2001 toyota prius Inverter cooling pump fault

No turbulence means that you have no fluid flow. Since you hear the pump running, the lack of fluid flow is due to trapped air in the system.

It is very difficult to get the air out of the Classic inverter coolant system. You need to use both bleed valves and the procedure is to attach clear vinyl hoses to the valves, leading up to the reservoir opening.

There is no thermostat or radiator.

There have been several posts on how to do this. Plan to spend a few hours, and you must not drive the car until this is resolved.

 

There is no radiator for the inverter coolant system.

Although a plugged hose is possible, if the cooling system was working prior to the old pump failing, then the most likely cause is trapped air.

 

1. The pump should be running when you loosen the bleed valves. Then close the valves before you turn off the pump.
2. When you get to the point where you no longer are making progress, try driving the car for a short distance, "around the block". That may help to encourage circulation.

 

I thought this youtube video of the pump cut open was interesting. Is there any way of using a gen 2 pump on a 2001 Prius ?

 

The tricky thing about the Gen 1 inverter coolant loop is that there are (as you've noticed) two bleed valves, and the gist of the bleeding procedure is to fit clear hoses on them that run back to the coolant reservoir, so you can let the hoses fill with fluid and allow bubbles to rise up through them.

The trick is that these two bleed valves are on opposite sides of the pump. The one closer to the outside of the car is on the pressure side, so if you open it while the pump is running, fluid will flow out, which is what you want.

The one closest to the center of the car, though, is on the suction side, and if you open that one while the pump is running, the flow direction will be in. If there is air in your clear tube, you will be letting air into the system instead of bleeding it. Air can also be drawn in around the threads of that valve, if it is opened while the pump runs.

Because of that, the procedure in the Toyota manual never has you open either valve while the pump is on. It has you do a much-repeated procedure where you turn the ignition ON, shake the hoses etc., turn the ignition back OFF, open the valves, let any air escape, close the valves, turn the key back ON, etc. It is very tedious and annoying.

When I owned my Gen 1, I developed a procedure for doing the bleeding while the pump runs. It requires applying enough negative pressure to the hose on the suction side to overcome the suction and keep that fluid flowing outward. As it turns out, the suction at that bleed valve measures no more than about 10 inches of water, so it is enough to use a tube filled with coolant and running to a jug on the ground, which is more than 10 inches below the valve. The tendency to leak around the threads (air in at the one, fluid out at the other) can be solved with a suitable nonhardening sealant on the threads.

The procedure is a lot less annoying that way.

There is, by the way, a radiator for the inverter coolant loop. It is a small one and you can see it down behind the bumper, ahead of the bottom of the main condenser and engine radiator.

-Chap

 

Wanted to share the change out of a failed inverter pump on a 2002 Prius with 323,000 miles.
Overheating inverter on hot days caused the car to shut down. The display screen would flash and go white then the car would die.
Found that the pump was not running even though coolant was at proper level.
While searching for a pump I saw that the series 2 pump was similar but had a different mount.
Since that pump was $60 cheaper I thought I would try installing the series 2 pump into the series 1 Prius.
Found this one on eBay:

TOYOTA *OEM GENUINE* ELECTRIC INVERTER WATER PUMP PRIUS 04000-32528 G9020-47031 | eBay

This youtube video shows the tear-down steps needed to access the pump:

The pump will fit with the following modifications:
Remove the old pump.
Remove the steel mount from old pump and then in a vice, bend the old mount left of the 2 body mount bolt holes lengthwise in an "L" then flatten all tabs.
Match the new pump to the positioning of the pump ports so to line it up with rubber hoses. Then, mark on the old mount the position of the 2 lowest bolts on the new pump (leaving the new steel mounting plate on the new pump).
Drill 2 holes to match the mount holes on the new pump.
Unscrew the 2 lower bolts from the new pump and insert through your drilled holes and secure tight to the old mount plate. You may need to bend back the protruding and unused mounting plate tab so to clear the body support right of the radiator.
A few trial fittings may be required to slightly bend the mount to clear the A/C line and main inverter.
You will find that the 12v connector is different but the female plug will fit easily by nipping off the plastic surround on the new pump taking care not to disturb the 2 male connector prongs.
the 12v plug will have a bit of plastic on the end that needs nipping so that it then seats firmly in place. Be sure to connect the plug the right way. Note how it is attached to the old pump connection. Same orientation applies with new pump.
Using 2 long zip ties secure the plug to the pump and seal with a dab of silicone.

