DIY - Coolant Reservoir Replacement

[BzsBimmer]

Background - My 2015 M3 had coolant residue around the seams of the coolant reservoir/tank and I was starting to notice a loss of coolant after some short time.

I have an extended warranty on the vehicle but I also opted for the higher deductible knowing that I work on my car a majority of the time, and would only use the warranty for major items.

Figuring I’d tackle this myself while I was in the engine bay for some other maintenance and upgrades, I was also concerned with the amount of coolant loss I’d incur in the engine bay, lifting the car, getting a catch can, making a mess, etc.

Luckily, I found a way to do this with little to no coolant loss or mess in the engine bay!

Ok... on with the DIY

WARNING - DO THIS WITH A COLD ENGINE. SERIOUS INJURY CAN OCCUR IF OPENING COOLANT WHILE HOT!!!

Difficulty: 3/10

Time: 1-2 hours depending on familiarity of car and mechanics. If first time working on car, set aside more time.

Coolant Reservoir PN: 17132284600 (already comes with the cap so no need to order that separately)

Things Needed

• Small flat screwdriver
• 10mm socket
• 6mm socket
• Ratchet/electric driver
• BMW coolant
• Distilled water
• Shop towels

Optional

• Favorite cold beverage
• Gloves
• Coolant mixing container
• Used coolant disposal container
• Flashlight
• Torque wrench

Open hood - If you can't figure this step out... please head to your repair shop to handle this job.

Prerequisite - Remove strut bar according to this DIY first - https://f80.bimmerpost.com/forums/sh....php?t=1014235

Step 1 - Using 6mm socket, loosen clamp around drivers side intake pipe.

Step 2 - Disconnect hose from retainers along intake tube.

Step 3 - Disconnect intake tube from plastic retainer that hold to brace.


Step 4 - Disconnect intake sensor and swing cable out of the way.

Step 5 - Once intake is separated and free of connections, pull up on intake box and entire intake will pop from retainer grommets and come free. Set aside.

Step 6 - Locate top hose to reservoir. Using small tipped screwdriver, gently lift metal clip up and then gently pry hose away. Put a piece of paper towel in the reservoir hole to keep coolant from pouring out later.


Step 7 - Put top coolant hose between other hoses to keep it elevated and out of the way.


Step 8 - Using the 10mm socket, remove the bolt securing the tank to the bracket. Loosen the 10mm bolt that secures the bracket to the strut mount. No need to fully remove that bolt.


Step 9 - Lift the reservoir up to release it from its retaining grommet. Turn the reservoir so the bottom coolant line is exposed along with the sensor wire and so that you won't spill coolant (tilt sideways).

Pull the hose clip like you did in step 6 and carefully disconnect the coolant hose. QUICKLY lift the hose as high as you can lift it and tuck it under the hose pictured in picture 2. This will prevent coolant from spilling out everywhere.
Pic 1 -
Pic 2 -

Step 10 - Using small screwdriver, place it inside rectangular opening and GENTLY apply pressure/leverage to release retention feature. Disconnect sensor.


Step 11 - Lift tank out and set aside to drain or catch fluid. DO NOT let coolant drain into street or leave open sitting out. Pets are attracted to it and can get sick/die. Dispose of used coolant responsibly or catch it and reuse it.


Step 12 - Reinstall coolant tank. Keep the hose as high as you can while installing it into the reservoir. This is to keep coolant from spilling.
Note that the lower coolant hose is keyed to only go in one way. While the two keys look identical, one is slightly thicker than the other so it will not lock into place if installed 180 degrees incorrectly. Push the metal clip back into place to lock in the hose and tug firmly on the hose to ensure it’s locked.


Step 13 - Reinstall the electrical connector and metal bracket to the tank. Torque to 10Nm.

Step 14 - Reinstall the upper coolant line to the reservoir. Push metal clip back into place and give it a firm tug to ensure it’s locked.

Step 15 - Mix distilled water and BMW coolant 50/50 ratio unless using premixed. I won’t get into debate on BMW coolant vs other brands. You do you boo boo.

Step 16 - Open reservoir cap and fill coolant to at least the bottom of the yellow fill line. You may need to add more after bleed cycles.


Step 17 - Run bleed procedure as follows:

1. Connect battery charger.
2. Switch the ignition on.
3. Switch on low-beam headlight.
4. Set heater to maximum temperature and turn blower down to lowest speed.
5. FES (driving experience switch) must not be in ECO PRO!
6. Press accelerator pedal for 10 seconds to floor. Engine must not be started.
7. The bleeding procedure was started by pressing the accelerator pedal and takes approx. 11 mins. (the electric coolant pump was activated and switches off automatically after approx. 11 mins.).
8. Then adjust fluid level in the coolant expansion tank to maximum.
9. Check cooling system on watertightness.
10. If venting has to be carried out again (e.g. if cooling system is leaking), allow DME to fall completely (leave ignition key removed for approx. 3 mins.), then repeat from Point 2.

