• If this is your first visit to the iboats.com Boating Forums, be sure to check out the FAQ. To post a question or comment, begin by signing up. To start viewing messages, select the forum that you want to visit from the selection below.


Announcement

Announcement Module
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.

Below are some additional forum policies in hopes of all iboats members will follow, Thank you.

1. Please do not reply to old topics or hijack existing topics. Old topics of a technical nature are like a library book, Please do not write in them.

2. Old topics should be considered archives and used for reference only. Please do not reply to them.

3. Do not take over someone elseís topic (aka hijack) with your own question, even if it is similar. If you have a question that has not been covered to your satisfaction in the archives, it is always best to start a new topic of your own.

4. If you have a question for the original poster (OP) and the topic is over 30 days old, send the OP a PM, he may not even visit the forums any longer, or may not notice your question in the old topic.

5. By starting your own topic, you will receive the maximum number of views by forum helpers that may not even notice your question when itís posted at the end of someone elseís topic. And those answers will be specific to your particular issue.

6. Please do not post to topics that have been inactive for more than 3 months unless you are the original poster. We have very active forums and any topic that remains inactive for that long should be considered "dead". It is especially confusing when there is an entirely new question posted to an old topic.

7. Posting at the end of any topic is considered to be hijacking the original posters topic which in turn subjects the topic to be closed if it continues to happen thus not making it fair to the original poster in the future had for some reason he/she needed to return for additional information or provide an update of the problem solved which is always welcomed within a reasonable amount of time frame.

8. Please note that you should see a red banner pop up near the bottom of each inactive topic asking you not to reply to old topics. The Red banner will read: 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.

Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • 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.........
    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 1 Gen II (0W829301)
    **
    Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
    **
    Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/

    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
            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