Bleeding was done by repeated squeezing of the large coolant hoses on either side of the inverter radiator until all air burps out of the 2 bleed nuts and you see coolant flowing in the reserve tank. You will need to refill the reserve tank a few times and start and stop the pump. To prevent coolant spilling use clear plastic tubing on each of the bleed screws and allow to pour into a container.

About a 2 hour project with the most difficult part being reattaching the spring clips on the pump hoses and that nasty nut holding the bumpercover on that is to the right of the headlamp shell.
PROBLEM SOLVED!
Good luck!

 

congrats! & Welcome to Prius Chat!

 

I'm in the process of doing a coolant change while replacing an inverter pump on my 2002 Prius. Can someone tell me what size tubing to buy so I can get this on Amazon. I don't have any of this just laying around here.

Also, is there a trick to getting the screw/nut or thingamajig that holds the front bumper to the fender in place off? I can't seem to figure this one out and it's a tight fit. I've pulled back the liner and even my tiny fingers are having trouble. What's the deal here? All the other items came off easy.

 

There's no secret, it's bugger to get out. As I remember, it takes a 10mm open end wrench to get loose. It's not a screw, it's a nut. I have big, 65 y/o hands and managed to get 'em loose, I did both sides when I replaced the front fascia for painting. Actually I did them twice--I found a used bumper cover in a wrecking yard.

 

Anyone ever heard of or had their inverter coolant pump stop working intermittently? Ive checked all my fuses and tested all my relays and everything checks out good. But for the second time in a week my coolant pump stops working. But if I let the car sit it starts working again.

 

I'm ready to get a saws-all and then get some gorilla glue to put it back together. Screw the nut! This is the most insane thing to remove. But I'll keep at it as I just can't see towing the car to a dealer to get the screw removed to do this repair that many DIY'ers do themselves. And I've got a can-do attitude so we will get it done, somehow! The inverter pump arrived today.

 

If you cut the tab on the bumper cover, nothing will repair it. (I know from experience. It can be done Sandy, from inside the fender with the inner fender pulled back. The headlite is kinda difficult to remove, too.

Good on you for trying. I know so many people who have to take their cars to dealers or indy shops for the slightest repair. Women who can work on their own stuff have always seemed empowered and fascinating to me.

 

That's good to know. I haven't tried anything yet. I was only thinking of cutting the screw, not the tab, if that was even possible. First, I'd have to acquire a saws-all or get my handyman back here. I didn't have the energy to tackle it yesterday and I'm not certain if I have a small enough hex wrench.

I have a boatload of assorted tools from my dad since he passed in 2010. My other car is my dad's car, a 1/4 mile street race car with a 460 motor, a '72 Mustang Mach 1, now 11 seconds, which I also grew up with going from 16 seconds stock to 13 seconds with a small block at the time as a passenger down the drag strip at OCIR. So you can imagine I have a lead foot, at times. I've slowed down as I've aged and retired, but trust me the Prius hums right along at 100 mph on trips to Palm Springs with a radar detector..... with excellent MGP to boot! LOL

TODAY MIGHT BE A GOOD DAY TO TRY THE BUMPER, again. Wish me luck.

Thanks for the continued help.

 

I also ordered 2 gallons Asian coolant which arrived yesterday from Amazon so will attempt to do the coolant change as well. Watching all of the YouTube videos has really inspired me to do much of this myself. I'm on a very limited budget with much time on my hands these days. It seems I should really tune up this car as much as I can since it has 93000 miles on it and let the repair shops do the big stuff. I intend to hold onto the car. I've had several people stop me and ask me if I want to sell it.

 

It's 10mm

 

Brian, will this socket work. I have a 3/8 drive drill. Do you think I can get it wedged in there and it will solve my problem? Apparently it's available from Home Depot.

 

Sears, Autozone, O'reilly's, Ace, Harbor Freight, etc. all sell ratcheting flat box end wrenches. A 10 mm is what you need to get in far enough to remove the fastener. The tool you showed would not work.