Results 1 to 9 of 9

Thread: N52 broken head bolt replacement

  1. #1
    Join Date
    Jun 2006
    Location
    Ashland, KY
    Posts
    194
    My Cars
    E30M3,SE30,E46/92/83/70

    N52 broken head bolt replacement

    I am working on a n52 that has two of the Al head bolts broke. One is outside the valve cover and one is inside under the intake sprocket. I have searched and not found any DIY's on replacement of these. My question is can I remove the big bolt holding the sprocket on and remove the reference disk for better access without having to lock down the cams? I am hopeful the sprocket will stay in place.

    Michael

  2. #2
    Join Date
    Jan 2007
    Location
    .
    Posts
    7,708
    My Cars
    .
    No!!! Do not break that bolt loose! The camshaft can and will turn just from valve spring pressure and the engine will have to be retained. And the banks bolts are one time use.

    So again, do NOT loosen the bolt unless you're prepared to retime the engine. Nothing having to do with the cams, crank, or reluctor wheels is keyed
    Last edited by White94RX; 11-10-2013 at 03:04 PM.
    ASE and BMW Master Certified Technician

  3. #3
    Join Date
    Jun 2006
    Location
    Ashland, KY
    Posts
    194
    My Cars
    E30M3,SE30,E46/92/83/70
    Thanks for the quick reply. I replaced the bolt outside the valve cover and removed the broken bolt head from inside. Is it worth the trouble to buy the tools and lock down the cams to replace this bolt? And if yes, should I replace the bolts that have not broke yet? Engine has 107k miles and got into this mess by starting to replace water pump and fix oil leak at oil cooler.

    Thanks,

    Michael

  4. #4
    Join Date
    Jun 2006
    Location
    Ashland, KY
    Posts
    194
    My Cars
    E30M3,SE30,E46/92/83/70
    Another question. Anyone know the diameter of the crankshaft holding tool? I have a good idea on how to make the camshaft tool cheap. Just need to figure out the dia of the crankshaft tool.

    Michael

  5. #5
    Join Date
    Jan 2007
    Location
    .
    Posts
    7,708
    My Cars
    .
    There are some places that rent the tools. Search for Bimmer Tool Rental. He might have the ones you need. Just know that if you don't do it right, you're risking engine damage.
    ASE and BMW Master Certified Technician

  6. #6
    Join Date
    Jun 2006
    Location
    Ashland, KY
    Posts
    194
    My Cars
    E30M3,SE30,E46/92/83/70
    Well I finished this repair.

    To secure cams: I used two 20mm wrenches to hold the cams in place. I was originally going to weld them in place with a plate but when the engine was timed the two box ends were together so I just secured them to each other and tied them down to the head so they could not move.

    To secure crank: I used a 5/16" bolt 6" long for the crank lock. I cut off the threads and bent the remaining smooth part into a 90*. I did some slight filing to make it fit.

    To time VANOS trigger: I ended up using a piece of Al angle as a straight edge against the top of the head and scribed a mark across the trigger wheel. I also marked a reference from the trigger to the sprocket.

    Now for the repair I had to replace the bolt under the intake cam sprocket. I removed the vanos trigger wheel and left the sprocket in place. Holding sprocket in place with original bolt. Removed the broken bolt with the typical dental pick method.

    To install the new head bolt I had to remove the sprocket but decided to leave the chain tensioner in place. I was able to remove the sprocket but leave it attached to the timing chain. By holding the sprocket and chain off the cam I had room to install the bolt and get the socket on and torque it to spec. I then reinstalled the trigger to my marks and installed a new bolt securing it to the cam. During the final stage of torquing the sprocket to cam bolt the cams moved slightly but the trigger didn't move relative to the sprocket.

    Put everything back together and all runs good.

    Hope this helps someone.

    Michael

  7. #7
    Join Date
    Mar 2010
    Location
    phoenix
    Posts
    122
    My Cars
    96 328i e36
    Nice job !

  8. #8
    Join Date
    May 2006
    Location
    nyc
    Posts
    876
    My Cars
    06 325i 6SP Sport+Prem
    Sounds more than DIY to me, but you odd a great job.

  9. #9
    Join Date
    Jul 2014
    Location
    West Sacramento, CA, USA
    Posts
    5
    My Cars
    2006 BMW 330i
    Thanks so much, I'm going to give this a try!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •