Inverter coolant level issue

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by kissinger, Jan 4, 2016.

  1. kissinger

    kissinger New Member

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    Hey guys.

    So while driving the other day I got a warning light on the dash followed by a high coolant temperature icon on the info display. I made it home and checked under the hood and noticed that the level of the inverter coolant was way low. I topped it up and the car started working fine again, but having checked the level again yesterday I noticed that it's already an inch or so below the max level which I filled to just 2 days previously. Is it safe to surmise that I have a leak in the system?

    I did have a service and some work done on the water pump around 2 months ago, at which point they replaced the coolant. Someone suggested that the coolant could originally have decreased because of air in the system, and my not noticing prior to getting the warning light could have introduced more air into it, which has caused the topped up coolant to decrease yet again. I wonder how feasible that is. Anything in particular I should do besides keeping any eye on it? Anyone experienced this issue before and know what kind of bill I'm in for?
     
  2. Eclipse1701d

    Eclipse1701d Prius Enthusiast

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    I did have that issue with my '07 after I had the inverter coolant changed. I brought it back to the dealership and had them finish the job, air out, etc. However, if you top it off, again, and the same issue appears, take it in immediately. You do NOT want low inverter coolant. The inverter is very expensive to replace.
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, it sounds like the inverter coolant loop may have a leak. Fill the level up to full again. If you see the level drops yet again, have the system checked out.

    Assuming a leak exists, the repair cost will depend upon the component damaged. It could be GBP50 for a damaged hose or could be GBP3,000 to replace the transaxle.

    Or, maybe a hose at the recently replaced coolant pump is loose which would show poor workmanship. Look at the pump which is immediately behind the headlamp assembly on the left side of the car (passenger-side in UK). Do you see any pinkish stains around the hoses which would show a leak.
     
    #3 Patrick Wong, Jan 4, 2016
    Last edited: Jan 4, 2016
  4. Britprius

    Britprius Senior Member

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    As well as the things listed in the above posts I would also check the engine coolant in the radiator. Not the header / expansion tank!!!
    The radiator cap is under the plastic front engine cover, and is the forwards most filler cap. This should be full to the brim.
    Under certain conditions the header tank can remain full, but the radiator it's self can become low. This is usually due to a leaking engine coolant pump again the thing to look for is pink crystals inside of the coolant pump pulley, and in a strait line on the underside of the bonnet above the pump drive belt.
    The UK engine coolant system requires less fluid than the US version, and is easier to bleed. This is due to the fact that the UK Prius does not have an engine coolant thermos tank as in the US Prius.
    Use only Toyota SLLC coolant in both systems.

    John
     
    #4 Britprius, Jan 4, 2016
    Last edited: Jan 4, 2016
  5. kissinger

    kissinger New Member

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    I checked the hoses at the front there and I couldn't see any signs of any leakage. I've also just topped up the coolant once again to the max level so I'll see how it looks in a day or two and I should have a better idea then of whether or not I'm in trouble.
     
  6. kissinger

    kissinger New Member

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    The frontmost cap I can see is the one that's labelled 'Engine coolant reservoir' in the manual, and it's not that one? I will see if I can get the plastic off the front of the engine tomorrow when I've got some light and check it out.
     
  7. JC91006

    JC91006 Senior Member

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    did you check under the car to see if anything is leaking? I once had an issue with the drain bolt not being tight enough.

    You replaced the inverter side pump 2 months ago right? Not the engine side pump?
     
  8. Britprius

    Britprius Senior Member

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    You are reading that correctly. The expansion tank is meant to as a reservoir, but the only way it can top up the system is if there is some vacuum in the system. Any leak that causes a loss of fluid will also allow air back into the system when the engine cools. Drawing air is easier than drawing fluid so the system gets topped up with air.
    There may be no fault with the engine coolant level, but having had a warning for overheating, and it is not clear which coolant loop overheated it would be prudent to check both.

    John.
     
  9. kissinger

    kissinger New Member

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    The documentation I have simply states 'Water pump and coolant replacement'. I wonder if the 'water pump' is the pump that's connected to the inverter coolant reservoir? In which case, the fault might be a result of bad workmanship and they might rectify it for free/low cost? I could do without another big bill right now.

    Edit: oh, and just to update: I went on a fairly long journey in the Prius last night -- around 40 miles -- and I got another warning light on the way back. Pulled over, checked under the bonnet and the inverter coolant reservoir had once again lost around an inch and a half of fluid. I topped it up again and managed to get home alright, but safe to say now that I have a leak?
     
  10. andrewclaus

    andrewclaus Active Member

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    I'd check with the shop and verify which pump they replaced.

    But first I would look in the inverter coolant reservoir with the car "IG-ON" (push the button twice, foot off brake) and check for turbulence. If you cannot see any turbulence, the system is not bled correctly and I wouldn't drive it any more. You should also be able to hear the pump running with a smooth, quiet hum, no turbulence.

    Are you able to look down near the front left wheel at the inverter pump itself? You said above there were no leaks at the hoses in front. If any workmanship-related issues exist, they'd be at the pump itself. This is a relatively small, simple system, and leaks should be pretty easy to find with a little poking around with a torch. If everything is obviously dry, there may be an internal issue with large air pockets.

    Good luck with it.
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It would be very safe to say there is a leak in the system that needs to be fixed.
     
  12. kissinger

    kissinger New Member

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    Thanks I will look into this tomorrow before going to the garage. Just to check what you meant by the above (in bold)? I mean, I should turn it on and there should be no turbulence, and if there is turbulence there's a problem?
     
  13. Britprius

    Britprius Senior Member

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    In ready mode there should be turbulence. If there is no turbulence the pump has a problem or there is an airlock in the system.

    John
     
  14. Britprius

    Britprius Senior Member

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    If the pump has been changed in the last year it is under guarantee. All Toyota replacement parts have a guarantee so take the invoice with you.

    John
     
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