Mg1 motor temperature number one overheating 360° f

I think the inverter coolant also cools the transmission in this generation of Prius. Check the inverter reservoir to make sure it has the proper amount of radiator fluid, and look to see if it's circulating. Cooking the motor is really bad for it. If windings are shorted then that will also generate heat.

 

No. But if it stays overheated for very long, they will be. If the windings were shorted, it would throw a code and you'd get the dreaded red triangle. A general rule of thumb with electric motors is that every ten degrees above the max temperature you run it cuts its life in half. As mentioned, check the inverter coolant first. Also check the transaxle fluid. If the inverter coolant is OK, I'd drain, examine (send for testing?) and replace the transaxle fluid. MG1 is smaller than MG 2, so it will change temperature more quickly. Plus it's the one that charges the battery, so it working harder in your situation.

I think I've only ever done this a couple times but I seem to remember the same behavior. That was in a Gen 2. Others more experienced can correct me if I'm wrong.

 

Then I think I'd either be checking the transaxle fluid or just take it to a Toyota dealer or a hybrid specialist.

 

How do we know if 360 degrees is outside it's normal operating range. I would think the hybrid system would set a trouble code if something is overheating. My 24 watt soldering iron tip is about 650 degrees. Might depend on what part of the motor the temperature is taken.

 

I have a 2010 Prius, 104,000 miles. When I do the battery life expectancy test with Dr Prius, the test requires charging the battery by flooring the engine. I experience what you are talking about except that the engine stops completely and Dr Prius says to take my foot off the pedal, then floor again. It takes 4 or five cycles to charge the battery.

I've wondered whether this is normal or a sign of a problem but there are no codes or other issues. My Prius runs perfectly in regular use.

 

In general, it‘s better to rely on the power management control ECU’s self-monitoring and self-diagnostic programming, rather than on ad hoc tests such as this, for which Toyota simply hasn’t disclosed the thresholds and other information needed to make a reliable judgment about whether a failure exists.

If the car wasn’t used for a while, so the HV battery might have a low state of charge, just leave the car in READY, with the parking brake set and the transaxle in P⃣, for 30 minutes, so the engine can run as needed to recharge the battery. For new vehicles in inventory, Toyota tells dealers to do this at least once every 60 days.

I’d expect a “Generator Temperature Sensor” diagnostic trouble code (DTC), such as P0A37-260, P0A3A-258, or P0A39-259, to be stored, if the MG1 temperature were outside the expected range for long enough to matter. Similarly, if there were a shorted winding in MG1, I’d expect a “Generator Inverter Performance” (P0A78) or “Hybrid Generator Performance” (P0A92) series DTC to be stored.

If you’re referring to the “Mtr-Temp (MG2) Max” value in the Data List, the Repair Manual (more info) for 2010 doesn’t mention a time period, but in the 2013 and later editions, Toyota adds the words “after power switch turned on (IG) in current trip.” I imagine this applies to all third-generation models.

 

I think you're right. Someone put in the wrong fluid. And with the glitter coming out, putting in the right stuff probably won't fix it now.

 

You could try filling it with the correct Toyota WS fluid and replacing it again after a short while.
If it's already damaged beyond repair it won't harm anything more.

 

I've never seen MG1 and MG2 temps vary more then 30 degrees. With all the other system temps reading "normal" with one outlier I'd be looking at the sensor providing bad data which is causing a cascade of problems. Sensor or wiring issue that is messing with the signal is where I'd start.

 

So, what came out of the transaxle was anything but Toyota ATF WS, plus it was full of metal flakes. That fruit is so low hanging that you have to bend down and pick it from the ground. I'm with @meeder; get the low hanging (aka easy) fruit first. Put in the Toyota ATF WS, run it a few miles, and see if the problem persists. There's a good chance that it will because metal flakes are not supposed to come out in the transmission fluid. If the problem goes away, drain and fill again and pray that the thing will hold up for a while.

 

It still looked ATFish. It's not what we typically see coming out of a Prius either color wise or "glittery". People seem to forget that there are still an awful lot of gears in that transmission moving around that can make metal like that. Granted, none of that is good.

I'd be shocked if a splash lube style lubricant caused temp spikes like that. It doesn't transmit any power in the Prius so blaming improper fluid on that doesn't make a lot of sense. The only way it could possibly contribute is if the chemistry started "eating" materials inside there.

 

Yup! That's what I'd suspect given the symptoms.