Author Topic: Coolant flush procedure  (Read 244 times)

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  • au Australia
Coolant flush procedure
« September 28, 2018, 17:21:24 »
Hi guys...would appreciate your advice.

I am going to drain the existing coolant in my FD diesel. I plan to do it like this:-
With engine cold..
*remove fill cap
*remove radiator drain plug and empty old coolant
*siphon out any old coolant in reservoir bottle

*replace radiator drain plug
*fill radiator and reservoir with distilled water and take for a spin. I plan to heat this water first to (hopefully) allow the thermostat to open quickly.
*Turn heater on the allow old coolant to disperse with new distilled water. Continue driving for 10 minutes or so.

I plan to repeat this procedure a few more times until coolant drains clear.

I am going to refill with Nulon One, which has a 10 year life.
:link: ONE 100% Concentrate Coolant - Nulon Products Australia
at a ratio of 50% with distilled water.

It specifies on the Nulon website not to mix this coolant with red, green or blue coolant, hence the repeated flushing that I plan to do.


Is there a better way?

Thanks guys..



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  • au Australia
    Ipswich
Re: Coolant flush procedure
« Reply #1 : September 28, 2018, 17:28:07 »
There's no drain plug in the block which is a nuisance, I have not done this but removing the thermostat would allow full flow and be able to reverse flush it, maybe remove lower hose from block. Will create some extra work and I'm not sure about the style of gaskets used either so you may need a new one.

I drained mine, filled with distilled, ranit then drained again, added the total amount of concentrate needed then topped with distilled. Not the most perfect way but I was using green with green. Wonder how the dealers do it if at all?
  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

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  • au Australia
    Ipswich
Re: Coolant flush procedure
« Reply #2 : September 28, 2018, 17:29:48 »
Oh, turning heater on won't do squat. these days thay're full flow and it's just the flap doors internal that redirect the air to produce hot air. In other words the coolant is always passing through the core.
  • 2008 i30 SLX CRDi Auto, 2010 i30CW SLX CRDi Auto. 2008 i30 CRDi SX manual, Welly

Re: Coolant flush procedure
« Reply #3 : September 28, 2018, 19:24:54 »
Thanks for that useful advice!

I changed the coolant in my Getz yesterday...and it has a drain plug that you need to undo with a phillips head screwdriver. It also has a radiator cap.

The i30 is different. I haven't noticed before but did when I dropped the old coolant just now. No radiator cap as such and a dedicated tap at the bottom of the radiator that is undone with fingers.

I just let the old coolant drain and have re-filled with demineralized water (through the coolant reservoir).
The old coolant was green. Nulon now have a green 7 year product
:link: Green Premium Long Life Coolant 100% Concentrate - Nulon Products Australia

Depending on how impatient I become draining and refilling in order to get the fluid to run clear, might settle for the 7 year one.

Is there any danger in this system in getting air blockages when refilling? Or is it just fill and cap-off?

Re: Coolant flush procedure
« Reply #4 : September 29, 2018, 03:13:44 »
Well...I persisted. :happydance:

Five fills and flushes with demineralized water later (with a drive to circulate in between each fill and drain) and the job is done to my satisfaction.

I was able to undo the drain plug safely just after a short spin (showing operating temperature 88C on the Scangauge)...so not having to wait for a cool-down was a bit of a timesaver.

Heating the water in a kettle and then putting into the coolant reservoir made it around 73C when I started each short spin. Another timesaver.

The coolant colour lightened with each flush, as you would expect. It ended up a pale yellow, which is similar to the colour of the Nulon One. I kind of admitted defeat after repeating the routine 5 times in all.

I think that I could have done the whole routine another 5 times and still not had clear water. That green dye that is used in radiator coolant (like a cockroach) is designed for the long haul.
« Last Edit: September 29, 2018, 03:32:24 by Paolo5 » »

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Re: Coolant flush procedure
« Reply #5 : September 29, 2018, 05:19:26 »
Good on you Paolo.  :goodjob:
  • MY18 PD SR & 2014 1.6 GDi Tourer (Prev had 2008  i30 CRDi & MY11 Petrol CW)

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  • au Australia
    Tasmania
Re: Coolant flush procedure
« Reply #6 : September 29, 2018, 08:18:05 »
Glad you got it sorted in the end.
For what it's worth this is the method that my mechanic bloke uses to change the coolant in my vehicles and it seems to work well.

He disconnects the hose from the thermostat housing to the top of the radiator header and connects as shown in the pic.
The top of the radiator is connected to a hose leading to a container of hot clean water (about 20-30 litres) sitting on top of the old oil drum.

The output from the thermostat has a hose going to a waste container.
When the motor is started and run until the thermostat opens hot water will be introduced into the system and the old coolant will be discharged out into the waste container.

The motor is run until only clean water is seen to be discharging from the thermostat hose and you know then that the old coolant has been flushed from the engine.

At this point the water container on top of the oil drum has the correct mix of new coolant and clean water added and the motor run until the new coolant discharges into the waste container.

The engine is stopped at this point and all the hoses are disconnected and the radiator to thermostat hose is reconnected.
The reserve tank is removed and emptied out and refilled with new fresh coolant.

All that remains to be done now is to bleed air from the system and the jobs done.




Apologies is this seems long winded and especially if this is a bit of old hat to old mechanics here, but it intrigues me every time I see him do to one of my cars so I thought it worthwhile passing it along here.

By the way, this is my Holden Rodeo being done earlier this year, used to do the Corolla the same way.
I assume it would work on the i30 as well, but the manual indicates it doesn't need flushing for 10 years anyway.
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