"Greg" wrote in message
...


It will not fail on a trailer. The boat needs to be pushing
water to be running hard enough to overheat.

When you measured the water pressure, was that sitting at idle, or while
running? Does the motor have a "pee hole", and if it does, can you see a
good stream of water coming out?

I am wondering if the problem isn't some factor involving the boat, like
maybe the motor is mounted too high and the pump is sucking air. That could
be a problem when the boat is up on plane, but shouldn't be a problem while
sitting idle.


I really think this is just not pumping enough water and under a load it
overloads the ability to cool. Simple huh?
You can see why I really want to swap the whole damned foot.


The first thing I would try is to remove the foot and disassemble the water
pump. Clamp on the "ear muffs" to connect the water hose and turn the water
on. The pressure from the hose should send a good stream of water into the
pump housing.

If that looks good, then the next thing I would try it to connect a hose to
the water tube that goes up into the motor. You should be able to come up
with some combination of hoses and fittings that will allow you to clamp a
hose to the water supply tube. If you want to get really fancy you could
throw a T on the faucet and connect a pressure gauge so you can see how much
pressure you are putting into the unit. Turn the hose on and see how much
water flows. If you have your engine water pressure gauge working you can
see how much hose pressure is required to get the desired engine manifold
pressure. That might tell you a lot.

You mentioned that they had to replace a broken housing. Was this a
thermostat housing? Do you have the old one? I am thinking that you might
be able to take the broken housing, modify it to add a hose barb and use it
to back flush the upper unit. If there is a blockage in the upper unit
someplace then creating a reverse flow might wash it out.

I suppose the worst thing is that you had some sort of critter get into
the cooling system when it was really small, and then grow to such a size
that it is creating a blockage and it can't wash out.

Rod

My neighbor has a motor similar to mine and I am thinking about swapping the
foot with him to cut this problerm in half but that is a lot to ask.

Greg,
That would be a quick easy thing to try. But you are right, it's a lot to ask.
In a perfect world your dealer would have one to try. I would not be happy
bringing my boat in for repair, paying good money, only to find out it wasn't
fixed.
The possibility of a blown head gasket /cracked head is there, but I would
personally eliminate the lower unit/ water pump first.2PSI doesn't sound like
much water pressure at 4000 rpms. What is the spec on it?

BR

I am wondering if the problem isn't some factor involving the boat, like
maybe the motor is mounted too high and the pump is sucking air. That could
be a problem when the boat is up on plane, but shouldn't be a problem while
sitting idle.

The pressure is always low. This is either sitting, slow speed or up on the
step. I am still using the boat. (138 hours since it started) There is no
problem if I stay under 4000 RPM. With 50 square miles of manatee zones that is
not a problem.

If that looks good, then the next thing I would try it to connect a hose to
the water tube that goes up into the motor.

I have tried pushing water up the pipe. It seemed to flow pretty good with the
thermostat cover off but I didn't want to build up much pressure and blow a
gasket so I was just going easy with the hose.

I also back flushed it from the thermostat hole down to the pipe. It seemed to
flow OK but I don't really have a reference to how good that is supposed to be.



I suppose the worst thing is that you had some sort of critter get into
the cooling system


My biggest fear is that "critter" is something the first dealer did.

The last words out of his mouth when I left it with him was "if this thing was
running a little hotter it wouldn't make oil" and some mumbled reference to
cutting off an impeller ear. I'm afraid they did something.

The next step is probably pulling the water manifold cover and looking for a
dead rat but that is going to be the dealer, not me.

2PSI doesn't sound like
much water pressure at 4000 rpms. What is the spec on it?


The best I can tell it is 16 lbs.
I had it out tonight and I start out at about 4.5 psi until the thermostat
opens and then I am back to 2 or so. I really think the water supply tube or
the manifold must be plugged. with limited flow the pump pressure will max out
at a pretty low RPM (water starts blowing by the impeller), then more RPM won't
do much for the pressure.
I am really thinking if I get back in there myself I will make a snake from a
screen door spring and snake out that pipe.

"Greg" wrote
Blown head gasket. Do a compression test.

How does that lower water pressure?

I didn't say it did.

You said:
I have an overheating problem when I go over 4000 RPM.

To which I replied:
Blown head gasket. Do a compression test.

This will come across the wrong way, but I hope you don't get it fixed for
another week or so. This is a really interesting discussion so far. :-)

This will come across the wrong way, but I hope you don't get it fixed for
another week or so. This is a really interesting discussion so far. :-)


It has been going on since October and the next time they will be taking a
swing at it is Tuesday so I think that is a safe bet.

"Greg" wrote in message
...
This will come across the wrong way, but I hope you don't get it fixed
for
another week or so. This is a really interesting discussion so far. :-)


It has been going on since October and the next time they will be taking a
swing at it is Tuesday so I think that is a safe bet.


Well, keep posting. Murphy's Law says this is bound to happen to MY outboard
at some point. If the last few years are any indication, it'll happen during
the week of August 14th, when I'll be on vacation, trying to fish for 19
hours per day.

"Greg" wrote in message
...
I have a 2002 4 stroke 60 HP Merc.


I happened to have the lower unit off of my 2000 50 Hp Mercury outboard last
night so I was able to refresh my memory on how everything in there looked.

The pump housing has a very short lip on the output that has to mate up with
a rubber hose/coupling to the upper unit. There is not much engagement in
these two pieces. I can see where a problem such as yours would occur if the
rubber coupling did not line up with the pump output. I can picture that
the lower unit would bolt up just fine with the pump output only partially
lined up with the rubber coupling. You would get some water flow but no
pressure.

I would drop the lower unit again and look closely at the rubber coupling.
If the metal lip of the pump housing was pushing against the bottom of the
coupling, instead of going inside it, you might be able to see a line where
the sharp metal pushed against the coupling.

If you are still not sure, try putting a glob of grease around the pump
output. Put it together, take it apart and inspect the grease. If the
coupling went on like it was supposed to it would have displaced all the
grease. If the grease is still there, then you know that things didn't mate
up like they were supposed to

Rod

Yup we tried that, even put some silicone grease in the sleeve to verify how
far the pump housing engages the sleeve but I think it is that kind of
problem.
It has to be a leak or an obstruction in that tube.