Conference unifix::sailing

    Before you go to all of the trouble of replacing the impeller, check
    the little hole where the water squirts out of the engine head
    assembly.  It can get clogged easily and give you an indication of
    a problem where none exists.  A little piece of wire will generally
    free up any clogs.
    
    
    If you have to change the impeller, the first time is the hardest.
    I used to do it all the time.  It's really pretty easy once you know
    how to get the lower unit off.  What kind of an outboard?
    
    

    Jim,
    
    I replace the impellers in my Diesel every year and keep the old ones
    for spares.  (when they are worth keeping.)
    
    When I had the NISSAN 9 horse outboard on my other boat I changed, or
    had the impeller changed every season.  I talked with lots of
    mechanics their recommendation was it's a good idea to change them at
    least every couple of years.  I think your failure symptom sounds about
    normal.  The impellers I have worked with have been made from something
    like rubber, and they just seem to become brittle and start shedding
    impeller blades.
    
    If you have an outboard for which you can acquire a how to fix it
    manual the impeller is usually not hard to remove and replace
    yourself.  A side benefit of changing the impeller periodically is the
    piece of mind of knowing that you can get the lower end off the case.  
    
    Now you have me think.  Is it time to replace the impeller in my
    dinghy's outboard?

    
    >> What kind of an outboard?
    
    Yamaha 9.9, 4-stroke.
    
    I'll order a manual, it's supposed to take 2 days to get.  I didn't
    realize that you only get 3 years or so out of the impeller; it's 
    been 3.5 years already so maybe the impeller should be replaced
    whether or not it's the cause of the current problem.
    
    re: the little exit hole
    
    yes, that's where I meant that the water would be forced in, though
    your idea of using a wire instead might be even more effective. 
    
    

    My 7.5HP Merc would periodically stop squirting water, from salt build
    up or something.  The spray attachment from a WD40 can would fit
    perfectly.  I changed the impeller every other year--cheap insurance.
    
    Travis

    
    I tried the WD40 trick this past weekend in addition to forced water
    and fishing a wire.  It didn't help, so I suspect that the impeller
    needs to be replaced.
    
    If I'm going to do this myself I still see a major problem: the boat's
    in the water and the engine's on the boat.  I've put the engine on
    while the boat was in the water before, but I'd rather have a mechanic
    do it than try that maneuver again (getting a mechanic to make
    boat calls is another good trick).
    
    Apparently I need to either:
    
        1.  Rig up a way to work on it while it's in the water, or
        2.  Figure out a safe way to get the engine on and off (95 lbs), or
        3.  Wait for a favorable wind and sail it to a marina, and pay
    	    them to do the work.
    
    I don't see any way to accomplish (2), but suggestions will be
    appreciated.  (1) might be accomplished by lashing the (hard) dink
    between the stern of the "big" boat and the dock, positioned underneath
    the engine.  In waveless conditions this might work well, but waves
    of 6" to 12" are inevitable under even calm conditions due to wakes
    from passing boats.  I'm not sure how much clearance I have.
    
    Suggestions, please?
    
       /Jim
    

    Is it possible for you to rig up a sling attached to the end of
    your boom?  With the boom supported by one or more halyards, attached
    to the after end, you should be able to take the weight of the engine,
    and perhaps even use a halyard winch to lift it.  With close
    coordination, one person could lift the engine from the transom
    and into a waiting dinghy where a second person took just enough
    weight to ease it in.  I've used this without trouble to pull a couple of
    inboard diesels, including a 6 cylinder Perkins, in rolly anchorages.
    
    If you do the job yourself, you might want to keep a propane torch
    around to help remove any recalcitrant bolts.  Don't force anything,
    since it may not take much to shear a bolt.  Be sure to throughly
    clean all bolts, replacing any that look corroded.  Stainless and 
    aluminum make a bit of a battery in salt water.  We always coated our 
    threads with a graphite compound like NeverSeize before replacing
    them.  The bolts come back off more easily that way.

    Good luck!

Having been away for a while, I'm probably replying after you've solved 
your problem, but...

>>>   2.  Figure out a safe way to get the engine on and off (95 lbs),

With three people, it might be done relatively simply by:

A. rigging a halyard to a sling around the motor unit (operated by one
attentive but not necessarily strong person and a winch), 

B. holding it off the boat, as the halyard obviously lifts from an angle 
(this requires some special attention and a bit more strength, though 
less than that required to lift 95 lbs), 

C. releasing the mounting bolts (you, most likely.)

Plan a target area onboard (the cockpit is close by and safe) with a drop 
cloth laid out ahead of time, and just swing it inboard for the first 
step.  Second step into the dinghy could be done similarly, or using the 
boom if you want to get really elegant.

J.

    
    Here's what happened:
    
       I calculated that with the angle that the halyards make with the
       engine and the weight of the engine that it would require only
       40lbs pressure to hold it away from the boat.  I decided that this
       would be an easy 2-person operation, with the second person
       operating the winch and then helping to guide the engine onto the
       dock.
    
       When I arrived at the boat the water was mirrorlike and predicted
       to stay that way.  My complex reasoning process ran something
       like "Oh the Hell with it"... and I pulled the dinghy around the
       back of the engine and went to work.
    
       The service manual turned out to be sufficiently detailed and 
       provided important hints along the way to make the job easier;
       however, it was also WRONG.  The manual clearly explained that
       it was necessary to remove the propeller shaft and pinion gear
       because the impeller could not be removed from the top of the
       shaft, only the bottom.  After struggling with a stubborn fitting
       I was unsuccessful in removing the propeller shaft and called the
       service center for help.  Removing the propeller shaft is NOT
       necessary or, for that matter, desireable.  Hmm.
    
       Once armed with the proper procedure it was easy:
    
    		o  remove the nut which connects the gear shift rod
    		o  remove the bolts (4) which hold the lower unit in place
    		o  give the lower unit a bear hug, wiggle it side to side,
    		   and pull downward to free it from the upper unit.
    		o  the impeller assembly is then visible at the top of
    		   the lower unit... it is straightforward to remove it
    		   from the shaft.
    
        The impeller was in need of replacement, but I found it surprizing
        that it was completely ineffective.  I shrugged, replaced it, 
        cleaned/greased the innards (don't put more than a dab on the
        splines at the top of the shaft or it'll jam when you try to put
        it back... it's a machined-close fit), and put it back together.
    
        Well, it still didn't work.  By the next morning it occured to me
        that with the lower unit off I could test where the blockage was:
        above or below the impeller.  I got out my galvanized wire and
        a turkey baster filled with sea water and started experimenting.
        By the way, the second time it only took a few minutes to do what
        had taken me hours the previous day.  I discovered that yes indeed,
        there was a blockage above the impeller that had escaped my
        efforts to free it.  A chunk of salt or two had built up, and once
        they were cleared all worked properly again.  I question whether 
        the engine was decommissioned properly... I doubt it, but I also
        doubt that this is provable.
    
    I guess that the moral of the story is not to be so sure you know what
    the problem is once you've got everything disassembled.  In this case
    the impeller needed replacement anyway, but I should have checked the
    upper and lower passages the first time.
    
    It took a few tries to get the dinghy lashed securely under the engine,
    but having done so I'll say that I'm glad I didn't haul the engine out.
    It was much less work using the dinghy.
    
       /Jim