Classic Prius Coolant Replacement

When you say "TLLC" I assume you mean Toyota Long Life Coolant. I didn't know that Carquest sold that. What was the price?

The Classic engine coolant change is much easier than 2G because Classic does not have the coolant heat recovery system. Just open the radiator and engine block drains to drain the coolant. Close the two drains and refill with coolant amounting to 50% of system capacity, and the remainder using distilled water. Fill the overflow container using a 50%/50% mix.

Rev up the engine with the cabin heater temp set to MAX HEAT so that you can get air out of the coolant passages and the heater core. Continue until you do not hear air circulating in the heater core and the coolant level in the radiator does not drop. Make sure the radiator and the overflow container are both full.

Keep an eye on the coolant level for the next few days and replenish as needed until the level no longer drops down when the engine is cold.

No need to flush unless you see lots of rust and debris in the old coolant. In that case, flush with distilled water.

It is much harder to get air out of the Classic inverter coolant loop, compared to 2G, even though Classic has 2 bleed valves. Plan to spend much of an afternoon working on that.

 

Hmm, I think that ~$20 is the going price, but I haven't bought Toyota LLC for a few years (use Toyota SLLC instead.)

The instructions are:

Make the car IG-ON and listen to the inverter coolant pump so that you can hear what it should sound like when there's no air in the system. Also look at the inverter coolant reservoir and note the step in the fluid level (where the fluid at the front is higher than at the back of the reservoir) as well as the turbulence in the fluid. All of this shows you that the pump is circulating fluid properly.

Then make the car IG-OFF. Find the coolant drain plug which is at the bottom of the transaxle, closest to the engine. This requires a 24 mm or 15/16" socket to remove. Do not confuse with the transaxle ATF drain plug which is closer to the driver's side of the car.

After the fluid has drained, replace the plug using a new aluminum washer and tighten to 29 ft.-lb.

Fill the inverter coolant reservoir with your coolant/distilled water mixture. Loosen the two bleed valves. Attach vinyl hose leading from the valves to the opening in the coolant reservoir.

Make the car IG-ON. Listen to the pump running. Note how it sounds like there's air in the system. Open the bleed valves. Refill the reservoir with coolant/water mix. Close the bleed valves. Make the car IG-OFF. Refill the reservoir.

Repeat this around 20x or more, until you don't hear air bubbling in the system and you see the fluid turbulence in the reservoir. Then fill the reservoir to the MAX line, remove the vinyl hoses, tighten the bleed valves, replace the reservoir cap, and you are done.

If you find that the bleed process is not yielding results, it may help for you to take a short drive, around the block, then resume the bleed process. Do not drive very far while the inverter coolant loop has air within, as you may overheat and destroy the inverter.

 

No for Classic; yes for 2G. The 2G radiator has a bleed valve on top, to help in getting air out of the radiator.

 

Toyota part number 90430-18008

$1.51 MSRP; they are priced at $1.13 at toyotaworld.com
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While we are talking about gaskets, the oil drain plug gasket part number is
90430-12031

 

It is unnecessary; drain and refill is all that is required.

 

As a mere mortal, if you wish to spend $1,345 and have access to a Windows laptop, then you too can acquire a close equivalent to the Toyota diagnostic laptop:
https://techinfo.toyota.com/techInf...hinfo/html/prelogin/docs/tsliteflyertinfo.pdf

I wouldn't bother with a pressure tester unless you believe that your engine coolant system has a leak. The way that you would know this is if you note that the engine coolant level has dropped significantly over time; or if you see evidence of a coolant leak such as whitish or pinkish stains on the radiator, hoses, coolant pump, etc.

 

I suggest that you use a squeeze bulb to remove any excess coolant, especially from the inverter coolant reservoir.

50K miles is the correct interval when using SLLC. IMO there is no need to flush if you don't see debris in the drained coolant.

Regarding your question about why a "qualified technician" is required, you've provided one answer in your question below.

You may recall that I earlier explained that the Classic inverter coolant bleed process is very difficult. Try the repair manual procedure that you cited, try driving the car around the block. Just keep working at it until you do not hear air in the system and you can see fluid turbulence in the reservoir. Good luck.