N52 Water Pump and Thermostat replacement

Reamesy

Reamesy

Senior member
 Whitchurch
Site Supporter
So my car is a 2011 serviced every 7K with 44k just.

I thought I would carry out preventative maintenance and change the pump and thermostat. £320 from AutoDoc. Pierburg pump and Mahle thermostat.

All in took four hours. Made easier by removing the,
Air intake cowling 4 x 8mm screws
Expansion tank 2 x 10 bolts. Top and bottom hose and coolant sensor from the bottom.
Drop the anti roll bar which gives about two extra inches af clearance (it’s still tight).

The hardest bit was the top bolt on the pump. The bottom two are easy. Don’t mistake the AC pump bolt for the top bolt. It’s out of sight but can be got with patience.

Lube all the connections with silicone spray and ensure the spring clips are fully up. Make sure they but right up and then insert the C clip to its lower position. Give it a good tug as you do not want this popping off. One big, one small.

Button everything up but leave the under tray off so you can check for leaks. Top up with BMW coolant 50/50 deionised water Run the bleed procedure.

Remove the expansion cap.

Ignition on but not started. Plug the seat belt in so the car does not sleep. Fan on lowest setting with temperature turned up fully. Depress the accelerator for 10 seconds. You should hear the pump fire up. It takes a good 10 minutes to complete.

I ran it twice and ensured it was topped up to the correct level during.

Then took it for a run. All good 👍 but never want to do it again for a good while.

Next auxiliary belt. AUTODOC belts are 1830mm but genuine belts are 1827mm. 🤔 I might just bite the bullet and by genuine as I did save on the pump. Does anyone do the alternator clutch pulley?
 
As stated very very important to make sure the C clips are really really seated..otherwise they can pop off 10 miles later! :tumbleweed: :rofl:

Must do mine soon!
 
As it’s my daily and I travel to the Cotswolds every week just don’t want to risk it on age alone. Better prevent than regret on the motorway 🧐
 
Reamesy said:
Top up with BMW coolant 50/50 deionised water Run the bleed procedure.
Click to expand...

I used distilled water for the Official BMW 50/50 coolant because BMW recommends it.

If you experiment with other forms of water purification (outside of what BMW recommends), the most crucial part is using water close to a neutral pH (7). Pure distilled water has a pH of 7 and degrades slightly as it is open to the air. DI and RODI water are slightly more acidic (lower pH between 5 and 7). I'm not aware of the impact of the BMW concentrate on the pH, but YMMV.
 
Christopher72 said:
Reamesy said:
Top up with BMW coolant 50/50 deionised water Run the bleed procedure.
Click to expand...

I used distilled water for the Official BMW 50/50 coolant because BMW recommends it.

If you experiment with other forms of water purification (outside of what BMW recommends), the most crucial part is using water close to a neutral pH (7). Pure distilled water has a pH of 7 and degrades slightly as it is open to the air. DI and RODI water are slightly more acidic (lower pH between 5 and 7). I'm not aware of the impact of the BMW concentrate on the pH, but YMMV.
Click to expand...
I meant distilled. 5L from Halfords £4.79
 
Reamesy said:
Christopher72 said:
Reamesy said:
Top up with BMW coolant 50/50 deionised water Run the bleed procedure.
Click to expand...

I used distilled water for the Official BMW 50/50 coolant because BMW recommends it.

If you experiment with other forms of water purification (outside of what BMW recommends), the most crucial part is using water close to a neutral pH (7). Pure distilled water has a pH of 7 and degrades slightly as it is open to the air. DI and RODI water are slightly more acidic (lower pH between 5 and 7). I'm not aware of the impact of the BMW concentrate on the pH, but YMMV.
Click to expand...
I meant distilled. 5L from Halfords £4.79
Click to expand...

actually most 'distilled water' sold in uk is de-ionised..much cheaper process..distilled water is only used in pharma and food..

BMW's concern was the degree of hardness not the relative ph ..

In fact if the water was soft enough as measured by the 'degrees' then it is permitted to be used in the 50/50 mix...

Not a lot of people know that..

My first year at Uni doing chemistry did have some benefits!
 
That's good to know. I pay attention to pH because I have a FOWLR tank that needs to be topped weekly. I've heard not to put RODI water into computer cooling loops without buffering, or it will impact the metal fittings.

My chemistry knowledge is from YouTube and not Uni -- Which explains quite a few mistakes... :lol:
 
Christopher72 said:
That's good to know. I pay attention to pH because I have a FOWLR tank that needs to be topped weekly. I've heard not to put RODI water into computer cooling loops without buffering, or it will impact the metal fittings.

My chemistry knowledge is from YouTube and not Uni -- Which explains quite a few mistakes... :lol:
Click to expand...

Corrosion chemistry in engines is complex so you are forgiven my child! :rofl: :rofl: :rofl: :rofl:
 
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