Mercruiser 6.2L engine alarm problem
 

I have a 2002 Searay 270 Sundeck with a 320 hp Mercruiser 6.2L
MPI/Bravo 3 Duoprop which has just developed an engine alarm problem.

After running 10 to 15 minutes at a cruising speed of about 3400 RPM,
the engine alarm sounds. Oil pressure, oil level, engine temperature
and outdrive lubrication levels all appear to be normal. The alarm
continues to sound until idling back and shifting into neurtral.

If I run below 3100 RPM the alarm does not go off.

I have checked the engine with a digital heat gun and can find no sign
of abnormal temperatures anywhere. The serpentine belt is properly
tightened and everything else seems normal in every way.

Does anyone have any suggestions on how to troubleshoot this problem ?

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?

Mercruiser 6.2L engine alarm problem
 

Wayne.B wrote:
On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?
Have you had to replace an impeller?

No, not yet. Why do you ask?


You really should replace an impeller every other year.

Mercruiser 6.2L engine alarm problem
 

"Wayne.B" wrote in message
...
On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?

Have you looked at the owner's manual? Sometimes a tone code is generated to
indicate the trouble area.
Jim

Mercruiser 6.2L engine alarm problem
 

you are clueless aren't you
a tone, yukyuk

"Jim" wrote in message
ink.net...

"Wayne.B" wrote in message
...
On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?

Have you looked at the owner's manual? Sometimes a tone code is generated
to indicate the trouble area.
Jim

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 16:23:40 -0400, RJSmithers
wrote:

You really should replace an impeller every other year.

The boat was taken to the Searay dealer shortly before I bought it for
the 100 hour service check. Don't know for sure but it's possible the
impeller was part of that. In any case it's my understanding that
Bravo 3 outdrives do not have an impeller in the leg like the Alphas.

I believe the Bravo 3s use an engine mounted sea water pump, not sure
it it is centrifugal or uses an impeller..

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.

Mercruiser 6.2L engine alarm problem
 

Wayne.B wrote:
On Sun, 11 Mar 2007 16:23:40 -0400, RJSmithers
wrote:

You really should replace an impeller every other year.

The boat was taken to the Searay dealer shortly before I bought it for
the 100 hour service check. Don't know for sure but it's possible the
impeller was part of that. In any case it's my understanding that
Bravo 3 outdrives do not have an impeller in the leg like the Alphas.

I believe the Bravo 3s use an engine mounted sea water pump, not sure
it it is centrifugal or uses an impeller..

They do use a engine mounted water pump, and it does have an impeller.
Every book and manual I have read suggests changing the impeller every
year or two. They are inexpensive and the damage caused by a broken
impeller is very expensive.

http://www.sailmag.com/boatworks/bw08.impeller.pdf

Mercruiser 6.2L engine alarm problem
 

I don't think so. The similarity between a 2002 merc i/o and your outboards
ends somewhere around the fact that they both use gas.

My first guess would be that he has the same alarm setup merc used for
years. A collection of sensors is tied to an alarm. Nothing to do with the
fuel control computer. If that is the case then he needs to determine is an
alarm sensor is malfunctioning or if one of his gauges is not working.
Probably safe to say he has oil pressure or he would have had some other
nasty symptoms by now. Overheating is the other possibility.

The correct test is to remove the sensor, hang it in a pot of water with a
continuity or ohm meter on it and a thermometer it and raise the temp until
it trips. Of course the shop would simply stick another sensor in and if
that didn't work you'd get charged for it anyway.

"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is
generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.

Mercruiser 6.2L engine alarm problem
 

Seems that James is clueless also.

"James" wrote in message
link.net...
I don't think so. The similarity between a 2002 merc i/o and your
outboards ends somewhere around the fact that they both use gas.

My first guess would be that he has the same alarm setup merc used for
years. A collection of sensors is tied to an alarm. Nothing to do with
the fuel control computer. If that is the case then he needs to determine
is an alarm sensor is malfunctioning or if one of his gauges is not
working. Probably safe to say he has oil pressure or he would have had
some other nasty symptoms by now. Overheating is the other possibility.

