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Cracked Head or Cracked Block?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by unsane, Aug 9, 2002.

  1. unsane

    unsane Guest

    My 89 jimmy ate up all my coolant and sent it out the tail pipe. Made me look like some kind of circus act driving down the road. My question is - is it more likely to be a cracked head or a cracked block? the motor is the standard L05 350 tbi stock motor with 150k on it. what was weird is the motor started to get hot one day so i replaced the thermostat. Ran good for about 2 days, then the radiator popped like someone shot it with a 22 longrifle or something, so I put a brand new radiator in it and again it ran fine for a couple of days then started to get hot again. well before I managed to get home the i stopped and left it at a friends house. the next day I went and checked the coolant and topped it off and headed for home, as soon as i started it white smoke(coolant) came bilowing out the tailpipe. I drove it approx 2 miles until it started to get hot again then parked it and had it towed on flat bed home. I looked in the radiator to my suprise all the coolant was GONE, 2 miles and burned it all up!!!! what is more likely to be cracked? Thanks for any help! -Eric
     
  2. Muddytazz

    Muddytazz 1 ton status

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    Could be either really, but I would check the oil to see if there is water (antifreeze) in the oil, if its in the oil, its more than likely (but not always) a cracked block.
     
  3. unsane

    unsane Guest

    Yeah I checked the oil, it was looking OK, but I pulled the valve cover and it looked like a mud pit in there, I am praying it is only a head. I am pulling the motor anyway though to do a rebuild or get a new motor in worst case senario. Thanks -Eric
     
  4. Muddytazz

    Muddytazz 1 ton status

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    you can have your heads (block even) magnafluxed to check for cracks.
     
  5. unsane

    unsane Guest

    with a leak that bad, should I be able to see it with the naked eye?
     
  6. Muddytazz

    Muddytazz 1 ton status

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    All depends on where the leak is at. It could be in a spot where its not visible, but it doesn't hurt to try and look yourself.
     
  7. alec78

    alec78 1/2 ton status

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    To narrow it down a little, pull the spark plugs, granted they have some age to them. The cleanest one is the offending cylinder. If two are clean and next to each other I'd bet you dogged the bullet and its only a blown head gasket. If they all appear clean or the same level of age, do a compression test. It might show them to be next to each other, again being a head gasket.
     

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