Not sure if this should be in the Prius C forum, Gen II Care & Maintenance, or Gen II Mods, but here goes... The Prius C and the 2nd gen both use the same engine (1NZ-FXE). The Prius C has an all-electric water pump for the engine; the 2nd Gen Prius does not. How viable would it be to replace the belt-driven pump on a 2nd Gen Prius with the electric pump from a Prius C? Any ideas how the pump itself is controlled - automatically by its own temperature, or by some computer somewhere else? Does it just take a 12V DC power line, or does it require a 3-phase drive for its motor? And would it be worth making this change?
I would discourage the substitution of an electric engine coolant pump for the existing mechanical pump. That is the type of change that may appear elegant but will likely cause more trouble in the end (consider the Prius inverter coolant pump as an example of a less-than-reliable electric pump.) Consider how a mechanical pump will typically fail: the pump shaft bearing starts to leak fluid. If you are merely a semi-aware owner (in other words, you at least manage to have your engine oil/filter changed at proper intervals), you will eventually discover this, either by seeing pink coolant stains on your garage floor, or noticing that the engine coolant level in the radiator reservoir is declining. This failure mode typically is not catastrophic as plenty of warning is being given. Another way that a mechanical pump will fail is if the serpentine drive belt decides to break. This would be a catastrophic failure, hence I suggest that owners periodically replace that belt, no later than at 100K mile intervals. Now compare to the electric pump. If this decides to fail, it will do so very quietly. One day the pump motor is running great. The next day the motor stops running. The only warning you will have is when the engine high temperature warning light turns on, and this compells you to immediately park on the side of the road and seek help. That is a catastrophic failure analogous to a broken serpentine drive belt. Nevertheless if you decide to implement that change, I believe you will find that the motor is DC. You'll need to locate the equivalent of the New Car Features manual for the Prius C to determine whether the motor speed is driven via pulse-width-modulation or some other means, and how the engine ECU decides when to activate the pump. It is likely that the existing engine coolant temp sensor is the means for the engine ECU to determine cylinder head temp.
Warning duly noted. It's a geek thing. (And I pride myself on being semi-aware!) This is the kind of information I'd need. I don't know, but I'd bet one of two things happens: 1) If Toyota did it right, they'll have a feedback loop consisting of the coolant temperature sensor, the engine computer, the pulse width modulator, and the electric pump motor. This allows them to get the maximum efficiency benefit. It also allows them to remove the thermostat from the engine, and control the temperature using the pump speed. (This would make it much more challenging to make the change). 2) If Toyota didn't do it right, the pump spins whenever the system is "READY" or whenever the engine is burning fuel. (This would make it simple to implement). Maybe I'll just buy the pump for $25k or so, and get a free car to go along with it.
This is on my list of things to try on the '04, but unfortunately the part is not available yet. It might be a few more months.
This is something I looked into when the gen3 came out, and enquired about here on PC, but will now start looking again. Implementation of the control of the pump should not be to difficult and speed control could even be done with one of the many control units already built and available for pennies. Motor rotation could be monitored and a super bright red lead used for a warning of non rotation.
I thought about it too when the Gen 3 came out, but when the C came out (with the same engine as Gen 2) it became considerably more practical!
Blue Sky thought. How about a more bold move. Put the C electric pump in and remove the thermos bottle pump... Keep the C pump running after shutdown to circulate hot fluid to the thermos. Then shut down. You could be down to three ( possibly two) water pumps.
As I see it there must be some efficiency benefit or why would Toyota implement the change with all the costs involved. I imagine the control would be much the same as in the gen3. I'll have to start digging. Another thought is adding the heat recovery system off the C
If you decide that you want to proceed with this project let me know. I have a C and can take pictures of its water pump for you. But, I have to locate it first in the engine compartment! It could be a remotely located pump for all I know but I think it is bolted to the engine because I have seen a picture of the pump somewhere...
Oldwolf a picture would be much appreciated, I would think it will be in the original mechanical pump position.Who was it said a picture is worth a thousand words?
As far as I can tell the water pump is somewhere above or in the vicinity of the oil filter. I will be changing the oil soon so getting the pictures will have to wait until then. Sorry.
I'm not sure if you are having water pump issues but, I changed ours at 120k and it was not very difficult at all. It was infinitely easier that the water pump on my Tundra.
No water pump issues at all. Changed water pump at ~100k as preventative maintenance - things wear out, and it's FAR cheaper to change it when I have the time to do it myself without taking time off of work. And you're right - replacing the pump was pretty easy (and getting the air out of the coolant once that was replaced wasn't bad at all). It's just that the geek in me likes the idea of putting an all electric pump on the '07 Prius (with the same engine as the new Prius with an electric pump.) The Scotsman in me recoils at spending $535 to do so though!
