Conference vicki::boats

    Colin,
    Sounds like your pump is running dry.  Check to make sure there
    are no restrictions in the water pickup and the tubes feeding the
    pump.  Especially check the filtering screens in the lower end of
    the motor. If you've been running down at Chauncy again those 
    screens are probably full of green slime and muck.   8^)
                
    Rick

    The water pickup is wide open with no blocks...
    Also there is no screen...   Is their supposed to be??????
    It just has about 20 holes on the lower unit opening into a large
    orafice going direct to the pump...

    
    
    Sounds like you are running dry- do you flushy out the motor after
    using it? Could be your "ears" arent' lining up right.
    Check the S.S. plates- sometimes they can be mounted upside down or can
    be offset causing a restriction to water flow. If you have restricted
    flow, youre engibne is probably overhaeting too- is your temp
    alarm/shutdown operative????
    
     IFg you don't flush out an engine that has been run in Salt water
    when you put it up fior storage- I have seen all kinds of
    corrosion in water pump housing from salt sitting over the winter- 
    fire it up in the spring and the impeller grinds it's way to history.
    
     When you replace the pump again, I'd check the water pressure in the
    block-  If you have a factory service manual- check the specs.
    
      If you are running in mud/sand- the pump will pick up that junk and 
    will be history in short order. A nice shiny propellor and skeg are 
    a sure sign that you've been operating in stuff you shouldn't have.
    
    
    Dick
    
     
    
    
     

    What are the "ears" and SS plates?????
    
    I have only been running it in fresh water (quinsig) not near any
    sand or heavy weeds.   As I said this pump only had a couple of
    hours on it before it had a melt down.  The motor never seamed
    to overheat.  I am not sure if my alarm is working or not.  any
    way to test it???
    
    All I could think of is if it has a thermostat that was not opening
    then it would restrict the water flow and also the lower end would
    heat up from the raw exhaust without the water possible causing
    the plastic to melt.   This also seems strange though since it is
    submersed in water all the time while running....
    
    Maybe it was a defective pump that they sold me????   How to prove
    that I don't know. 
    
    Is there a way to check for water flow through the head???
    
    Colin
    

    
    
    Even with the thermostat closed, there is still water circulation-the 
    "tell tale" on the mercs is a small stream of water squirting out of 
    the base of the upper housing- if you don't have this stream , I would
    look for an obstructuion someplace. There is usually a pipe plug
    someplace on the powerhead that can be used to test water pressure. 
    If you have a temp gauge or water temp switch , that screws out and 
    you can screw in a gauge- these fittings are usually 1/8" NPT.
    
     The overheat switch can be either a temp switch screwed into the water
    jacket or a bimetallic switch mounted on the port side of the
    powerhead. On the older mercs, when the engine block got hot, the
    switch would open the ignition. I believe on the newer ones, it
    actuautes a lamp or a buzzer.
    
      If you don't have a manual, I suggest you get one. I would also
    suggest bringing the pump into a dealer alnong with the lower unit to
    have him look at it or install the pump.
    
     If the pump is moving any water at all- the problem is too tight a
    fit-If the pump was running that dry, you would have fried the motor.
    From what you have mentioned, it appears that the problem is not one of
    the pump running dry.
    
     Have you run the motor out of the water?-I have seen people run in
    shallow water( like coming up to a ramp or near shore), with the engine 
    tilted way up. The prop is in the water, but the water pick up is out
    of the water. THis starves the pump and eats it, but the engine is not
    run long enough to get serious overheating.
    
    
    
    
     

	I have a small 4 hp merc circa 1970 and the water impeller 
went this past sunday. It was not spitting out water like it should.
The engine got hot for a couple of minutes. It still starts so its not siezed.

	My question is should I try to fix it myself. I am a weekend tinkerer.
I have rebuilt motorcycles and done basic stuff on cars like water pumps,
carb rebuild, tuneups etc. 

	Will I need a manual or is it fairly strait foward? 

	Where is the impeller located? in the shaft or up top in the engine?

