How to change Inverter & Radiator coolant IS300H

[IS300FSPORT]

Lexus recommends the following coolant/anti-freeze change:

- 100,000 - Radiator & 150,000 - Inverter 

Its well debated online to follow manufacturer recommendations v Reports of early water pump failures due to the coolant becoming acidic. Dont over think it if you want to do it just get on with it.

Mine is on 52k & 8 years old it was not due however if I leave it until it gets to 100k it would probably take 15-20 years before it is replaced i'm sure you will all agree anything more than 10 years is questionable. 

(Disclaimer - Do so at your own risk)

Tools required

10mm deep socket  & ratchet, Flat head screwdriver, Axle stand, funnel, Ramp, jack, chocks, 10L bucket, Gloves, Cardboard,

Lexuspartsdirect provide 7L of Pink Super long life coolant for the 100k service package. This was just right for both inverter & coolant. However if you run short you may run into trouble. Best practise to have 2x 5L bottles to hand. The remaining you can just use for top up as necessary in the future although its a sealed system there shouldn't be any leaks if your loosing coolant theres a problem!

Warm the car up, put heater temp to max, airflow (blower) on lowest. This will open the thermostat & drain the coolant from the heater Matrix assisting in getting most of the coolant out.

SAFETY FIRST

Drive the car onto  ramp, apply handbrake, chock rear wheels, if you want to lift the car higher jack it up & place axle stands.

Remove the plastic undertray held on by 10mm nuts & plastic push fit clips. 

Place your cardboard under the car now. You will see 2 drain valves dont remove them initially just loosen so it can start draining position the bucket right under the drain valve so you catch the coolant you can control the flow.

*It may be hot if you warmed the car up so be very careful*

- Yellow drain valve is the radiator coolant & white is the inverter.

One at a time doesn't matter which I chose to do the inverter first.

Approx 20 mins for full drain.

Remember to tighten both of the drain valves back up.

Now go to the top remove the inverter coolant cap using your funnel slowly pour coolant until it is above the F marker. You want to slightly overfill the reservoir to start with so it doesnt run the inverter pump dry as soon  as you try to start the car it will bleed the air and gulp the excess coolant.

>>>>> Do not mix the caps <<<<

Next remove the cap for the radiator reservoir & top up to the Full mark. Now remove the radiator cap &  Place the funnel there & fill coolant slowly until it pours out you will see bubbles coming out. You can help squeeze out any air locks by squeezing the rubber hose. Providing both reservoirs are full & there is coolant in the radiator you now want to bleed air out of the system to prevent overheating.

Leave the caps off the inverter & radiator.

Go to the car > foot on  brake> press start within 3-4 seconds BEFORE the engine starts turn it off. Do this 2-3x. This will run the inverter pump sucking in the coolant. If the level drops below F top it up again to the Full mark. Thats inverter pretty much bled & done. Put the cap back on.

You need to put the car into maintenance mode before starting the car so the engine remains running to warm up & bleed any air locks. Otherwise it switches to EV cutting the engine out not allowing it to warm up or do the bleed procedure.

As soon as you start the car keep eye on the temp gauge. It should not exceed the normal operating range which is in the middle. What you want to do is let the car warm up & for the cooling fans to come in twice to ensure there are no air locks. The funnel may release bubbles which is normal bleeding air out & the coolant may try to come out of the funnel. Volcano effect its normal  as it gets hot. 

Turn the car off, exiting maintenance mode. Now  restart as normal & go for a drive & top up as necessary over next 2-3 cooling cycles it may need a slight top up.

I appreciate this is a DIY guide & may not be the perfect method & may well have missed a step on here, but should it help anybody then thats great.. I have since done over 100 miles no issues. 

Upon observation I think the inverter coolant could easily go on another 50k the coolant was clear, however the engine coolant although not contaminated appeared cloudy so well worth doing I dont think it would have done the engine any favours for another 10 years. I probably wont touch it for another 5 years. Not a difficult job can be messy thats the only downside.

Dispose of the coolant at a recycle centre & job done. 

 

[matt8]

Thanks! Excellent tutorial. Something I hoped to do on my own in the near future.

