Welcome Guest - Sign Up today
Welcome Guest - Sign Up today

Announcement

Collapse

Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
http://forums.iboats.com/forum-rules-guidelines-405/
See more
See less

Looking at a 1990 Mercury 100 HP Outboard.

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Looking at a 1990 Mercury 100 HP Outboard.

    Guys - A search for topics only brought me more questions.I'm interested in a 1994 Larson 18ft Bowrider with a 1990 Mercury 100HP outboard on it. Not sure yet how or what happened to the '94 outboard that I would assume was originally on it.Is there anything particularly bad (or good) about this motor? My last 1990 outboard, which was a 1990 90HP Force, was a POS so I'd like to avoid those kinds of quality issues. Now I know that for 1990 Force and Merc's were not together yet, so there's hopefully no comparison.I read about Mercury only putting gas to 1/2 the cylinders (on 4 cyl motores) during these years at certain RPMs...would a 3 cyl 100HP have the same technology (and problems), or is this a pretty decent outboard by reputation?I'll of course be doing a compression check, pressure testing the Lower unit seals, etc.Thanks!!!
    My Boat:
    1978 Glastron Carlson CVZ-18
    Project Thread - http://forums.iboats.com/showthread.php?t=357939

    1986 Bayliner Capri 1600 - SOLD
    Project Thread - http://forums.iboats.com/showthread.php?t=338265

  • #2
    Re: Looking at a 1990 Mercury 100 HP Outboard.

    would a 3 cyl 100HP have the same technology
    Who makes one?These engines are known as '2+2'. They run the bottom 2 cylinders so lean that they don't fire (below about 1800revs), but still provide engough fuel to lub the nessecary parts. They still make the engines, and yes, IMHO they are good engines, but like all engines are only really as good as the maintenance performed on them.Chris.........
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    The world takes on a whole new perspective when viewed from 100 below.
    1972 Bertram Bahia Mar 20
    2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
    (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


    Comment


    • #3
      Re: Looking at a 1990 Mercury 100 HP Outboard.

      Those engines are good engines. I ran one commercially for about 4 years and had no problems at all with it. They run exactly as Chris said. The 3cyl engines run on all three all the time.Good Luck.Butch

      Comment


      • #4
        Re: Looking at a 1990 Mercury 100 HP Outboard.

        Would anyone be able to tell me the correct compression for this motor?Going to look at it on Tuesday.
        My Boat:
        1978 Glastron Carlson CVZ-18
        Project Thread - http://forums.iboats.com/showthread.php?t=357939

        1986 Bayliner Capri 1600 - SOLD
        Project Thread - http://forums.iboats.com/showthread.php?t=338265

        Comment


        • #5
          Re: Looking at a 1990 Mercury 100 HP Outboard.

          Guys - Does anyone know the correct compression for this engine? I'm looking at it tomorrow!Thanks!
          My Boat:
          1978 Glastron Carlson CVZ-18
          Project Thread - http://forums.iboats.com/showthread.php?t=357939

          1986 Bayliner Capri 1600 - SOLD
          Project Thread - http://forums.iboats.com/showthread.php?t=338265

          Comment


          • #6
            Sign up today
            Re: Looking at a 1990 Mercury 100 HP Outboard.

            The correct compression readings will be ones from a known accurate gage, and will not vary more than about 5 psi from each other. The actual value is not as critical a factor as the variance between cyliders.Any more than 5psi variance and I wouldn't touch it. And I'm sure you'll hear it from others on the forum, but a leakdown test is a much better determiner than compression readings. However, in the absence of a leakdown test, having good compression readings is at least something!BTW the 2-4 cyl stepping thing is a bit quirky, if you're going to use the boat for wakeboarding you won't like it. The 2-to-4 switch is usually made at about the same speed you'd like to board at. If you're just fishing with it, it wouldn't be as much of a factor.Be sure you run it, preferably on a boat so you can see how it idles in gear and runs out at speed. Running in the driveway on a flusher will tell you little about the motor, so be wary if that's all you can do to evaluate it. These 4's run quite fast out of the water too, due to the extra-lean condition in 2 cyls.Quite frankly, I'd prefer an Inline Six but that's just me!G'luck and let us know how it turns out.......ed

            Comment

            Working...
            X