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.

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.


I know you have been around boats a while.
While this can be tricky to trace, basic troubleshooting should steer you to a
solution.
One thing I would ask is: Was the engine overheated?
I have seen the grommet where the water tube goes into the powerhead adapter
melt. That would limit the flow to the powerhead.
When they changed the impeller did they change all the gaskets?


BR

I don't think it ever got over 200 degrees. I have only heard the beeper a
couple times, mostly just to prove the high guage reading is real (they have
tried to tell me my guage is wrong)
If I shut it down to an idle immediately the beeper stops.
They said they pulled the lower end shroud and inspected the supply pipe and
gasket in that $300 easter egg hunt although I wouldn't bet on anything at this
point.
I watched him do the second impeller and they installed the complete kit with
the plates and grommets. The removed impeller looks brand new, as it should be
since it was, but the plate may not have been replaced the first time.
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.

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.

I have the guage in the bottom of the water manifold where they feed to the
fuel coolers and eventually out the pee hole.
Thelflex suggests that as one of the points. This is all with the boat in the
water running. It will not fail on a trailer. The boat needs to be pushing
water to be running hard enough to overheat.
With the thermostat out it acts similar at speed, overhreating around 4000, but
up to about 2000 RPM this thing won't even get hot enough to make the computer
happy (100-110 degrees, without the thermostat). It runs like a car in "limp
home mode".
I only tried that once, just to see if there reallty was TWO bad thermostats.
(I am on #3 now in the $300 hunt).
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.

"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

I guess, if you haven't already, find out what the recommended pressure is.
I located my info for Mercurys (with a "Mercury" gauge). The lowest is
"6-12psi" for 50/60/65/70 3 cyl and the highest is "15-25psi" for a lot of
engines, most all the V-6's and all #'s are at "above 5000rpm".
I'm with you---2-4 psi isn't enough. A phone call to any dealer service
dept should get you the specs. My bet is either a leak or restriction
between the pump and the block. 'Course, it could also be a blockage before
the pump. It's easy enough to change the foot which, like you said, would
confirm or eliminate "half" the potential problems.
Good luck.
LD

"Greg" wrote in message
...
I have the guage in the bottom of the water manifold where they feed to
the
fuel coolers and eventually out the pee hole.
Thelflex suggests that as one of the points. This is all with the boat in
the
water running. It will not fail on a trailer. The boat needs to be pushing
water to be running hard enough to overheat.
With the thermostat out it acts similar at speed, overhreating around
4000, but
up to about 2000 RPM this thing won't even get hot enough to make the
computer
happy (100-110 degrees, without the thermostat). It runs like a car in
"limp
home mode".
I only tried that once, just to see if there reallty was TWO bad
thermostats.
(I am on #3 now in the $300 hunt).
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.

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.