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Coolant Flush

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  • Coolant Flush


    To ensure the Paj is ready for summer, though low 30's are common already up here in Gladstone, I've been reading the procedure to flush the coolant in the NL GLX 3.5V6 and have a question: The procedure talks about the engine drain plug for the coolant. Where can I find this?

    Also, for those who have done this, do people ever experience air locks after flushing the system? I replaced heater hoses on a falcon a couple of years ago and had a air lock when using the heater that would take about 20min to clear every time I wanted the heater.

    Any hints to prevent a air lock would be helpful.


    2012 NW with some fruit

  • #2
    My procedure is as follows and works both on the 3ltr and 3.5ltr(actually works on all cars). Forget the drain plug.

    Start with a cold engine:
    1- Remove hoses from radiator(don't have to disconnect them from engine)
    2- with garden hose on medium-high, flush the rad out and also the overflow bottle. Fill overflow to the high mark when refitting it back in.
    3- remove a heater hose from firewall and stick the garden hose in the end of it and let it go until water comes out fresh, then put garden hose in the open heater port on firewall and repeat, also do the bottom rad hose.
    4- reconnect everything back up
    5- add rad flush to the radiator and then top up with water
    6- start engine and allow to warm up with rad cap off, once it's at temp and the top of the rad is getting hot, put the rad cap back on and go for a good 20min drive.
    *7- Let car sit for at least an hour with bonnet open in the shade before repeating steps 1-4, but this time remove thermostat and also flush down the top hose as well. For an even more thorough flush, fill with fresh water and repeat 1-5 but don't use rad flush this time.
    8- when you buy the new coolant check the shops guide and find the capacity of the system(both 3ltr and 3.5ltr is 9.5ltr), buy enough concentrate to treat that amount.
    9- Fit new thermostat when reconnecting everything back up
    10- Add enough coolant concentrate to treat 9.5ltrs in the rad first, then top up with fresh water then repeat step 6. Make sure you fill overflow to high mark and allow engine to warm up with rad cap off.

    * When flushing a warm engine, regardless of the method used, you need to atleast allow an hour or two before flushing!!
    Also, turn the garden hose onto a trickle/dribble and let it slowly cool the engine right down before blasting through with the med-high. Failure to do let the engine cool down can result in head damage if cold water is blasted through.

    **Replace rad cap and thermostat when doing a coolant change.
    **Drain plug on block itself will not remove everything from the engine. You can pull them out and do the above flush as well if you wish to, although, it is not needed with this flush technique.
    **Do not just fill up with pre mix after a flush, use concentrate as stated above.

    Hopefully this helps
    97' NK 3ltr GLX LWB Manual | 3" lift | Wildcat headers | K&N air filter | 2.8 crawl gears | 4Terrain clutch | 2.25" exhaust | Factory locker rear | TJM 10,000lb winch | TJM snorkel
    97' NL GLS LWB Auto | 6G75 3.8ltr | Redback Headers


    • #3
      Thanks a lot mate. I'm sure it will help. Just gotta get around to it now.
      2012 NW with some fruit


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