oil in radiator

Discussion in 'Mechanic and Repair' started by Olylawnboy, Jun 19, 2007.

  1. Olylawnboy

    Olylawnboy LawnSite Senior Member
    from Oly Wa
    Messages: 311

    I have a "90" F-250 7.3L Diesel 4x4 that just started showing oil in the radiator. I'm afraid to ask but, what does this mean? What's failing? I've never seen this in a gas motor before.
    And at less than a hundred grand on a diesel I would like to think a major overhaul would not be needed. I can hope right :) Oly
  2. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    If it has an auto tranny with the fluid cooler integrated in the radiator then it could be leaking. You can plug one end of the cooler then apply compressed air to the other connection. Then look for bubbles in the radiator. If it doesn't have a cooler in the radiator then I would guess it's head gaskets.
  3. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Messages: 752

    The 7.3 has an engine oil cooler. I would suspect that first.
  4. TGM

    TGM LawnSite Senior Member
    Messages: 931

    if it's not the oil cooler, than it could be a blown headgasket, cracked head, or cracked block.
  5. maintenanceguy

    maintenanceguy LawnSite Member
    from NJ
    Messages: 156

    Is there water in the engine oil? the oil would look frothy. (head gasket)
    Is there water in the trans fluid? (trans cooler)
    Do you have white smoke (steam) coming out of the exhaust? (head gasket)
    If you run the motor with the radiator cap off, do you see bubbles? (an occasional bubble is normal) (head gasket)

    I'm leaning toward trans cooler also.
  6. JohnL

    JohnL LawnSite Member
    Messages: 8

    It can depend upon what type of oil that you are talking about as to which cooler is defective.

    If you have oil, be it transmission or engine, in your coolant, then you have a bad cooler in your radiator. Since the oil pump is operating at a greater pressure than your cooling system, the oil is able to leak into the cooling system. (A cooling system with a bad transmission cooler will turn the coolant into a pinkish mix. That is why transmission fluid has the red dye in it. On the other hand, a bad engine cooler will have the coolant and engine oil trying to separate from the water with a grayish appearance.)

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