Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

crank turning

Discussion in '1982-Present GM Diesel' started by odee1, Jul 27, 2004.

  1. odee1

    odee1 Registered Member

    Joined:
    Feb 27, 2004
    Posts:
    50
    Likes Received:
    0
    I'm gathering parts to rebuilt a 6.2 or 6.5 for my dually that I tow with. I was wanting to know what is the prefered way on the crankshaft? I have heard to turn it down others have said not to even think about turning it. So which way is right?
     
  2. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    I seem to recall reading somewhere that the 6.2/6.5 cranks can't be turned because they have nitrided journals. They can be lightly polished, but not turned down.
    I'm not positive on that, though.
     
  3. AgDieseler

    AgDieseler Certified Scrap Producer Premium Member GMOTM Winner

    Joined:
    Jan 25, 2001
    Posts:
    1,036
    Likes Received:
    1,093
    Location:
    Dallas
    Jarhead is right.

    The 6.2/6.5 cranks are made of nodular iron, and they are heat treated to have a fine pearlitic matrix for excellent ductility. The journals are then nitrided for good wear properties. This combination gives a hard enough surface to resist wear, but a ductile enough core to resist the shock loads of 21.3:1 diesel combustion.

    The nitride layer is only a few thousands thick, and any grinding will remove this wear resistant layer is short order.

    Polishing is okay; grinding is bad. /forums/images/graemlins/smile.gif
     
  4. arveetek

    arveetek 1/2 ton status

    Joined:
    Mar 1, 2002
    Posts:
    722
    Likes Received:
    0
    Location:
    Granby, MIssouri, USA
    [ QUOTE ]
    Jarhead is right.

    The 6.2/6.5 cranks are made of nodular iron, and they are heat treated to have a fine pearlitic matrix for excellent ductility. The journals are then nitrided for good wear properties. This combination gives a hard enough surface to resist wear, but a ductile enough core to resist the shock loads of 21.3:1 diesel combustion.

    The nitride layer is only a few thousands thick, and any grinding will remove this wear resistant layer is short order.

    Polishing is okay; grinding is bad. /forums/images/graemlins/smile.gif

    [/ QUOTE ]

    What he said! /forums/images/graemlins/thumb.gif

    Casey
     
  5. odee1

    odee1 Registered Member

    Joined:
    Feb 27, 2004
    Posts:
    50
    Likes Received:
    0
    So I guess the answer is not to run one that has been turned. I have seen alot of bearings lately on ebay for a crank that has been turned on mains and rods. I thought it might be a good way to save a few dollars on a rebuild.
     
  6. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    Most gas engine crank journals can be turned. The 6.2 crank is made differently though. Wouldn't surprise me if other diesel cranks are the same way.
     

Share This Page