Inverter coolant is slime, worried about pump

Hi folks,

I was replacing the spark plugs today in our 2002 (180k miles) and decided to peak in the inverter coolant reservoir. The coolant looks like a thick slime, sort of like Pepsi-bismol. There are others on Priuschat that have reported this about their coolant. I'm sure it's way overdue for a coolant change, which I plan to do.

The thing that worries me is that there's very little movement in the reservoir when the pump is running. The videos on YouTube show vigorous sloshing, all I see in mine is a very slow swirling. I can hear the 'aquarium pump' sound coming from the pump.

We haven't had any codes or symptoms associated with the inverter, but if the pump is toast I'd like to replace while I'm in there.

Here's what I'm thinking..
Either the pump is fine but can't circulate the coolant because of viscosity or clogged hoses, or the pump is toast and I should put a new one in when I do the coolant.

Obviously I could flush the coolant and see if it resolves the issue, but I'd rather not do it twice. Anyone have a clever way to diagnose this?

Also, it's a balmy 10*F today here in Wisconsin, if temps can effect things. I assume the pump is just on or off, and shouldn't be less vigorous on cold days.

Thanks for your time!

 

Yeah, Pepsi-bismol sounds like the worst thing ever.

We've had the car 1.5 years, no history before that.

Thanks for the quick response! I'll see if anybody around here is equipped for the job. I expect a shop that does radiators could do it, time for the regular coolant too..

 

I pulled some coolant out with a straw. Definitely more of the white jelly type once I got it out of reservoir. The slime was actually just a thin layer on top, the coolant underneath looks normal. The thinner coolant underneath was actually circulating a bit more enthusiastically also. Of course there could still be gobs of the stuff clogging the passages of the system..

I found a shop that will do it, but they don't have a pressurized flush system, they just drain the coolant, run water through until it comes out clean, and then drain and fill with coolant. Does this sound sufficient?

The mechanic seems knowledgeable, though he's never flushed an inverter, says it'll probably be around $100.

He also suggested (as a pump diagnostic) that I could add coolant (perhaps siphoning down the reservoir first) to see it improves circulation. Since the capacity is only 3 quarts, I could actually get a decent % of fresh coolant in.

 

This great info. I'm going to get some fresh coolant in there and see if the pump performance improves. I guess I shouldn't be surprised, but finding the coolant might slow this project down. No parts stores here have it. Nearest dealership is a ways away and buying online would take a few days too. Makes me wonder if a shop would really use TLLC/TSLLC or just something passably close.

I picked up a flexible funnel and some tubing. If I can do it without making a mess I hope to use the tubing to route the old coolant coming back to the reservoir into a container and have the pump pull fresh coolant into the loop. I thought it would give me a better idea of the flow rate and how nasty the coolant is.

 

Update: I actually took care of this a while ago, but Tapatalk isn't working on my phone so I haven't been back.

I rigged up a funnel and hose so I could pour fresh TSLLC into the intake and divert the old stuff into a container. Obviously not as thorough as a drain-flush-refill, but since the old and new coolant didn't mix in the reservoir and I ran a gallon through (capacity is 3 qts) I think it was effective. And I didn't have for worry about bleeding air out afterwards. The old coolant was a dark color, and perhaps a bit thicker than the fresh, but nothing like the slime I was dreading.

Anyway, the pump did seem to pep up a bit. I should have timed it, but I'd guess it took 2 minutes to run a gallon through. Meaning (very approximately) .5 gpm, which seems low to me but I couldn't find specs on what the should be. I have EngineLink, so I'll just keep an eye on the inverter temps. Unless I see a drop in performance, I'll wait till spring to replace the pump.

The car is throwing the dreaded P0420 (catalytic converter) which is competing for my attention. Thanks again for all the input.