Logo
Get instant online access to repair manuals for your Mercury / Mariner outboard. Online Manuals
MercuryMariner
Order printed Mercury / Mariner service manuals — shipped to your door! Printed Manuals
MercuryMariner
Use engine diagrams to find & order parts for your Mercury / Mariner engine. Engine Diagrams
MercuryMariner
Find parts quickly with Mercury application guides. Quick Parts Guide
MercurySierraCDI
Results 1 to 4 of 4
  1. #1

    Default Merc 9.9 2 stroke water ingestion lower cylinder

    I have a 89 Merc 9.9 That runs rough at idle and higher speeds. Lower plug always looks wet/grey emulsion and with small water droplets

    Compression good at 105 PSI in both, gas is fresh and 50:1
    Cylinder leak down test at 4%
    New plugs installed, both getting good spark. (has aftermarket CDI box)
    Carb was taken apart and was clean. Fuel needle/seat held pressure for 10 min, float set to 1 inch
    Reeds appeared to be good and sealed tight
    Float was good and main jet clean
    Low speed jet at 11/4 turns out

    I have already replaced exhaust plate gaskets with no better results. When I bough the motor, the impeller was shot, so it may have been overheated at one time...

    Some have told me lower seal may be bad. Dealer says he thinks that is unlikely. I
    s there any other way for water from cooling system to enter the cylinder?

  2. #2

    Default Re: Merc 9.9 2 stroke water ingestion lower cylinder

    Was getting too far into this engine so I ended up scraping it...

  3. #3

    Default Re: Merc 9.9 2 stroke water ingestion lower cylinder

    Hope you sold the lower unit for a good price. They are pretty desirable.

  4. #4

    Default Re: Merc 9.9 2 stroke water ingestion lower cylinder

    Quote Originally Posted by flyingscott View Post
    Hope you sold the lower unit for a good price. They are pretty desirable.
    Yes, I got $500 CAD for it without the prop

Similar Threads

  1. water leaking slowly out above my lower unit...what is happening? (1981 Merc 25hp 2 stroke)
    By aspettapernessuno in forum Mercury Mariner Outboard Forum
    Replies: 10
    Last Post: 02-17-2016, 08:27 AM
  2. Water Ingestion
    By coupleadays in forum Mercury Mariner Outboard Forum
    Replies: 0
    Last Post: 06-14-2011, 01:17 AM
  3. Merc 57 1986 water ingestion questions
    By jiggamurf in forum Mercruiser Sterndrive Archive
    Replies: 11
    Last Post: 08-12-2009, 10:44 PM
  4. 82 merc water ingestion
    By mike giard in forum Other Gas Inboard Mfgs IO and Sterndrive Questions
    Replies: 4
    Last Post: 03-06-2006, 06:51 PM
  5. Water ingestion
    By paulw in forum Archive 2002-2006
    Replies: 5
    Last Post: 06-25-2002, 07:20 AM

Posting Permissions

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