More here LINK

Step 18 - Reinstall intake and intake sensor connection.

Step 19 - Reinstall strut bar per DIY - https://f80.bimmerpost.com/forums/sh....php?t=1014235

Hopefully this was easy enough and save you a trip to the dealer, or indy.
Enjoy

[jason.404]

Ive read that the main coolant system is belt driven so you need to turn on the car to do the bleeding procedure. Is this so? I was not able to bleed my system after my replacement.

[BzsBimmer]

Originally Posted by jason.404

Ive read that the main coolant system is belt driven so you need to turn on the car to do the bleeding procedure. Is this so? I was not able to bleed my system after my replacement.

Electric water pump
Take the cap off the expansion tank and you should see fluid coming from the overflow tube if done right.

[jason.404]

Originally Posted by BzsBimmer

Electric water pump
Take the cap off the expansion tank and you should see fluid coming from the overflow tube if done right.

Probably a dumb question but where is the overflow tube located. Also, after you have pressed down the gas pedal for 10 secs, should you hear the pump start working noticeably or should there be a delay before you start hearing the pump?

[BzsBimmer]

Originally Posted by jason.404

Probably a dumb question but where is the overflow tube located. Also, after you have pressed down the gas pedal for 10 secs, should you hear the pump start working noticeably or should there be a delay before you start hearing the pump?

Picture of said tube is right above step 7.
There will be a slight delay. Make sure you follow all the steps with the heater settings etc.

With the cap off you will start seeing fluid flow out regardless if air/no air in system because of the pump running.

[jason.404]

I followed the procedure and heard the water pump working for the 11 minutes. I did not see any bubbling or coolant flowing in the expansion tank. Although i did hear the top mount intercooler tank making sounds, is this normal?

[BzsBimmer]

Originally Posted by jason.404

I followed the procedure and heard the water pump working for the 11 minutes. I did not see any bubbling or coolant flowing in the expansion tank. Although i did hear the top mount intercooler tank making sounds, is this normal?

Wellll...
I can say that this worked on my sons 335 when we did his meaning we saw coolant coming from tube. My car is torn apart at the moment due to installing comfort access retrofit so can’t go through the process. Hoping someone else can verify that coolant should be flowing out of the tube.

When I did mine, I didn’t have the cap open to see coolant but could hear the pump running. If you heard the pump running, I’d say success. I’d run it again to be sure to evacuate as much air.

[jason.404]

Originally Posted by BzsBimmer

Wellll...
I can say that this worked on my sons 335 when we did his meaning we saw coolant coming from tube. My car is torn apart at the moment due to installing comfort access retrofit so can’t go through the process. Hoping someone else can verify that coolant should be flowing out of the tube.

When I did mine, I didn’t have the cap open to see coolant but could hear the pump running. If you heard the pump running, I’d say success. I’d run it again to be sure to evacuate as much air.

I see. I actually found a youtube video here on the forums where the member explains the s55 cooling systems. Theres the charge cooler system and the engine cooling system. The charge cooler follows your bleeding procedure and the engine cooling system side follows the steps bellow:

1. Remove expansion tank cap (helps you verify "burping")

2. Start the car with the highest heat setting at the lowest intensity and low beams

3. Monitor the expansion tank for burping for around 5-10 min


Skip to min 31:32

Here is the link to the video

Hope this helps.

[TopJimmy]

Originally Posted by jason.404

I've read that the main coolant system is belt driven so you need to turn on the car to do the bleeding procedure. Is this so? I was not able to bleed my system after my replacement.

Jason,

You are correct. The pump purge procedure (heater on, pedal push) cycles only the cold-side circuit to bleed the smaller TMIC mounted reservoir.

The hot-side circuit and large reservoir requires a top-up-and-drive procedure. With engine cold check the large reservoir and make sure it's full, then cap it properly and go drive easily just until the car is warmed up to working temperature. Now go park and let the car sit until completely cooled (overnight preferred). Check the reservoir again cold. If coolant is below the low mark top up and you must do the drive/heatup/cooldown process again before any hard driving. If coolant is between low and full you can top up and then drive as you like. Check again next morning.

Factory fill-up procedures use a vacuum filler, but that's not needed for basic user maintenance. If I drained my whole circuit I would just do the extra effort to fill up really good and make sure I purge any bubbles out.

-Jimmy