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. :-)

LD wrote:
You may have given us a clue, with the low psi. Where did you take the
reading? top of the block? before or after the thermostat? Also, what is
your water source? Are you using the clamp on "ears" or is the foot
submerged? I'm not sure of the spec for your particular motor (my 200hp 2
stroke climbs up to 10-15 psi at idle and 20-25 at 4-5000rpms) but some
motors are half that. No matter, 2-4 psi taken properly at 2000-4000rpm
sounds way too low. Assuming the impeller is correct and installed
correctly, something in the line is leaking and preventing pressure from
building.

On another note, Are the new plugs of the same heat range? A "hotter" plug
could be the culprit.
LD

"Greg" wrote in message
...

I have a 2002 4 stroke 60 HP Merc.
I took it in for the 500 hr and everything was fine before I took it in.

$437

later (a new impeller, plugs and an oil change) I have an overheating

problem

when I go over 4000 RPM.
I get Mercury involved and they say go to another dealer. $350 later (lots

of

easter egging around, a new thermostat, a housing THEY BROKE and another
impeller) and I am still overheating. I hooked up a guage and it is 4PSI

until

the thermostat opens then it is more like 2PSI. RPMs don't seem to change

it

much and whenever I get much over 3000 RPM I see the temp climbing. At

4000 it

is very hot and the beeper goes off.
I am collecting a white pasty substance around the thermostat that I think

is a

result of evaporating salt water since the flow is so low. Even when it is

all

flushed out I am still having the problem.




It's not the pressure, it's the flow.

I would be very picky in 2 areas:

1. Is there a foreign object somewhere, blocking normal flow near
the discharge of the water pump?

2. Is there a part missing in the impeller area, like a crescent
shaped filler that turns the impeller body into a pump, or a key,
set screw, or shim?

It sure seems like the trained monkeys at dealer 1 are having fun
laughing at the trained monkeys at dealer 2.

It was working before the 1-chimps got at it, right?

You should be talking lawsuit, if only you could find a real
mechanic to fix what the chimp did and write you an invoice stating
that they put the key back in your impeller shaft drive, or
retrieved and replaced the missing pump piece, whatever, perhaps
even installing a gasket upside down, or losing a set screw and not
bother finding it because "There were two, and one seemd enough"?

I had a similar problem with my oil pump. a ball bearing fell out
and into the crank mains. It ran good (!) but had no oil pressure to
speak of, so it got shut off real quick. The problem was compounded
by a defective replacement oil gague.

After a couple of go arounds, I shook the block, the ball fell out,
and once reassembled, all was well. Ask why I shook the block? I
deduced there must be a part missing from the oil pump, and it had
to be a ball bearing, and it had to be inside the crank main bearing
channel just from looking and thinking. I had to grok the oil pump,
having no manual. Who would have thought an oil pump needed two
loose ball bearings rattling around in the discharge outlet?

If you pump water through the block, it should not overheat.
Somebody diddled your pump.

Here's hoping yours is just another "Bloody chimpanzee mechanic"
story. There must be millions of them. The chimps tell the best
ones, which often involve 17 wheelers and miraculous survivals. They
never own up, even when the repo guys take their cars to pay legal
bills. It's always Somebod Yelse's fault.

Good luck.

Terry K

This thing has been apart several times and the key is there.
I agree this is probably a foreign object but nobody has been able to find it.

"Greg" wrote in message
...
I have a 2002 4 stroke 60 HP Merc.
I took it in for the 500 hr and everything was fine before I took it in.
$437
later (a new impeller, plugs and an oil change) I have an overheating
problem
when I go over 4000 RPM.
I get Mercury involved and they say go to another dealer. $350 later (lots
of
easter egging around, a new thermostat, a housing THEY BROKE and another
impeller) and I am still overheating. I hooked up a guage and it is 4PSI
until
the thermostat opens then it is more like 2PSI. RPMs don't seem to change
it
much and whenever I get much over 3000 RPM I see the temp climbing. At
4000 it
is very hot and the beeper goes off.
I am collecting a white pasty substance around the thermostat that I think
is a
result of evaporating salt water since the flow is so low. Even when it is
all
flushed out I am still having the problem.

Blown head gasket. Do a compression test.

Blown head gasket. Do a compression test.

How does that lower water pressure?

We did look at the plugs and they all seem to be burning about the same, no
water in the oil and no pulses in the water jacket. Since this pressure ends up
below 60" of water (about 2PSI) I have been able to watch this with a precision
0-80 In/H2o guage. If I had a water to combustion leak I would expect to see
the guage bumping when that cylinder fired.
We have thought about a head gasket but I don't think they checked. I will ask.
Thanks

"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.

"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.