[Notamech]

Awesome write up. Quick question... Do you know roughly how much coolant is required if you drain and refill only the radiator and not the inverter. I just got my waterpump done and looks like they charged me for only 5l and seems like some was left over and they decided to overfill  the radiator reservoir quite a bit (way above the B mark)  like coolant was pouring out of the overflow spout when i got home so had to manually pump it out to set the correct level later when the car was cold. So sounds like even 5 litres is too much? 

[IS300FSPORT]

1 hour ago, Notamech said:

Awesome write up. Quick question... Do you know roughly how much coolant is required if you drain and refill only the radiator and not the inverter. I just got my waterpump done and looks like they charged me for only 5l and seems like some was left over and they decided to overfill  the radiator reservoir quite a bit (way above the B mark)  like coolant was pouring out of the overflow spout when i got home so had to manually pump it out to set the correct level later when the car was cold. So sounds like even 5 litres is too much? 

 

5L would comfortably cover the radiator/engine drain.

The inverter took 2L.

When they remove the water pump most of the coolant from the engine block will have drained as well. It depends if they decided to drain the radiator down in which case it would be a full drain down. 

Dont check the reservoir when its hot I have noticed the level sits just below the B mark when hot as the coolant expands, when cold its slightly above the F mark where it should be. They probably overfilled it to prevent a customer from returning. For Toyota/Lexus models its probably safer to 'slightly overfill' than underfill. You will notice on the reservoir there is a black rubber tube that will automatically drain the coolant away into the engine bay if the reservoir reaches its maximum capacity  after a couple of heat cycles it will settle down. See pic.

In your case it sounds like it was way overfilled its best to suction a little bit out to release some pressure. 

Also out of interest what age & mileage was your waterpump replaced at? & what tell tale signs are there it needs replacing?

[Notamech]

42 minutes ago, IS300FSPORT said:

5L would comfortably cover the radiator/engine drain.

The inverter took 2L.

When they remove the water pump most of the coolant from the engine block will have drained as well. It depends if they decided to drain the radiator down in which case it would be a full drain down. 

Dont check the reservoir when its hot I have noticed the level sits just below the B mark when hot as the coolant expands, when cold its slightly above the F mark where it should be. They probably overfilled it to prevent a customer from returning. For Toyota/Lexus models its probably safer to 'slightly overfill' than underfill. You will notice on the reservoir there is a black rubber tube that will automatically drain the coolant away into the engine bay if the reservoir reaches its maximum capacity  after a couple of heat cycles it will settle down. See pic.

In your case it sounds like it was way overfilled its best to suction a little bit out to release some pressure. 

Also out of interest what age & mileage was your waterpump replaced at? & what tell tale signs are there it needs replacing?

Yes familiar with the overflow tube and thats where it was spewing excess coolant from. When i checked when hot the bottle was nearly full not just upto the B mark and when the car cooled down I used a suction pump and removed nearly a quarter litre of coolant so as to ensure theres no more mess. I like keeping the engine bay clean.  It now sits at the B mark when cold and goes slightly above that when hot.

 

My car is at around 91k and the pump didn't totally fail, i wasn't loosing too much coolant but there was a pink crust around the water pump and after driving there would be white powder everywhere in the engine bay from a few drops getting flung by the belt and that drying up into white powder. Also it appeared that the pump was failing at the bearings and that means I run the risk of bearings seizing on say a long drive. It appears that others have also seen similar failure (at the bearings) and it sounds like it could be due to the design than the coolant going bad i.e the crankshaft pulley directly driving the pump pulley with no tensioner in between. I know lexus made changes to the belt at some point but dont think there ever was a recall in the UK or if this newer belt is any better at preventing failure.

[IS300FSPORT]

45 minutes ago, Notamech said:

My car is at around 91k and the pump didn't totally fail, i wasn't loosing too much coolant but there was a pink crust around the water pump and after driving there would be white powder everywhere in the engine bay from a few drops getting flung by the belt and that drying up into white powder. Also it appeared that the pump was failing at the bearings and that means I run the risk of bearings seizing on say a long drive. 

Thanks it's interesting I have replaced the belt & coolant now more as preventaive maintenance, I am hoping to get at least 100k before the water pump needs replacing. 

To be fair 90k is reasonable service life, its not a diifficult job as the engine is mounted sideways it seems accessible to do a DIY job. 

Will report back...