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Thread: '98 Z3 1.9L Radiator Failure

  1. #1
    Join Date
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    1998 BMW Z3 1.9 'Vertibl

    '98 Z3 1.9L Radiator Failure

    -1998 BMW Z3 1.9L M44
    -63km (40k miles)
    -Unknown number of previous owners

    Catastrophic radiator failure at a a red light today, boys. Drove about 30min/15miles at 88degrees F, and had intermittent AC problems about 10 minutes into the drive - air blew hot randomly, but seemed to get colder when we were moving. Then, at a red light, there was a loud pop under the hood, and vapor/smoke bellowed out. Shut the engine down and pushed it out of the way. Pics:





    Towed her home, and ripped out the radiator and fan to get a good look at it. When I pulled the fan, I noticed the bottom electrical connection had some damage, and don't know if it's from the radiator blowout pushing back on everything.





    So, I think I have my head wrapped around the problem - already looking at ordering new radiator, expansion tank, hoses, and the forums are recommending replacing the water pump, thermostat, and belts while I'm at it. But, is there something else that may have caused this? Am I about to replace everything just to have it blow out again?

  2. #2
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    Arida Zona
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    z3
    In my experience the most common causes for radiators to blow like that is overfilling, or not enough airflow. Both situations cause the pressure in the system to rise. Given the a/c issues you describe before the failure, and the failure occuring at idle, it sounds to me like there is a good chance your fan was not working properly.

  3. #3
    Join Date
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    E36/7 E36/8x2 E46 F25
    I would hazard it was both. Overfilled, so when the fan failed the pressure took off.

    Replace the heater outlet neck on the back of the head. They fail and are the #1 cause of melted M44s.


    /.randy

  4. #4
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    Thanks Randy, this thing?


  5. #5
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    Yes, that's one of the two plastic pieces that fail catastrophically. The other is, unfortunately, under the intake manifolds. But, once the manifolds are off, you can get to all the vacuum hoses and other things that need replacing for a total cooling system (and vacuum) restoration.
    Claude Berman, 96 Z3 Production Date 2/96 BMW CCA# 581686
    The only good is knowledge and the only evil is ignorance. Socrates, 469399 B.C.E

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