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engine teardown from overheating

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    #1

    engine teardown from overheating

    picked up another project that had issues with over heating, heres some info on the car.

    - 270k milage
    - bubbles in coolant revisor and a lot of smoke and hot pressure out of bleeder
    - loosing coolant i think (filled it up two gallons)
    - no white smoke i think (just let it idle didn't what to risk damaging the head)
    - car idles but has symptoms of bad misfire
    - milky residue on oil cap and dip stick
    - oil seems watery but no positive
    - coolant seems clean

    i just assumed it had a bad gasket or a cracked head so i pulled it. tell me what you think. what can cause the bubble and pressure in the coolant system? head gasket and profile gasket look perfect. cylinder 2 exhaust port are a little opened and cylinder 3 intake port are opened. could be lifter or??
















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    #2
    Pretty interesting.

    The valves are open because of the cam positions. There could be issues with the gaskets between the lower timing case and block. Water is getting to the oil somehow. If there were combustion gases getting into the water system it sometimes will cause a hose to blow or split the radiator due to the added pressure. Unless it's a really small amount.

    Before the hed was pulled Was the thermostat replaced? Water pump still good?

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      #3
      Actually it looks like water/pressure may have been going across on 3 on the exhaust side. That may be the culprit.

      If water has made it to the oil and it's run, the rod/crank bearings have been through some hell.

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        #4
        thermostat and water pump can cause air bubbles/pressure in the coolant? bubbles were consistent from start and rev.

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          #5
          No, I was just wondering. What I said in my last post is looking more and more like the issue.

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            #6
            yeah it does look like 3 is leaking, those valves also have the most crap on them. can worn out piston rings be the cause of all my troubles?

            Comment

              #7
              No, but the scoring on the 3 side of 2 is a good indicator of a high mileage motor.

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                #8
                If you are that far into a teardown, I recommend looking at your thrust surface on the crank. My engine had 170k and it was grinding away into the crank thrust surface. Due to the 180deg thrust bearing this ended up being a semi common problem. One BMW has rectified since as they now use 360deg thrust bearings. I had to have my crank welded and nitrided just to get the engine back to factory tolerances.
                1991 BMW 318is Track Car-NEEDS ITBS AND STANDALONE!!
                1997 BMW 328i Daily Driver-like buttah..

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                  #9
                  thats for the advice carnurd. this bearing is the one on the oilpan side? if so there is some wear but it still has the silver coating. hard to believe at 250k+ so it might have been replaced. either way the piston still hold oil in them with slow leakage so im going to replace the head. thanks

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