Hello everyone! This summer I’ve done a long trip with my family and our Prius+. Is same as V but Europe version. Engine is the same. And I’ve experience something I never did: engine overheat (red icon in dashboard). It never happened to me before and I will tell you the background. Car was fully loaded with luggage. 6 persons on board, 2 adults and 4 kids. Also on the roof I have a travel box (or however is called) mounted and there also luggage. As you can tell the car was heavy. Could not make it heavier I guess. Acceleration was poor, as you can tell. And it’s ok. It should be. Prius is not a powerful car. All was fine and dandy until I got to the highway. Slowly got to 130km/h and enabled cruise control. As you know on cruise control Prius goes hard on the pedal to reach the speed setting and let’s go of it there. But if you put together heavy car, with an incline on highway and cruise control flooring it I got an overheat sign. I don know if this is to be expected or my water pump under stres conditions is giving out. Result: cooling liquid got out of the reservoir and shot out. I was left with a very little quantity of liquid in it. A 1L got out. I was able to continue the journey without issues after refilling the reservoir and no more cruise control so that the car will not put the engine on full throttle. As long as i was not pushing the car to max everything was ok. So I’m asking you is this normal behavior? You should not stres the Prius to the limit on very heavy conditions? Today got to work normally, car empty, I even red lined it, no problem, nothing.
And one more thing: no error codes received. Just that red overheat icon in the dashboard when reving to high and engine got overheated. After let go of the throttle it went off.
It would help to know what year your vehicle is and what the outside temperature was at the time. How many miles and does it burn oil? Was the ac on? Overloading the car and running 130 kmh (81 mph) is asking for trouble on this engine. I set an audible alarm at 78 mph and try to drive less than 72 mph. As you noted, the standard cruise is only appropriate on level or slight down slopes. However overheating is not the issue - blowing a head gasket is more likely. Overheating won't normally throw a code. The Prius +/v has a very robust engine cooling system and should not have overheated the engine even in your situation. It certainly should not of over pressurized the reservoir and released one liter of coolant. I would get an obd2 scanner or dedicated monitor with a lower audible alarm and watch it carefully. Normal is 195f even at 130 kmh (81 mph) increasing to 205f under severe ambient and load. The warning light comes on at 248f. P10 monitor $35 alarming at 78 mph and 210f. Water pumps do fail as do head gaskets. If it has an early head gasket leak it can slowly burn coolant drops per day until it is low enough to overheat. Normally a hg will cause occasional severe rattling for 5-20 seconds at cold start.
