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All Star
1,384 Posts
Discussion Starter · #1 ·
Hi there!

Decided to renew my coolant.

Got two bottles of G12.

The first question is, how should I mix it, as it is concentrated.

Should I go for the 1:1 mixing?Also, should I mix it with de-ionised or pure water?

And finally how much coolant mix needed to fill up the full system?

Also do you recommend to flush out the system, before filling up with g12?

And as I can see, we dont have DIY for the coolant change...

DIY index

Is there anything to pay attention when I'm doing it?

Found something:

  1. When the engine has cooled down, remove the Vw coolant tank cap.
  2. Draining the Vw coolant from the 4cyl cooling system:
    Remove the
    lower radiator drain plug from the lower front of the radiator (Vw A4,
    Vw Passat). Remove the passenger side lower radiator hose. Remove the
    outer Vw coolant hose that connects to the oil cooler. To drain the
    heater core you'll need to remove the hose on the coolant flange or
    transfer pipe located on the back side of the engine. This hose goes
    from the cylinder head to the heater core.
  3. After the system is done draining, put the Vw coolant tank cap back
    on. Carefully work off and remove the smallest hose that is connected to
    the top of the Vw coolant tank. Be careful, the tank nipple likes to
    crack and break off.
  4. With a blow gun and compressed air on low, carefully insert the blow
    nozzle into the small hose. Wearing safety goggles, carefully force the
    air out so that any Vw coolant that's still trapped in the cooling
    system is released.
  5. Reinstall the Vw coolant drain plug. Reinstall the coolant tank
    hose(s). Fill the Vw cooling system with distilled water. Start the car
    and air bleed the cooling system as outlined in the factory Bentley manual. Run the car until the cooling fan comes on.
  6. Repeat steps 1 through 5 until the water comes out clean.
  7. Verify that you have the correct anti-phospate anti-amine G11 or G12
    Vw coolant. If it's full concentrate, mix a 50/50 ratio per the Bentley manual.
    Fill your Vw cooling system with this 50/50 mixture. Note: Some factory
    Vw coolants sold by dealers are already premixed and do not require
    further delusion.
  8. Run the 4cyl engine and check for any Vw coolant leaks.
  9. Top off the coolant tank to the fill line. Do not overfill.
  10. Using a permanent marker, write 'G11 or G12 Coolant Only' on the Vw coolant tank.
  11. Be environmentally responsible and dispose of your old Vw coolant properly.

Livin' by the sword
5,180 Posts
What mix to use depends how cold it gets where you are. 1 - 1 would give you a little scope for topping up with water in an emergency without weakening the solution too much.

Use Clean Tap Water according to VW data sheets. Also, the volume of coolant required is variable dependant on model specifications. Data sheet states that 3.0ltrs coolant with 3ltrs water will protect to -35, so that would indicate 6ltrs maybe? Also a note to say not to increase concentration ratio past 60% coolant - 40% water.

All Star
1,384 Posts
Discussion Starter · #3 ·
Thanks Rusty!

One thing I cannot find out..

Where is the breather hole / screw?

Livin' by the sword
5,180 Posts
There's no breather hole or vent. The system is self bleeding. See below

- Fill with coolant up to max. mark on expansion
- Fit expansion tank cap.
- Run engine until radiator fan cuts in.
- Check coolant level and top-up if necessary. When the engine is at normal
operating temperature, the coolant level must be at the max. mark; when the
engine is cold, the coolant level must be between the min. and max. marks.
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