Inverter Fluid Color or Change to Yellow no longer orange

[FusionNAZ]

I have a 2014 Ford Fusion Energi and the coolant in the reservoir for the inverter is turning or looks yellow. The regular coolant for the engine is still a nice orange color. The car has 92,000 miles and it runs great but just am concerned that its a different color for the inverter. Also, I have looked high and low and do not really see a diy on how to change the inverter fluid. I know that there are tons of Prius guides and this is really important to keeping the hybrid electrical system healthy. Any thoughts on this would be appreciated.

[zippoking]

I did a partial drain and fill of a gallon after 50k miles, and it drained from that reservoir too. I think the color change isn't a huge concern, but you're due for coolant change now I think.

[FusionNAZ]

I did a partial drain and fill of a gallon after 50k miles, and it drained from that reservoir too. I think the color change isn't a huge concern, but you're due for coolant change now I think.

Sounds good did you undo the plug underneath the car? I am assuming its kinda like the prius in design.

[zippoking]

There a drain underneath the front shield, not the same one as the eng oil, but its a real pain in the butt to get to, I had to also loosen a bracket that goes across just under the radiator, but if you have a hose to put on to drain then its not too bad.

Edited February 22, 2019 at 02:42 PM by zippoking

[16vjohn]

My car has 131k and it looked a little yellow to me as well. It's probably fine and will likely do its job for years to come, until well after it's useful life is over. That said, I will lose sleep over this, so it must be corrected. Here's how I did it.

 

There is no drain for the inverter coolant loop. I looked up and down and even through my friend's AllData subscription. There's no drain for the inverter. I imagine there's a special flush tool that you connect to the upper hoses coming out of the inverter and pass distilled water until it's clean. If you pull the lower cover and remove the radiator support, you have relatively easy access to the lower hose clamp for the inverter heat exchanger. Note, when you pull the radiator support, the radiator, AC condensor, transmission cooler, and inverter cooler will drop down a bit. Lower it slowly, it'll fall about 1 or 2 inches. The louver mechanism is in the way, but you can push it back a bit. Might even be easier to shove something between the louver plastic and coolers to keep them separate... (a rolled up towel perhaps?). As you can see, the louver housing in mine is damaged from a minor fender bender, but you should still have plenty of access if you're patient. Last note, when you go to bolt the radiator support back up, make sure to remove the upper radiator support widgets. Reinstall them when the lower portion is bolted back up.

 

Further note, I was able to flush the system clean using only about 3/4 gallon of distilled water, pouring it in the inverter reservoir. I then used compressed air to blow the water out of the lower portions (very messy, make sure to have some towels ready). Refill took just over a quart of Motorcraft Orange 50/50. When you turn the car on (engine not running), the electric pump cycles on and off and self-bleeds. You'll hear air bubbles in the pump, makes it noisy. Be standing by to top off the reservoir as the pump cycles itself.

 

Lastly, if you're going to go through all this effort, you might as well drain the engine radiator as well. The petcock is easily accessible with the radiator support off. Drain and fill in AllData says just over 2 gallons, but mine was only about 1.25. Hard to say where the other .75 gallons went. There was air in the heater core, and I blew out the radiator with a compressor. I think you can pretty well do both cooling loops with 1 gallon of un-diluted Motorcraft Orange.

 

Cheers.

[zippoking]

I took a simpler approach, especially since I (think) I did it very early at around 60k miles.  Drain as much as possible from the petcock on the bottom of radiator, then refill and run a few times to top off.  But then I did all that again a few months later, and figure I've easily replaced about 75%.  It will always provide cooling, but the anti corrosion properties diminish over time, I've read.

[CaliGiant]

My inverter coolant looks like a weird color too. Its a lot light than the engine coolant. Maybe thats because the electrical coolant hardly gets hot compared to the NA engine coolant. I thought it was all on the same system though but anyways.

 

I tried to replace my fluid a couple months ago as it's getting to be that time but I had trouble getting the petcock to unplug. It was stiff as heck. I couldn't do it by hand but was barely able to turn it with pliers so I folded a paper towel and prayed it didn't break. It turned exactly 1/4 turn and stopped where it seemed it should but nothing. It tried turning it a but more,  pulling it out, working it back and forth a bit and still nothing. I didn't feel like taking off the hose because there are two pretty expensive systems to worry about and don't want to damage something by getting air trapped in there. 

 

Has anybody had trouble or a solution in dealing with the petcocks?

 

John, you said that the system automatically burps itself. Did the AllData say that? If that's the case i think I might just try to drain it through the bottom hose but I'm just hesitant on doing things that I'm not sure about. 

 

I learned the hard way in the early 2000s when I changed the coolant on my new Chrysler 300m and didn't realize there was a bleeder valve. I ended up overheating once every year or two, changing thermostats and eventually punctured the head gasket. I still got almost 200k on that car but looking back i realize that is why I kept over heating once a year or two. Eventually on a hot August day it gave up totally but I learned my lesson.