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Thread: 2000 e39 528i overflow coolant tank Rod indicator broken off

  1. #1
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    2000 e39 528i overflow coolant tank Rod indicator broken off

    Okay I guess this almost 20 year old car is starting to show it's age. Now the Radiator overflow Rod in the coolant tank broke off from it's float. I tired to fish it out but no luck, even with removing some of he coolant. So I don't think it can make it past the bend in the output hose to the pump? Am I correct? Also now that it's broken off is the a way to tell for now how high the fluid should be in the tank by looking down into it? I see the float it's up against the holder for the Rod / Float. Also I'am I correct by just looking at the system I should have to drain the whole system to replace the tank?

    Thanks

  2. #2
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    You have a major issue. The float is the "canary in the coal mine." It's an early indicator that you need a cooling system overhaul. If any other components fail, and you lose coolant, you will toast the engine: the I6 is VERY sensitive to overheating.


    Ed in San Jose '97 540i 6 speed aspensilber over aubergine leather. Build date 3/97. Golden Gate Chapter BMW CCA Nr 62319.

  3. #3
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    Luckly I was able to fish the rod out.

    Quote Originally Posted by edjack View Post
    You have a major issue. The float is the "canary in the coal mine." It's an early indicator that you need a cooling system overhaul. If any other components fail, and you lose coolant, you will toast the engine: the I6 is VERY sensitive to overheating.

  4. #4
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    Quote Originally Posted by riverjamie View Post
    Luckly I was able to fish the rod out.
    I don't think that's the issue edjack was referring to. The broken rod is a symptom, not the problem itself. The plastic cooling system has given you an unusual warning before fully self destructing.
    98 328is
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  5. #5
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    Quote Originally Posted by edjack View Post
    You have a major issue. The float is the "canary in the coal mine." It's an early indicator that you need a cooling system overhaul. If any other components fail, and you lose coolant, you will toast the engine: the I6 is VERY sensitive to overheating.
    Well, not necessarily.
    The red rod indicator may have broken because you were over-filling the expansion tank with coolant. That puts extra pressure on the whole cooling system when it heats, to the point of breaking the weakest part -the plastic rod.

    So, I'd flush the coolant, refill -and do NOT overfill it- and bleed it out....and hope for the best.
    Last edited by Chedley; 04-23-2019 at 10:36 PM.

  6. #6
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    Quote Originally Posted by Chedley View Post
    Well, not necessarily.
    The red rod indicator may have broken because you were over-flowing the expansion tank with coolant. That puts extra pressure on the whole cooling system when it heats, to the point of breaking the weakest part -the plastic rod.

    So, I'd flush the coolant, refill -and do NOT overfill it- and bleed it out....and hope for the best.
    This is NOT true. edjack is correct.
    The RED rod broke b/c of age.
    The coolant tank will split open soon.

    Search forums for "Cooling Overhaul" for parts recommendation (such as HEPU water pump, Wahler thermostat etc.).
    I wrote the DIY in this forum and bimmerfest.

  7. #7
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    Yikes! The sky is falling.
    Overfilling causes the indicator rod to break? A broken indicator rod is harbinger of death?
    To answer the OPs question: The rod more likely get poked down into the reservoir, usually it gets pushed too far down and that's all. In one piece it will just remain, somewhere , in the reservoir forever. If in pieces who knows.
    You can change the tank without draining the entire system, just have a catch pan ready as you will spill the contents of the reservoir and some from the hoses.
    Last edited by ross1; 04-24-2019 at 08:58 AM.

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