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Discussion Starter #1
Hey everybody,

I'm going to do a complete coolant replacement. I have found plenty of information regarding replacing the engine coolant. But I haven't found much for the power control unit. If you don't know, there is a separate coolant system for the power supply of the hybrid system. I'm seeing a lot of replace at 100K or 5 year recommendations. Well I have a 2012 CT 200H F sport. So I figure I am due. I've read the coolant becomes corrosive and eventually eats away the interior of your radiator, heating core, etc. I know there is a petcock valve that allows the coolant to be drained easily for the engine coolant. I just can't find anything on the power control unit. I haven't lifted the car up yet to take a peek but I was wondering if anyone else has replaced this themselves? Can it even be flushed? does it even have its own water pump? I plan on flushing the system with distilled water and then filling back up with fresh antifreeze. I do know how much fluid it takes however.

Any quick tips that would save me some time that you all have found out would be tremendously appreciated.

Also, what is your antifreeze of choice? I like Amsoil for other fluids but haven't done much research on their antifreeze.

Thank you,

Seth

Power Control UnitInitial fill 2.2 quarts
With Recirculator SystemInitial fill 7.3 quarts
With O Recirculator SystemInitial fill 6.9 quarts
 

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Well I went ahead and went with Amsoil Ethylene Glycol 50/50 Pre-Mix Formulation. https://www.amsoil.com/shop/by-product/other-products/antifreeze/passenger-car-and-light-truck-antifreeze-and-coolant/?code=ANTPC1G-EA
They have great products and I have build a bit of brand loyalty with them. I also went with the Dominator Coolant Boost. https://www.amsoil.com/shop/by-product/other-products/antifreeze/dominator-coolant-boost/?code=RDCBCN-EA .

I haven't done the flush yet but I intend on giving updates just in case I can help someone else. The coolant boost sounds pretty nice. It is supposed to heat your engine up faster in the cold and cool it down quicker when it is hot. They boast 40% quicker heat up to where your thermostat starts allowing hot air through your vents. I also plan on installing some sort of block heater or oil pan heater. I will start a separate thread for that however.

I'm not the only one who has had their 2012 model make oil starvation noises when it is cold. I plan on going to have the "cold soak" fix done if it is still in warranty. Hopefully this will aid in keeping the engine happy with me in the absolute coldest of weather.
 

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Well I have completed to coolant flush. I decided not to try to mess with the power control unit. I read a couple posts online mentioning it would require some specialized computer equipment from the dealer. I'll save that for them. But I did find the engine coolant flush to be entirely easy. If I were to do it again it would be much faster. I had started taking off panels under the engine to get to the petcock. When actually you can get to the petcock valve with your hand without removing any panels at all. (MAKE SURE YOUR CAR IS COLD BEFORE YOU START OR YOU WILL BURN THE EVER LIVING CRAP OUT OF YOURSELF, ALSO USE JACK STANDS). I highly recommend getting a small rubber hose or something to connect to the end of the petcock for the drain. This will make it much easier and save yourself a huge mess. There is a little oval cut out under the front end of the car that you can reach your hand through to turn the valve. It is inches from the drain. I have smaller hands but it was very easy for me. Now since it is a pressurized system you have to unscrew the coolant reservoir cap before it will really drain. I left the cap to just rest on the reservoir to prevent from dust getting in there. After I started draining I left it drain for several hours to make sure everything was out. I made sure to go ahead and lower the car to make sure the drain was at the lowest point. After nothing was dripping anymore I jacked it back up and closed off the petcock valve. I then refilled the reservoir with distilled water. Do not use tap water! I kept filling until the water level was at the full line and it was holding the level there. I turned the car on and put the heat on the hottest setting. I waited until it started blowing hot air in the cabin and then started a timer for 5 minutes. Once the 5 minutes was up I turned the car off and let it sit several hours. I didn't want to burn myself. When I came back out I repeated the drain sequence. I then made sure the petcock valve was closed. and SLOWLY started pouring the amsoil antifreeze back into the reservoir. I used a funnel to keep from making a mess. Now the thing that sucks about their antifreeze is that it isn't colored. So it is hard to see the level on the side of the reservoir. I made sure I didn't see anything dripping under the car. I lowered the car and kept filling until It was holding steady at full. I've read the system is self burping. But just in case I made sure to massage the coolant lines with my hand to get any extra bubbles out. I locked the cap back on and started the car. I haven't had any trouble and it is running fine. I haven't added the "dominator" coolant boost yet. I was going to keep checking the level and run it for a couple of days first.

Now again, I did this because it is recommended to change your coolant every 5 years or 100k miles. When I went to a dealership they acted like I didn't need to mess with it until 100k miles. That was a red flag for me. It seems like they just want to do oil changes and up sell me tires I don't need. It is also nice to take a gander at your under carriage every once in a while to see if any other repairs may be needed. Check for leaks, rust etc.
 

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Nice write up. I also have a 2012 but only about 55k on it. Will have to find time to do the change. The color still looks nice and pink.
 

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Once you look under the hood of the CT200h you will notice that it is the same as the 3rd Generation Prius making the Coolant change the same. The original Post is a great write up but I'm a visual guy myself. Hope this helps...

 

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And if you are considering the Inverter Coolant...

 
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