Changing Coolant.

[bradp51]

I have two Aurions. I changed the coolant in one about 6 months ago using the method as seen on the youtube by the Car Care Nut.  I just did it again on the second Aurion.  This time instead of just emptying the radiator on the bottom tap I also attached tubes to the metal pipes on the engine block plugs.  You have to jack the car up to get to these.  The front one is behind the dipstick tube and the rear one is easy to see and get to.  The front one I moved the heatshield for the manifold, but did not take the 02 sensor out.  The front one is difficult to get to. The surprising thing to me was that I got nearly 5 litres of coolant out of the rear block tap.  I carefully measured it all into buckets and got more than 7 litres out of the system.  This included about 300ml out of the overfill plastic tank.

The car care guy goes thru a great video of purging the system which works great.  I read in my Haynes manual for the car about the two engine block taps.  Haynes also suggests removing the thermostat and flushing water thru with a garden hose via the radiator hose.  I did not do that but I did put 2 x bottles or radiator flush in and drove for half an hour then came back let it cool and then jacked it up and emptied all that fluid.  I then filled it up with brand new toyota genuine fluid from the dealer which was cheap.  Then went thru the air bleeding which works exactly like he says it does.  I purchased the container with the special radiator caps from amazon as he links to his video. Works well.  I changed the oil at the same time and filter.  I do oil changes now at 7500 km and use Mobil 1 full synthetic.  I managed to buy some in bulk recently on special and use it in the other Aurion and another car which takes the same oil grade.

Just thought I would  share my experience about using the engine block taps.  You use a 10mm spanner to undo them and there is about a 25mm long 8mm spigot or pipe that you attach a hose to which i fed into a container under the car.  It is a bit time consuming but I think worth it if you want to fully change the fluid out of the  whole system not just a portion of it.

[Tony Prodigy]

That was kind of you to post up Brad. Thanks for the tips.

I am planning to do mine pretty soon and as always, like to take photos and post up a nice little DIY for others to see for themselves and hopefully take something from it.

You did good to get that much coolant from the block. It's important to get as much of the old stuff out as possible and even try to flush more out where possible.

The system takes around 9lt if I'm correct, so you got pretty close. I would always recommend to drain the block and try to flush more out. For the flushing process, I've purchased a stash of demineralized water for the flushing as opposed to using the garden hose. I wouldn't flush with tap water. It's too contaminated in my opinion, not to mention the minerals you end up introducing into the engine. 

I've been meaning to get under it and investigate those drain bungs before I attempt the work. This is my pre planning stage so I can be ready to go on any given day.
Have all the necessary tools, apparatus, fluids and prior knowledge ready so there's no issues.

 

[ZZT86]

How timely, I did this exact same procedure the other day when it was hot here in Melbourne, which made bleeding quicker.

I too also accessed the block taps but couldn't see the front one & just ignored it as I got most from the rad tap (4.75L) & then the balance (2.5L) from the rear block tap. I connected a hose to both before opening the tap for extra cleanliness.

Not flushing using tap water makes sense (on a newish car at least) as the water isn't pure like the premixed stuff in the Toyota SLLC bottle of which I purchased 2 (10L) for about $70 from my local dealer.

If tap water is used then some is likely to remain in the system & eventually degrade the overall quality of the coolant & potentially cause premature seal & bearing failure, something we're all trying to avoid in a cramped 3.5L V6 FWD setup. Some would call it overkill, I'm just taking extra precautions.

Some additional notes I made:

1: open bleeder 1 - 1.25 turns max otherwise air may get in

2: bleeder hose not immersed into overflow coolant funnel otherwise will suck back in

3: install cable tie to base of bleeder hose to prevent leak & falling off

4: make sure funnel rad-cap tight fit otherwise will leak (had to tighten mine)

5: bleed process took 13minutes in 30+degree heat in garage before steady flow from bleeder hose

6: let engine idle a further 15minutes for coolant flow to normalise & little to no air/bubbles from overflow funnel

7: next time use both block taps to drain

8: fill coolant to crease on funnel plenty otherwise risk overflow during bleeding process & engine running @ 2500rpm

After turning engine off I extracted excess coolant from funnel, removed the funnel & bleeder cap from radiator neck, filled to top then closed her off with factory cap. Filled cars overflow bottle to full & let the engine cool overnight. In morning when cold refilled overflow bottle to full as engine cool down process will suck some back in, lightly washed engine bay of coolant & dirt & dried it before starting. I checked the coolant level was full after a few drive cycles to make sure it was all perfect, car runs beaut 🙂

A painless process all made possible due to the great AMD aka the Car Care Nut, our greatful & dedicated friend from the Toyota world 🙂

 

Edited February 3, 2023 by ZZT86
credit to AMD

[Tony Prodigy]

Nice one Rick. All this talk about changing coolant is getting me psyched up to do mine 😄

On 2/3/2023 at 9:04 PM, ZZT86 said:

I too also accessed the block taps but couldn't see the front one & just ignored it as I got most from the rad tap (4.75L) & then the balance (2.5L) from the rear block tap. I connected a hose to both before opening the tap for extra cleanliness.

I had a quick look online and this is the picture I found for the front drain point. (SEE BELOW).
I haven't physically looked at mine yet, but according to the picture, it appears to be next to the oil cooler flange adjacent to the dip stick tube.

I wonder how much more coolant one can recover if both are drained instead of just the rear which you did. I also wonder if the heater core also drains back whilst utilizing the rear drain. I would assume approximately 500mm or so in the heater core.

The coolant capacity is 9.4lt. You were able to extract 7.5lt leaving 2.15lt, so I would be inclined to drain the front section of the engine too, to get as much out as possible.
Flushing can be another option, but here's what can happen. 

1. Those who foolishly use the garden hose to flush will introduce contamination and will inevitable leave behind a few litres of mineralised water, which will degrade and contaminate the coolant.

2. Flushing with demineralised water is preferable, but will also leave a quantity of water inside which will then dilute the already 50/50 mix thus reducing it's overall effectiveness.

So, in my mind, I would wait and see how much I can collect from radiator, front and rear drain bolts and see if it's even worth flushing.
If one decides to replace the thermostat, then you could pour demineralised water into thermostat hole and allow to drain the block this way and the same for the radiator too. 
The heater core is the only thing that concerns me. I guess you could force the coolant out with compressed air. Just need to access the heater hoses, if that's easy enough.
It would be interesting to see how close to 9.4lt one can get doing all this.

You make some good points too Rick. Namely these:

On 2/3/2023 at 9:04 PM, ZZT86 said:

1: open bleeder 1 - 1.25 turns max otherwise air may get in

2: bleeder hose not immersed into overflow coolant funnel otherwise will suck back in

3: install cable tie to base of bleeder hose to prevent leak & falling off

I'll do a bit more research before doing mine. I had to recently buy two 5lt coolant from Toyota because I have no idea where the other two are. I also have on hand, a full set of Genuine Toyota Parts, cooling system hoses, thermostat, gaskets, water pump (new Improved Toyota Item with petal design flange) and Radiator for any incidental issues that may arise.
I might just do the coolant change this time and decide later at which point to do a full cooling system overhaul. At that point, I'll just swap out all those parts I have stored and see it through another 10 years or so. The car is running great at 150+K and mostly original. The only things I've had to replace on the engine during my ownership thus far was the upstream O2 sensor. That's it apart from routine maintenance. 

 

 

Edited February 4, 2023 by Tony Prodigy