	Should I pull the head and check the cylinder?

	What will parts run? Impeller, Rings

	How much to hone if necessary?

Any good shop recommendations and estimate on cost? I live in Sturbridge and 
work in Marlboro.

	Thanks....Jim    
    
    
     

    Re .6>
    
    Jim,
    	If the manual is available, the job should be relatively easy. If you 
    don't have access to a manual you can still probalby do it but you'll have 
    to "figure as you go".
    	The impeller is usually in the lower unit. When you start getting
    things torn down you will see a tube going up to the power head. The
    pump should be attached to this tube, probably near the bottom. Start 
    taking apart whatever looks likely and you should come across star shaped 
    rubber thingy...this is the impeller.  
    	Replace it and anything else that looks bad (pump housing, gaskets
    etc.) You can probably buy a water pump rebuilding kit as a package
    for $20 or so.
    	Make sure the water passageways are clear, reassemble everything
    and test it with earmuffs or in a barrel of water.
    	If it runs and pumps water okay I'd suggest you test it under load.
    If you loose power after it warms up you probably did some damage and
    will need to pull the head to determine its extent; otherwise your home
    free.
    	I don't recommend pulling the head unless you need to. I'd rather
    spend the $20 and gamble (you could minimize this by being carefull
    with the gaskets etc.). If there is damage I wouldn't hold out much
    hope of rebuilding the power head. Aluminum alloy blocks aren't very
    rebuildable, particulalry in a 20 year old motor.I don't think the
    cylinders are sleeved but I could be wrong.
    
    Paul

	Thanks Paul,

	I don't have a manual, but I think i will give it a try. The last time 
it went I paid over $ 100 for repair and a tune Up (replace the spark plug )
and it took them more than 6 minths to get the motor back to me. Funny 
I have never had any problems with the motor, only breaks when someone else 
uses it....

	I let you know how I make out

	Jim

Jim,
	Hit one of the larger public libraries, & either check out the manual
or (I didn't say this) copy the relevant pages.  I know hte Worcester, Ma 
library has the manuals and I'm sure many of the other large libraries must
have them too.


Al

    Another water pump question?
    
    I recently bought a 1973 Sea Sprite 18' 140 I/O  4 cylinder inline
    
    It just started leaking water under the engine. seems to be dripping
    from the rear of the engine. This is leaking with the engine running or
    off.
    
    The engine runs fine.
    
    The manual says that if the water pump starts to go bad it can start
    leaking water from the engine. Does this sound like a water pump
    problem?  How does a bad water pump cause leaks? 
    
    Also according to the manual the water pump can be changed without
    pulling the engine. Has anyone replaced a water pump on one of these
    chevy engines?
    
    
    Thanks
    
    Mike
    
    
    

    Water pumps are forward of the stern so I doubt that is what leaking.
    You didn't mention which brand your power system is. If it's an old OMC
    (like mine -- 1977) they have a rubber gasket about the outdrive itself
    which could be the source of your leak. If this is the case, get a GOOD
    bilge pump to hold you out till off season for replacement of the
    gasket.

    The power system is an OMC with the black rubber gasket. From the
    repair records that came with the boat this gasket was replaced in
    1990.
    I did reseal the outside of this gasket with a good coat of marine
    sealer.
    
    As I did some more thinking about this it seems likely that the leak is
    from the seal, as the water is cold not hot and seems to be dripping
    from the top of the intermediate housing.
    
    Time to get out there and do some inspecting.
    
    Thanks
    
    Mike
    

    One more thing to check with an OMC with the rubber boot around it is
    the following:
    
    With the outdrive in the up position, look under it and you will see a
    black rubber control cable or whatever it is. It is about one quarter
    of an inch in diameter. It runs from the outdrive leg in through the
    transom in the middle of the transom plate. If it is not pushed in all
    the way so that the molded in lip is seated, it will leak. When I
    bought a 1977 OMC outdrive equipped boat the dealer didn't seat the
    cable and the first time I left it in the water overnight, I had a foot
    of water in the bilge by morning.