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Mysterious oil leak on passenger side

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    #1

    Mysterious oil leak on passenger side

    So i recently swapped my car with an S52 with around 200k miles. I cheaped out and didn't reseal everything on it. When i pulled the engine from the m3 i noticed an oil leak right in the middle of the block coming from the head on the passenger side. I tried to find the leak, but was only able to trace it to the mating point between the head and block. It is thickest near where the center three return oil galleys are. I replaced the VC gasket and put RTV in the 6 spots. I have felt around the VC gasket and it's dry. I cannot give an estimate of how much it is leaking as i just finished the swap.

    Is there anywhere i am missing or is it the head gasket? There are no other head gasket symptoms and compression was 180 +/- 5 across the board with a cheap HF compression tester.

    I am trying to avoid doing a head gasket as i am getting swamped with class and do not want to leave the car headless in a parking lot for too long.
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    #2
    Head gaskets can fail in a number of modes. A compression check would only show if there were a leak in the fire ring portion of the gasket. The head gasket also seals cooling and oiling passages that are separated from the combustion chamber.

    It would appear that you just have an external oil seep/leak. Pretty common on theses motors by now if still rocking OE head gasket. I wouldn't lose sleep over it unless you have an active leak you can watch accumulate. Keep an eye on the oil level and tackle it when you have more time/space.
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      #3
      I know the PO said that the car had gotten hot one time and he immediately shut it off and let it cool down before going home. He said it never happened again and said it took about 1 qt every 2-3k miles.

      I am wondering if replacing the head bolts one by one would help with this. My theory is that the head bolts stretched a little (maybe the head warped a little) and new head bolts will provide more clamping force to seal the gasket in that area. I have yet to install them, but figured for $20 it wouldn't hurt to try. Do you all have any experience/luck with fixing or reducing a leak this way?

      Also its not pouring out, but after the engine running for 30 or so minutes, it runs down the block to the bottom of the oil pan in the back and starts to accumulate enough to form a drop. I had wiped the engine down with break clean to try and find the leak and that was the results.

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        #4
        Not on these engines. ~2006 N52s had an issue where the torx head snapped off of a smaller head bolt and would leak oil. The BMW sanctioned fix was a new bolt and all the ones I saw resealed, but everything was pretty fresh then.

        With that mileage its almost a certainty that the head could use some machine shop time. Do you have access to a leak down tester and compressed air?



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          #5
          Originally posted by gazellebeigem3 View Post
          Not on these engines. ~2006 N52s had an issue where the torx head snapped off of a smaller head bolt and would leak oil. The BMW sanctioned fix was a new bolt and all the ones I saw resealed, but everything was pretty fresh then.

          With that mileage its almost a certainty that the head could use some machine shop time. Do you have access to a leak down tester and compressed air?


          I also have heard of similar failures on m20's and replacing the bolts one by one solved it. I do not have access to compressed to do a leak down test, but i'm going to start asking around. I think advanced auto/autozones will rent a leak down tester.

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            #6
            So I started on replacing the head bolts tonight. I decided to measure the break away torque of each bolt. The first one I didn’t realize my torque wrench only goes in one direction so I tried loosening a bolt with it and it came out fairly easy. If I had to estimate maybe 35ft lbs. The 2nd bolt I did had a moving torque tightening at about 45ft lbs.

            and yes I know I can over tighten the bolts and bad stuff will happen so I am deciding to stop tightening them to measure after 60 ft lbs

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              #7
              Well I moved onto the next few bolts. One of them sprang a coolant leak which meant one of three things. The head was cracked, warped or the head gasket was very gone. I decided to pull the head and found with visual inspection and some light cleaning the head gasket was gone.

              the condition of the head gasket was awful around the oil return galleys on the exhaust side. The red rubber seal was essentially this thick oily substance that did not seal at all. Near where the bolt hole was leaking coolant the gasket had a break in it.

              I have decided to take it to the machine shop to see what they will say. Hopefully it goes on quickly and easily.

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