RM European Auto Parts
Results 1 to 5 of 5

Thread: M42B18 bent valves with cylinder damage, block still usable?

  1. #1
    Join Date
    Mar 2017
    Location
    Oslo, Norway
    Posts
    10
    My Cars
    E36 320i, E36 318TI

    M42B18 bent valves with cylinder damage, block still usable?

    Hello! I am currently in the process of replacing gaskets and seals on my M42. As i took the cylinder head of the engine i was shocked to see all of the exhaust valves being bent.
    Amazingly the engine was running like normal, just had a rough idle.
    Anyways, the valve on cyl. 4 was so bent that it has struck the top part of the cylinder wall on number 4.
    My question is, if I get a refurbushed cylinder head, is the block still usable as it is, concidering the damage is only above the piston rings (no marks further down).
    IMG_6015.jpgIMG_6022.jpg

  2. #2
    Join Date
    Sep 2006
    Location
    NW suburban Chicago
    Posts
    12,555
    My Cars
    hiss by my window
    If it has raised up any metal around the head gasket fire ring sealing area that would be a concern. Looks like a bit of something may have been traveling between that bolt hole and the damaged area. Be sure it is dead nuts flat there. Also if any raised edge of the damage in the bore you can feel I'd smooth it out as any small bit sticking into the chamber can become a hot spot and promote detonation.
    Other than that it is of no consequence.
    Piston head is concerning, looks like the valve pounded it good and cut that divot(s)
    The top ring land is almost certainly crushed but even if not those edges are bad, see above about detonation. Put a piston on your shopping list too.
    Last edited by ross1; 03-15-2019 at 06:16 PM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  3. #3
    Join Date
    Jun 2002
    Location
    boonies, western NC
    Posts
    21,530
    My Cars
    E39M5, E500 4WD, Subie
    I dunno. I see a big chunk out of the cylinder wall, right at the very top, where all the stresses will be. I don't know about prices in Norway, but here, I'd advise just buying a used motor

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, at an independent, formerly @ dealer
    BMWCCA 274412 SCCA 334928

  4. #4
    Join Date
    Mar 2017
    Location
    Oslo, Norway
    Posts
    10
    My Cars
    E36 320i, E36 318TI
    Thanks for the advise. Ill be taking out the pistons to see if they need replacing. Will also be honing, with new piston rings and have a refurbished head ready to go on. Hopefully it will be allright

  5. #5
    Join Date
    Sep 2006
    Location
    NW suburban Chicago
    Posts
    12,555
    My Cars
    hiss by my window
    The piston you've shown and any others that may look like that are junk, nothing else to see.
    Let us know how it works out, good luck.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

Similar Threads

  1. Cylinder Head Replacement - Bent Valves
    By Talan in forum 1996 - 2003 (E39)
    Replies: 25
    Last Post: 01-30-2012, 02:43 PM
  2. Replies: 19
    Last Post: 10-29-2011, 11:21 PM
  3. Replies: 8
    Last Post: 03-19-2007, 08:03 PM
  4. Help: bent exaust valve; 6th cylinder
    By 325eye in forum General BMW Mechanical Help sponsored by RM European Auto Parts
    Replies: 3
    Last Post: 09-19-2006, 05:09 PM
  5. M50 bent valves; bottom end damage?
    By e36its in forum Track, Auto-X & Drag Racing sponsored by Bimmerparts.com
    Replies: 7
    Last Post: 07-09-2006, 07:34 AM

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
  •