What else should be replaced when replacing the water pump?

My impression is that coolant pump failures at such low mileage are rare, assuming it hasn't been coping with overheated coolant.

When the pumps have to be replaced, people often replace the coolant thermostat at the same time, because it's easy then. However, I've yet to hear of an original thermostat actually failing at any mileage.

 

I still don't understand why Gen3 owners have been so passive about engine destroying ability of this valve failure via class action lawsuits? Head gasket failure due to a stuck valve boosting engine temperature is a smoking gun... Guess its not common enough for outrage of significance?

 

Which valve? Maybe pre-edit?



^ got this alert too, Priuschat snafu?

 

I got confused when reading this first time around and thought OP was mentioning a different valve, rather than just the EGR valve itself. Once I realized it, I edited you and Chapman out of me asking for help, but notification was already sent.

Point being this is the first thread I've seen that specifically said valve was jammed and forcing engine temperature higher. As in cause and effect, which is much less vague than how others have presented EGR issues in the past.

 

Looks like maybe you mixed up this thread with the other recent one where the exhaust heat recirculation system was being discussed. That system has the little wax-thermostat actuator down on the exhaust pipe that waggles an exhaust valve, controlling whether the exhaust goes straight through the pipe, or has to go through the EHRS heat exchanger and heat up the coolant. If the valve gets stuck in the latter position, it heats up the coolant more than intended.

In that other thread, rjparker posted graphs of the two temperature sensor readings, one at the engine water outlet, and one at the coolant return from the EHRS exchanger. The graphs show that your signal of the sticking valve is likely to be a temperature-warning light because of the EHRS temperature reading, while the engine temperature reading stays relatively tame. So you get notification of the EHRS issue and, ideally, go unstick it. I'm not sure how much excitement should be attached.

 

Perfect example of the LLM problem solved via a select all for reply... As in it lacks critical oversight / quality control. For example, there's no Serpentine belt in a Gen3 Prius. There's also only one or two things on that list that are relevant... Or as my personal AI was explaining to me earlier this evening:

"AI reaches for rhetorical scaffolding the way a nervous speaker reaches for filler words. Brevity is harder because it requires knowing what to omit, which requires genuine judgment about what the reader already knows and what actually needs saying. AI tends to over-explain because it can't fully model that gap." --Claude

 

Actually it addresses none of the most common failure paths.

Head gasket failure - design flaw
Excessive Oil Burning - design flaw
Inverter failure - design flaw
Brake Booster Assembly -design flaw
Hybrid battery - expected around 150k or higher

Each was repaired free if they failed within certain timeframes and mileages.

Improved parts include head gasket, pistons, rings, inverter power electronics and perhaps brake booster since repeat problems on the last item is rare.

Sure you should do regular maintenance on fluids and spark plugs. Generally fluids twice as frequently as the maintenance schedule recommends. Plugs are ok as recommended around 100k. I believe oil and coolant are key. If its not burning any observable oil in 5k miles you want to keep it that way. Change the brake fluid every 50k.

I have never changed my water pump in 350k miles. But I do have a temperature display with an early audible alarm.

P10 display $35


Change the fluids. Save for a new hybrid battery.

 

I’d add periodic, in-depth brake inspection, and brake fluid replacement.

 

Aisin OEM thermostat. I'm not an original Toyota parts only zealot, but I've recently been burned by a name brand aftermarket thermostat and going to the OEM fixed it.

 

The best thing to do is not use aftermarket parts in the cooling system, coils, hybrid batteries, egr valves or for sensors including the maf.

Part of the aftermarket problem is poor quality. Another is straight out counterfeits advertising as oem using oem counterfeit boxes and part numbers.

Example:
New NGK coil costs owner thousands

Watch through end where spark plug takes out a 40k mile engine

About 95% of the time the original parts your car already has are better than the aftermarket or counterfeits. Which makes "preemptive" changes a crapshoot and waste of money.

Quite a few times we hear how no problem or one problem turned into two or more issues after multiple parts were changed.

Diagnosing a real problem first is the way to go.

Changing fluids and spark plugs makes the best sense on a hybrid with no issues.

 

I agree. IF your prius is burning no oil, then leave the EGR alone. Leave the intake manifold alone. Change all the fluids meticulously and put the best oil money can buy in every 10k mile or 5k if you feel like it. (my 2011 and 2014 Prius got Mobil 1, and have never burned oil (n=2, statistically irrelevant as most success/failure claims are, on the internet)

The coolant temp gauge is an interesting option -- not likely to cause a failure, and way cheaper than a new water pump........

Oh, one more suggestion that will not extend your Prius life, but DOES need to be done to save money -- grease the brake pad slider pins. The grease gets old before the pads wear out, and when the sliders stop working, you will ruin what's left of you pads and rotors......

 

If you're going to replace anything, maybe get rid of the thought that a parts cannon fired at a top-ten list of problem areas is going to reset the clock and give you a bunch of carefree miles.

An old Prius demands vigilance. Keep your powder dry (wallet closed!) and stay ready for the next hit.