Gen 2 vs. Gen 3- Water Pump Disaster, more expensive repairs?

Below are some pics of a water pump off of a 2010 Prius with 140 k miles on it:



This is a magnet driven pump (Electric field drives the pump). Through disassembly, what I found to be the failure point is the impeller as the top side separated rather easily when a small force to remove the impeller from the housing was applied.

Based on this and having a 2010 Prius II with ~154 k on the clock and going strong, I will replace mine at 200 k miles as preventive maintenance .

Thanks again to @m.wynn for allowing me to disassemble and takes pics of his old water pump

 

Don't feel the need for preventive replacement at 155k miles? In theory the new one should get you to 300k.

I think I would replace mine at 150k or sooner. Just because I don't see myself keeping my prius beyond 250k. I wouldn't benefit beyond that

SM-N900P ?

 

While the plastic impeller seems a bit flimsy, one could replace it sooner. If you wanted to team it with an engine coolant change at 150 k miles, that would make sense.

But I am passed that and will not have the coolant out until 200 k. Only reason I will wait until then. I also don't believe this will lead to eminent failure prior to 200 k miles.

I work with mag drive pumps and they are a great technology. When I hit 200 k miles, that should be in late 2019 , early 2020. This would be 10 or 11 years on the pump. So for that reason, I would retire the current and replace with new.

 

Yes makes sense to do it with coolant. That's my rule for my gen2 cars lol

SM-N900P ?

 

Smart man. I just hate draining, saving and putting it back in if I don't have too.

When 200 k miles hits, it will be a major service and our Prius will be sitting in the garage for several days .

Here's the 200 k miles list that seems to keep growing:

• Engine coolant
• Inverter coolant
• Trans fluid drain and fill
• Engine water pump
• Intake manifold cleaning
• Egr valve and cooler swap
• Spark plugs
• Oil change

Items on the fence that might get added:

• Inverter water pump (it will have been in 11 years in service at that point)
• Brake fluid flush (might get done prior to this)
• Brake pin lube (would be ~3 years since last round)

Open to other suggestions too.

 

Any thoughts on replacing a Gen2 water pump with a Gen3 version? Or maybe a Prius C version?

 

The gen2 and gen3 engines are completely different so it's unlikely you can just swap water pumps willy-nilly. The Prius c and gen 2 share the same 1NZ-FXE and the water pumps may be the same, though I'm not sure than the engine in a Prius c has actually received any updates that would make it any better.

 

I believe the c did swap the pulley on the water pump for an electric motor. The c pump would probably fit on an earlier 1NZ, but how would you control it? I think it's variable-speed, CAN-controlled.

-Chap

 

Can't you join it back and get it working again?

 

2011 Prius 110k miles. Just replaced water pump and thermostat as preventive maintenance. Read the following Prius Taxi fleet post where 80% failed without warning and damaged the engine so they just put it on 100k mi replacement schedule.

Water Pump | PriusChat

Also did water pump on a previously owned gen 2. Can share some observational differences and operation and failure modes.

Gen2 is simple mechanical belt driven pump. Failure modes are leaks from the shaft and eventual noise from shaft wear against the bearings. Belt always pulls on the pump shaft in one direction probably leading to its eventual wear. Anyhow, warnings are pretty obvious, either early coolant leak seeping on the shaft, or on the ground or noisy water pump.

Gen3 is electric of course and failure modes seems to be just electric motor stop spinning. After the install, hooked up techstream and took it for a couple of drives and observed the following

- Pump spin seems to track engine on/off. 0 RPM when ICE off, about 2500-3500 RPM when ICE on. My techstream kept crashing but this was the observed behavior. Pump never ran while ICE off or vise versa. Engine temps generally cooled a few degrees when shutdown with water pump off so seems like there is no need to run the pump independent of ICE.

- Temp tracks around 185-190+F. Typical thermostat open/close temps.

- Techsteam shows a target RPM and actual RPM (mine was always 400-500 higher than target) This would suggest Pump has a built-in speed sensor.

So a couple of interesting questions and analysis

- If pump has a working internal speed sensor, ECU should know if its not spinning at speed. Curious why ECU doesn't put up a warning in most cases. Of course ECU won't know any impeller deterioration without more complex observations.

- Going to electric didn't get independent operation from ICE. Probably just 1) efficiency 2) eliminate entire accessory belt system.

Anyhow, just some info. Perhaps worthy preventive maintenance if Prius Taxi guys see high no warning failures.

 

There's more information on how the pump speed is controlled and measured in this post and following.

I was mistaken above in #28 where I thought the pump was CAN-controlled. The ECM just sends it a pulse train where the duty cycle (% of time at the higher voltage) indicates the requested speed. The pump produces a square-wave tachometer signal at two cycles per pump revolution.



Before Gen 3, there was a separate electric pump for moving the coolant through the cabin heater when the engine was off. With the electric water pump, they were able to get rid of that extra one; the engine pump does continue to run when the engine's stopped, if needed for heat.

I've also observed it continuing to run with the engine stopped, if the coolant temperature is high.

And of course, by being variable speed, instead of locked by a belt into always the same proportion to the engine RPM, it can save energy even when running, if it doesn't have to run very hard.

 

Ah thanks for the details. Make sense cabin heat need a pump independent of ICE and gen3 offers a merged solution. Also note on running pump with engine stopped with high temps.