1. Attachments are working again! Check out this thread for more details and to report any other bugs.

high coolant temperature warning after maintenance work

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Ceres, May 19, 2011.

  1. Ceres

    Ceres Junior Member

    Joined:
    Apr 1, 2009
    35
    4
    0
    Location:
    USA
    Vehicle:
    2011 Nissan LEAF
    Model:
    N/A
    Hi everyone,

    I was driving my 2007 Prius on the freeway this morning after picking it up from my mechanic and the high coolant temperature warning light came on for ~4-5 seconds but then disappeared. I was able to safely drive it another 5 miles to work and park. My mechanic changed the engine and transaxle fluids in my car (along with pcv valve and serpentine belt replacement, engine oil and filter change) just before, so we think this could have been due to an air pocket in the coolant system. I will need to check the coolant level once the engine has cooled down and refill if necessary. I plan on driving it around locally before going on the freeway in case the warning comes on again.

    Has anyone experienced this problem before? I read on this forum (belatedly) that it is really hard to bleed the air out of the coolant system. My mechanic is independent so I don't think he has a lot of expertise specific to this issue. I just hope no serious damage has been done to my car. :( Any advice would be extremely appreciated.
     
    #1 Ceres, May 19, 2011
  2. jdcollins5

    jdcollins5 Senior Member

    Joined:
    Aug 30, 2009
    5,131
    1,338
    0
    Location:
    Wilmington, NC
    Vehicle:
    2010 Prius
    Model:
    III
    You are correct that it is difficult to get the air out of the system when the engine coolant is replaced. You did not mention anything above about the mechanic changing the engine coolant.

    If he did change the coolant, then he will need to bleed the air out of the system. Search on here for changing engine coolant. Patrick Wong has a very good procedure on here on how to bleed the air from the engine coolant lines on a Prius.
     
    #2 jdcollins5, May 19, 2011
  3. Ceres

    Ceres Junior Member

    Joined:
    Apr 1, 2009
    35
    4
    0
    Location:
    USA
    Vehicle:
    2011 Nissan LEAF
    Model:
    N/A
    Sorry if the post was unclear (changing the engine fluid/coolant part was buried in the middle of the post), but yes, my mechanic did change the engine coolant (drain/fill) for my 100K maintenance.

    I just checked the coolant level and it was still at the full line, so maybe it was a small air pocket that was there initially and then dislodged? I did read some of Patrick's posts and they were very informative. I do not hear any gurgling or bubbling sound as others have heard.
     
    #3 Ceres, May 19, 2011
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,200
    6,479
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    You might be right.

    When checking the engine coolant level, you need to open the radiator cap (after the radiator has cooled down) to see the fluid level within the radiator itself. It is not sufficient just to look at the fluid level in the translucent plastic reservoir near the radiator.

    To access the radiator cap you need to remove the black plastic cover over the radiator. This is held on with six black plastic "screw" fasteners. To remove a fastener, rotate it with a Phillips screwdriver while applying upwards pressure on the fastener by pulling up on the cover.
     
    #4 Patrick Wong, May 19, 2011
  5. Ceres

    Ceres Junior Member

    Joined:
    Apr 1, 2009
    35
    4
    0
    Location:
    USA
    Vehicle:
    2011 Nissan LEAF
    Model:
    N/A
    Thanks Patrick. I had the car towed back to the mechanic that same afternoon after the warning lights came on and off again this time repeatedly during a short drive on surface streets. I was too afraid to drive on the freeway to the shop. It took almost two hours but my mechanic finally got most of the air out of the system. He drove it around on surface streets and on the freeway (gunning it to 80 mph) without seeing the warning lights come on. I drove it back home (~45 miles) and no lights came on. I did hear gurgling sounds behind the dashboard this time. I think the coolant level did go down a bit since it was topped off at the shop. I will keep an eye on it the next few days. Hopefully tomorrow's drive will be free from any trouble.

    Besides the obvious warning lights, we had other signs of coolant trouble. When we set the fan on high with the temperature at the max level, the air stayed cool. Also, CHS pump made abnormal choking noises while it was running after turning off the car.

    Hindsight is 20/20 and I wish I had gone to a dealership to get the engine coolant changed instead. My mechanic and I both did not do our due diligence and greatly underestimated the difficulty of the task. Many lessons learned today.
     
