Electrically Burned two water pumps

Sounds like a problem we had in the past but we ended up fixing a coolant line that was installed incorrectly.

Can you take a pic of the engine coolant reservoir tank line leading to the block?

 

You can follow in this thread how you can watch how the water pump motor is being controlled in Gen 3.

It might be worthwhile to compare the signals in a Gen 4 (ideally a known-working Gen 4 with a known-working Gen 4 pump). That might add to what we know about any difference between the pump generations.

Watching the signals in this Gen 3 where the pumps are failing might then turn up an explanation.

It looks like this when the car is asking for 50% (which is what you get if you select 'ON' in the Techstream active test). The top trace is what the ECM sends to the pump; the bottom is the pump tachometer signal back to the ECM (around 3300 rpm in this pic).



In this one, I'm not using the Techstream test, but the cabin heat is turned on. You can see the ECM is asking for about 40%, and the pump is doing about 2730 rpm.

 

You got that picture yet?

 

That's from an oscilloscope with backprobes on the WPI and WPO circuits. Details are in that thread I linked.

In my experience, the ECM doesn't ask for that much unless the engine coolant temperature is getting pretty high. In the experiments I was doing with the fans unplugged and running the engine temp up extra high, I would see pump speed requests in that range.

I am wondering more and more whether there is some circulation obstruction in your engine or hoses, and the engine is getting extra hot, the ECM is responding by calling for more and more pump, and the pump isn't getting much cooling because of the poor circulation.

Sounds like kind of a suicide mission for a pump.

 

With this many damaged pumps so quickly you need to measure the voltage going into the pump, as well as measure how much volume the pump is pumping per minute. Suspect one of these two is the source of the problem.

 

See post #2.

 

The first time I saw #2 this totally whizzed by me, but looking again I think it's a trick question.

Full points for none-of-the-above, there are two reservoir lines, one goes to the near-side top of the radiator, the other goes to the little Y fitting and splits to the far-side top of the radiator and to the nipple on the top of the outlet pipe from the cylinder head.



If it's the Gen 4 head, instead of the little nipple on that outlet pipe, there's a little one on the top of that outlet fitting, 16331.



Or does that 16331 fitting attach to the block in Gen 4, rather than to the head? (Hard to see on the parts diagrams.) Edit: found it, cylinder head. Easier to see on the EGR diagram, 25-01.

 

Ok, so the hose in the foreground right here is attaching, I trust, to the burp nipple on your 16331 fitting (only the fitting you have includes the gray electric doohickey)? I can't see it, so that's where it's going, right?

And the tee in the left foreground goes to the throttle body, because the Gen 4 cylinder head doesn't have a nipple for it?

And this foreground hose still has its original Y fitting clipped to the front of the engine bay, going to the lower reservoir nipple and the far side radiator top nipple?

And the other throttle body hose I can see going to the side nipple on the descending tube from the EGR cooler, which looks right.

And I can't see where the main hose on that descending tube is going, but I presume it's going to the bypass nipple on the thermostat housing, right?

 

Well, it turns out to be the 16331-37090 version of OUTLET, WATER, and is used in some Prius and Prius PHV models in both Europe and Japan from late 2015 on, and some Corollas generally, but nothing in North America.

Googling for it, many sellers are calling it a thermostat housing. I'm skeptical of that, as Toyota just calls it OUTLET, WATER, and there's already a thermostat in the thing they call the WATER INLET SUB-ASSY, W/THERMOSTAT.

So I don't have any explanation of what the electrical gray part does. Anybody with access to a European or Japanese New Car Features manual for an appropriate year should be able to find out. @Elektroingenieur, maybe?

 

Interesting. Where does that pipe around the back of the engine go?

 

Seeing that the cylinder head is the same part number for Europe and North America, I would guess the North American 16331-37100 version would bolt right on....

I think I would have wanted to find out what it was, not suspect, before making my new engine's cooling depend on whatever it does or doesn't do. The electrical connector looks to have two terminals, amirite? Did you plug anything into it?

There already is a temp sensor in that same assembly (the other electrical connection, aimed forward), which the North American version also has. So that makes the gray thing ... puzzling.

 

Thanks for posting the pic. Where do I start


iPhone ?

 

So do you have that piece (thermostat) pictured on your motor?