Discussion in 'Diesel Engines' started by urisvan, Dec 14, 2017.

  1. urisvan
    Joined: Nov 2005
    Posts: 237
    Likes: 5, Points: 18, Legacy Rep: 53
    Location: istanbul

    urisvan Senior Member

    i have an old yanmar 2gm20. it was leaking oil and i opened the engine for repair. i need to change the piston rings so i will order ring set.
    but which one? there are two sizes of piston and piston rings. one is standart one and one is OS(oversize).
    if someone knows the exact dimensions of the normol piston and oversize piston please tell me so i can measure my piston and know which one i have...
  2. JosephT
    Joined: Jun 2009
    Posts: 859
    Likes: 107, Points: 43, Legacy Rep: 218
    Location: Roaring Forties

    JosephT Senior Member

    I would suggest 2 things to ensure you order the correct pistons + rings:

    1. Definitely best to use a micrometer and get a precise measurement.

    2. Contact Yanmar to see if the pistons contain a marking or stamp to indicate the size. If they're smart they included the sizing info on the underside of the piston casting.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.