Gen 1 Inverter Coolant Change: Is there a better way?

After reading all the posts about how painful the inverter coolant change is for a Gen 1 Prius, I'm wondering if we can instead take advantage of the inverter coolant pump to make the job easier.

I'm thinking about disconnecting the coolant return line from the inverter reservoir and instead routing it to a bucket. Then having an attentive assistant (aka the wife) turn the ignition key so that the pump starts up (with the engine off, of course). Then continuously pour fluid into the reservoir as it empties until a gallon (or perhaps a bit more) has cycled through the system. Then having the assistant turn the key off; thereby never allowing air to enter the system and avoiding the need to bleed (tediously).

Has anyone tried this? I suppose if there were some large reservoir within the system (other than the one up top), the old and new fluid could start mixing significantly and throw a monkey wrench in this thought experiment. This could be offset by cycling an extra gallon or so through the system. (after all 20 bucks of fluid beats several hours of tedious labor and driving the car around the block).

I'd probably take the opportunity to upgrade from TLLC to TSLLC, so the color change might server as a useful marker for how well the coolant is cycling.

If I get some positive feedback, I might try this out and report back the results.

 

Thanks for the feedback.

I might replace the inverter pump while I'm at it. The flow is pretty weak compared to the 'turbulent' flow most people comment on seeing in the reservoir (the flow seems to more or less trickle from the inlet, although i still get the noticeable change in fluid level in the reservoir). Anyone know what the typical lifetime is for these pumps? My prius is a 2002 and has 125k miles. The pump is likely the original.

 

Lol, well I guess that's why I'm considering replacing it before one of those bullet points occur. Considering its supposed to be 15 below tomorrow, I'll probably put it off a few days.

 

I choose to view it the same way as replacing the water pump preemptively with the timing belt on a traditional car. Might as well play it safe, especially since it seems to be a pretty straightforward repair.

I'll probably find someway of blocking/pinching off the lines when I replace the inverter pump, so that i can still try out the coolant change method in the original post.

 

Warmer weather finally came.

The answer to my original question is: If you're replacing the pump, you're going to let some amount of air in, so you'll have to bleed anyways. (if you aren't, I still think it would probably work)

When I replaced the pump, I managed to block off the tubing going in and out of the pump just fine, and only lost about a 4-8 oz of coolant, but that was enough to give me a fair amount of gurgling. So I decided just to do a standard drain and fill from there. Now the pump is blasting coolant through the resevoir at a rate that is bewilderingly fast compared to the trickle I had before.

My suggestions on purging the air out the sytem:

1) At first you're going to wonder if the new pump is bad, because it will sound awful. You have to get it pumping liquid in order to get things moving around, best way of doing this is by doing #2:

2) If the pump is running loud at any point and will not correct itself, you have to play around with the lines coming into/out of the pump. There are two tubes coming out of the pump, one goes down to the bottom of the transmission. For convenience I'll call this the "bottom line". The other goes across the front of the car, right underneath a larger coolant line (for the engine presumably) and into the left side of the inverter near the top. I'll call this the "top line"

Gather up as much of the bottom line as you can, and pull it up as high as you can. This seemed to be the best method of getting the pump to start pumping liquid again (probably due to some siphoning effect). Just play around with the bottom line and the top line, lifting up, pushing down, and squeezing, and you'll keep getting tons of air out. Keep topping up the reservoir as you go along (and keep doing this through the whole process, clearly). Eventually, you'll have the pump running smoothly and perhaps even a good amount of flow in the resevoir. Once this stops being productive (producing air/emptying coolant resevoir), go to#3:

3) Using some 1/4 ID tubing, run these from the bleeder nipples to the coolant tank. Start with the one on the right, since it is at positive pressure. Crack it open till fluid fills it all the way up, then close it. Now take this tube off the right bleeder and put it on the left bleeder. You do this because the left one is undoubtedly in suction when things are running right and you don't want to suck air in. Now put your other tube on the right line. Open both bleeders. If you did things right, both should be completely filled with coolant with only small bubbles, if any. (don't open the bleeder to much, because they'll leak/suck from the threads too)

4) From here, try to get your pump pushing liquid (its really quiet when it is) by manipulating the top and bottom lines (pulling up on the bottom line as much as possible seems to work best.) Once its pumping good, start squeezing the top line with both hands until the pump starts making crappy noises again. Make the pump all better by pulling up on the bottom line. The whole time you should be noticing air bubbles come from your bleeder tubes occasionally. Keep alternating until you stop producing bubbles. (side note, I was able to access both of these lines from the top even with the car entirely put together)

5) Once this is no longer productive, close the bleeder vales and turn the pump off (ignition key off). Let it sit for a few minutes while you do something else. Come back, start the pump again, open bleeder vales and repeat #4. Keep doing this until you can no longer make your pump gurgle at any point in the process. At this point, you should be good to go (as near as I can tell).

Doing the above should take you relatively little time (30 min to an hour, I'd guess). Oh, and if you have a battery trickle charger, hook it up before you start, otherwise you'll run the battery dead (like I did)

Speaking of which, after replacing the pump, doing the above purging process, and having the 12 V battery run nearly dead, I have a check engine light. My bluetooth scanner (with torque) won't pick up a code at all. Not sure what the deal is here (i've picked up a code in the past), if anyone as suggestions, I'd appreciate it.

Hope this helps someone!

 

Check Engine Light was off this morning, so I drove it to work. Everything seems fine on that end. I imagine it was some low-coolant or battery-dead related code, which cleared itself up.