I noticed on my sister and brother-in-law's 2007 Prius there is a fan belt. I noticed on our 2010 Prius there is no fan belt, or at least one that I can not see. Is the Prius 2010 the only vehicle manufactured without any fan belt? alfon
The fan belt is located in the same place as the belt for the water pump...it's history. The only belts on a G3 are on the seats and in the tires, if my information is correct. I'm still something of a noob to this car, but I think I'm on pretty solid ground here. Someone will very quickly correct me if I'm wrong. EDIT: The Prius isn't the only car out there sans fan belt, many newer cars have electric fans that are bolted to a shroud behind or atop the radiator. My low-tech pickemup truck is one of these, but it does have a serpintine belt---that powers a number of items. The Prius is belt-free. If my memory serves, it is one of a very few vehicles that has an (OEM) electric water pump.
The Gen III Prius has an electric motor powered water pump. So, there is no drive belt on the pasenger end of the Prius Engine. A fan belt drives a fan (and usually an alternator) in cars with the engine oriented in line with the car. Most cars have not had fan belts since most cars are front wheel drive with laterally orietented engines. There are drive belts on most cars however, to turn the engine coolant pump, alternator, power steering hydraulic pump, air conditioning coolant compressor. The 2nd Gen Prius did away with the power steering and air conditioning coolant compressor as both of these auxialiaries were made electric motor driven. No Prius has an alternator, as the the 12 V is powered off a voltage converter that runs off the traction battery (very similar to a PC power supply). The traction battery is charged by MG1 and MG2 through the Hybrid power train action. So, that left only the water pump in the Gen II. Now in the Gen III that is gone too.
The performance car community has known about using electric, water pump motors for a long, long time. I don't know about other production cars but it is a change that has been a long time coming! FYI, I'm already working out how to do the same with my NWH11. <grins> Bob Wilson
Let me just add that the beauty of the electrically driven A/C and water pump is the ICE need not be running to cool the engine and/or the cabin. In stop and go traffic, both are kept comfortably cool while the ICE is quiet, saving gasoline by not running. The Prius is a remarkable machine, and has many well thought out features. It would be remarkable even if it did not deliver fantastic fuel efficiency, which it does. I find my 2010 quiet, comfortable, and efficient ..... I have driven it across the country twice this year; both very pleasurable experiences.
That, along with the flywheel, helps to smooth the engine's power pulses. The four-cylinder engine only has two power pulses per 360 degrees of crankshaft rotation. BTW the Highlander Hybrid V6 engine also does not have a serpentine drive belt, but the engine water pump is mechanical and powered by the camshaft timing belt.
