and replace the coolant reservoir cap ensuring that it is tightened to the point where the arrows are pointing directly at each other.



Clear the previous error codes with an ODBC2 tool.
Use ISTA, Protool or your equivalent method for cleaning all errors so that you can scan again after your test drive.
I setup a Realtime log of coolant temps and oil temps for my test drive.

Enjoy your hard work with a test drive
Take the Z4 out long enough to warm up the engine and see it hold temps. A few good pulls then to ensure nothing will surprise you later, when you need it to be reliable.

You're DONE! And this was a very engaged DIY. If you also replaced other parts along the way, you've saved yourself future headaches and done it at a much lower price that your local dealer or indy. Great Work!

If anyone finds an error, please let me know and I will address -- I'm certainly not an expert, I just used all of the methods available to research and organize the work for my own use.

[raymond.harper]

Very nice! Thank you for posting

[B21]

Excellent write up..

FWIW I got caught out on my 20i with one of the snap fit hoses to the thermostat / block…(can’t remember which)..point bring it looked like it had locked, survived for 3 days use thrn popped off and dumped all the coolant in short order..turns out it wasn’t fully seated..

[Christopher72]

FWIW I got caught out on my 20i with one of the snap fit hoses to the thermostat / block…

You're not alone. It happened to my friend, and he was stuck in a nearby neighborhood after his rad hose popped off of his BMW. He said the worst part wasn't that he lost the coolant and would have to reattach, but that he had to sit and wait in the toxic coolant spill in front of unhappy homeowners for 2 hours until his X5 could be picked up.

From that story, I was extra vigilant for each of those connections that they were all the way home and clipped.

[B21]

FWIW I got caught out on my 20i with one of the snap fit hoses to the thermostat / block…

You're not alone. It happened to my friend, and he was stuck in a nearby neighborhood after his rad hose popped off of his BMW. He said the worst part wasn't that he lost the coolant and would have to reattach, but that he had to sit and wait in the toxic coolant spill in front of unhappy homeowners for 2 hours until his X5 could be picked up.

From that story, I was extra vigilant for each of those connections that they were all the way home and clipped.

Paranoia just means you know what’s going to go wrong..

[mittu]

Damn. This is a lot of work. I need to change my water pump before it pops. On 93k miles.
E89 engine bay is bigger than e90, so initial thoughts were it'd be an easier job. Guess I'm wrong.
E90 how to videos are everywhere. Wish someone would make a a few decent ones for the e89. See if anyone's figured out any tips & tricks.

[B21]

Damn. This is a lot of work. I need to change my water pump before it pops. On 93k miles.
E89 engine bay is bigger than e90, so initial thoughts were it'd be an easier job. Guess I'm wrong.
E90 how to videos are everywhere. Wish someone would make a a few decent ones for the e89. See if anyone's figured out any tips & tricks.

No shortcuts on the E89..the write up was pretty much spot on..

[Christopher72]

The most important thing for this type of repair is to put a good water pump (OEM or BMW) in and, certainly, at 100k miles, replace your hoses and O-rings... While you're down there, make sure it counts...

[mittu]

Completely agree. A decent water pump is around £300. I think OEM is continental.
Generally speaking for a water pump it's pricey so it's tempting to buy a cheaper one for 100-150. From reading e90 posts, these cheaper pumps start failing after 20-30k miles.
It's not a job you want to do twice, or worse, pay to have it done twice.
100% stick to OEM brand or better.

[Hillboy38]

Thanks for posting this guide. I followed it as written and it is fantastic.