    #5 Ceres, May 20, 2011
  6. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,859
    1,858
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    I had both coolants refreshed for the second time by my dealer at 150k miles and the same scenario occurred. I also had my 2004 Prius towed back for a redo and top off of the ICE coolant so using a dealer is no guarantee that the work will be done perfectly. Your mechanic is now well trained on this task and should be able to perform it well next time (albeit at a higher price).

    JeffD
     
    #6 jdenenberg, May 20, 2011
    2 people like this.
  7. seilerts

    seilerts Battery Curmudgeon

    Joined:
    Mar 7, 2010
    3,326
    1,512
    38
    Location:
    Santa Fe, NM
    Vehicle:
    2005 Prius
    +1. I think you are far better off cultivating a relationship with your existing mechanic. A good fraction of the horror stories here are due to dealership service foul-ups.
     
    #7 seilerts, May 20, 2011
    1 person likes this.
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,200
    6,479
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    If the gurgling sounds in the dashboard are happening after your mechanic's latest work, then there is still air in the system. The mechanic should have set the cabin air temp to MAX HEAT and run the heater system, while purging air out of the engine coolant system.

    Running the cabin heating system while purging air out of the engine coolant system is not an issue limited to Prius. This should be done when working on any car's engine coolant system.

    How about the coolant heat recovery system? Do you still hear unusual sounds when the CHRS pump runs? If yes, then that indicates that air remains in that part of the system as well. This needs to be fixed or else the engine ECU will eventually log a DTC and the air may cause damage to the system if the CHRS pump overheats.
     
    #8 Patrick Wong, May 20, 2011
    1 person likes this.
  9. Ceres

    Ceres Junior Member

    Joined:
    Apr 1, 2009
    35
    4
    0
    Location:
    USA
    Vehicle:
    2011 Nissan LEAF
    Model:
    N/A
    jdenenberg and seilerts:
    Thanks for sharing your story and advice. You two have a very good point. My mechanic does have the experience now and I do have a good relationship with him. The only drawback is that he does not have the Toyota-specific tools that a dealer might have, such as to monitor the temperature, to run the pumps, etc. I'm not even sure if he is willing to do another coolant change on my car the next time, seeing how much pain was involved this time, lol.

    Patrick:
    Thanks for the insights and help. The pump is sounding normal now, no more unusual choking noises. The air is also back to hot when the temperature is set to max. No warning lights this morning on the drive to work (another ~45 miles), but I can still hear gurgling sounds off and on while driving. I did see my mechanic set the temperature to max with the fan on highest speed while he was trying to purge out the air but maybe he didn't do a very good job of it? He says the residual air will eventually work its way out of the system. Would it help if I ran the heater system myself while driving? In other words, just have the temperature and fan at max settings while I drive around town.

    I think it is time for me to get a ScanGauge just so I can get temperature readings.
     
    #9 Ceres, May 20, 2011
  10. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,859
    1,858
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    I have a ScanGauge and it does give me most of the information I want, but for maintenance work consider an AutoEnginuity (~$500). See:
    AutoEnginuity 9.1.1 report - Page 3 - Hybrid Car Forums
    and ask Bob Wilson any questions you may have as it will allow your mechanic to access the Toyota specific maintenance operatons.

    JeffD
     
    #10 jdenenberg, May 20, 2011
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    18,200
    6,479
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Yes, it would help.

    Since the weather in southern CA is warming up nicely, you may not need to run the heater during your commute. Make the car READY and in P, then rev up the engine repeatedly (3,000 RPM or more) until the gurgling goes away, while the cabin air temp and fan speed are set at max. Hopefully that will only take 10 minutes or so.
     
    #11 Patrick Wong, May 20, 2011
  12. Ceres

    Ceres Junior Member

    Joined:
    Apr 1, 2009
    35
    4
    0
    Location:
    USA
    Vehicle:
    2011 Nissan LEAF
    Model:
    N/A
    jdenenberg:
    That is a bit out of my budget at the moment so I'll stick to the Scangauge for now. But I will definitely keep it in mind for the future. Sounds like a pretty powerful maintenance/diagnostic tool to have.

    Patrick:
    I will try your suggestion tonight. Thanks for all the help and advise.

    I think I would be totally lost without the wonderful people here in PriusChat. Thanks everyone. :)
     
    #12 Ceres, May 20, 2011
(You must log in or sign up to post here.)