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Coolant Flush Procedure

Discussion in '6.9L IH & 7.3L IDI Diesels' started by RSchanz, Nov 30, 2020.

  1. RSchanz

    RSchanz Full Access Member

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    There isn't a way to double check that the Tstat is working is there? I have no reason to believe it doesn't. I'm still running stock gauges so... useless.
     
  2. Slicknik

    Slicknik Full Access Member

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    If your thermostat wasn’t working your truck would over heat, and the upper rad-hose would be cold/not hot.

    If your running the same coolant you don’t have to 100% flush. just drain the radiator fill with distilled water drive it hard to get heat in it to open the radiator then drain. You’ll have to do it 2 or 3 times (or until you see only water, helps if you have an refractometer ) but beats not removing plugs/thermostat/heater core line .
     
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  3. RSchanz

    RSchanz Full Access Member

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    I'm switch from basic green to fleet guard. At least thats the plan. If I'm doing that then you recommend removing plugs, Tstat and heater core?


    ayyeee yayyy yaaayy
     
  4. Slicknik

    Slicknik Full Access Member

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    If your switching coolant then you would have to make sure all coolant is out 100% by flushing it with distilled water until you only have water in the system, which takes more flushes then it would if you removed the thermostat and block plugs that’s all , the removal/install heater core is easy just messy.
     
  5. RSchanz

    RSchanz Full Access Member

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    My gut feeling is that I would prefer 5 flushes over removing the tstat. It seems like a lot of added work. I have no idea how to remove/reinstall the heater core. A fairly quick search didn’t reveal any info either. Would you mind sharing how to do so? Maybe I will do radiator, plugs and heater core.

    side note, how exactly does removing the tstat affect the flush?
     
  6. Stu Bailey

    Stu Bailey Full Access Member

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    Yes! In hindsight I would have just sent it the first time and it would have opened and I would have been done with my flush way sooner than I was!
     
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  7. RSchanz

    RSchanz Full Access Member

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    Stu, were you changing fluid type or just re-upping the fluid?
     
    Last edited: Dec 2, 2020
  8. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Why are you thinking about removing the heater core? Are you replacing it? If not, then I don't see any reason to remove it. Don't you want to flush it out too? It's easier to leave it installed and have the heater on with the temp set at max. As for removing it, it's real easy. Remove the heater hoses (naturally) remove the glove box. You'll see a cover behind the glove box with 6 or 8 (I think) screws holding it on. Remove the screws and cover and then the heater core just pulls out. It doesn't take very long at all. Removing the heater hoses is usually the worst part about that job.
     
  9. RSchanz

    RSchanz Full Access Member

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    I wasn't planning on doing so but was only wondering after it was mentioned above as a possible thing to remove when flushing. My previous research lead to the same idea, turn heater on max sit and wait (or drive) for the thermostat to turn on, shut it down, let it cool drain and repeat.

    The whole process is going to be slightly delayed because the radiator was damaged by FedEx so I had to order another.
     
  10. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Hopefully on their dime! By the way, I think that Fed Ex is just about the worst way to ship anything. Onetime I tracked a package that I was really wanting. It took 24 hours for it to move 20 miles with Fed Ex. I'm ALWAYS surprised on the few occasions that a package actually arrives on time with them.
     
  11. RSchanz

    RSchanz Full Access Member

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    Definitely on their dime!

    Funny you say that, it was delivered a week late each morning they would say it would be delivered that day and it would never come. I had a few phone calls and fairly choice words with people. It really sucks that you have to be pushy to get things. Otherwise, they walk all over you and tell you that they don't have information. Finally it arrives and its broken... hahaha
     
  12. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Sounds kind of typical.
     
  13. dan-o

    dan-o Registered User

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    I just switched coolant from green to Fleet Charge. I didn't know if there was any DCA in the coolant. The test strips were damn near half the price of the new coolant, so I just flushed the system 5 times with distilled water then put in 4 gallons of Fleet Charge, which filled it up.
    My thermostat was working, but I was worried about cavitation eating the block. I didn't pull the thermostat. It seemed like a can of worms that I don't need to open at this time.
    My heater doesn't get as hot as my gasoline trucks' does. But, since this is my first diesel, I've read that it is normal for IDI's to run that way. I'm thinking of using a radiator cover to help get some heat in the cab for the wife.

    NOW, WTF should I do with all that old coolant????????
     
  14. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    It does help. Last year, for the first time, I put a piece of cardboard in front of the radiator. It covered about half of the radiator and it did make a difference in how well the heater worked.
     
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  15. RSchanz

    RSchanz Full Access Member

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    4 gallons fleet charge plus 4 of distilled water right?!?! I bought 50/50 premix as that was all the local Napa had. Should be 8gals total
     
    Last edited: Dec 2, 2020

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