The correct test is to remove the sensor, hang it in a pot of water with a
continuity or ohm meter on it and a thermometer it and raise the temp
until it trips. Of course the shop would simply stick another sensor in
and if that didn't work you'd get charged for it anyway.

"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is
generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.

Mercruiser 6.2L engine alarm problem
 

On Mon, 12 Mar 2007 12:59:14 GMT, "James" wrote:

The correct test is to remove the sensor, hang it in a pot of water with a
continuity or ohm meter on it and a thermometer it and raise the temp until
it trips. Of course the shop would simply stick another sensor in and if
that didn't work you'd get charged for it anyway.

It's not the temperature sensor. We did a test the other day where we
unplugged it. The alarm system gives two short beeps to alert you and
then stops. Running with the temp sensor disconnected we stil got the
other alarm after several minutes of running at 3400 RPM. When I heat
gun the thermostat housing where both the temp guage sender and alarm
sensor are located, the temperature is within a few degrees of the
thermostat (160 degrees).

The owners manual says that alarm trips are recorded by the ECM.

Mercruiser 6.2L engine alarm problem
 

On Mar 12, 11:05 am, Wayne.B wrote:
On Mon, 12 Mar 2007 12:59:14 GMT, "James" wrote:
The correct test is to remove the sensor, hang it in a pot of water with a
continuity or ohm meter on it and a thermometer it and raise the temp until
it trips. Of course the shop would simply stick another sensor in and if
that didn't work you'd get charged for it anyway.

It's not the temperature sensor. We did a test the other day where we
unplugged it. The alarm system gives two short beeps to alert you and
then stops. Running with the temp sensor disconnected we stil got the
other alarm after several minutes of running at 3400 RPM. When I heat
gun the thermostat housing where both the temp guage sender and alarm
sensor are located, the temperature is within a few degrees of the
thermostat (160 degrees).

The owners manual says that alarm trips are recorded by the ECM.

Starting to sound like a trip to the dealer :-(

Mercruiser 6.2L engine alarm problem
 

"Wayne.B" wrote in message
...
I have a 2002 Searay 270 Sundeck with a 320 hp Mercruiser 6.2L
MPI/Bravo 3 Duoprop which has just developed an engine alarm problem.

After running 10 to 15 minutes at a cruising speed of about 3400 RPM,
the engine alarm sounds. Oil pressure, oil level, engine temperature
and outdrive lubrication levels all appear to be normal. The alarm
continues to sound until idling back and shifting into neurtral.

If I run below 3100 RPM the alarm does not go off.

I have checked the engine with a digital heat gun and can find no sign
of abnormal temperatures anywhere. The serpentine belt is properly
tightened and everything else seems normal in every way.

Does anyone have any suggestions on how to troubleshoot this problem ?

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?


The behavior you describe is usually associated with a low level of outdrive
lubricant in the reservoir, but you say it's normal. I would suggest having
another person aboard and having them visually inspect the level of the
reservoir while the boat is running at 3100+ RPM to see if the level has
dropped.

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 10:48:55 -0400, Wayne.B
wrote:

I have a 2002 Searay 270 Sundeck with a 320 hp Mercruiser 6.2L
MPI/Bravo 3 Duoprop which has just developed an engine alarm problem.

After running 10 to 15 minutes at a cruising speed of about 3400 RPM,
the engine alarm sounds. Oil pressure, oil level, engine temperature
and outdrive lubrication levels all appear to be normal. The alarm
continues to sound until idling back and shifting into neurtral.

If I run below 3100 RPM the alarm does not go off.

I have checked the engine with a digital heat gun and can find no sign
of abnormal temperatures anywhere. The serpentine belt is properly
tightened and everything else seems normal in every way.

Does anyone have any suggestions on how to troubleshoot this problem ?

Might be difficult without the tools. This might interest you.
http://boards.trailerboats.com/cgi-b...c;f=4;t=000248

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Here's a link that points to a code reader. Might be expensive, but
personally I find knowing what codes an ECU is storing is golden.
Due diligence required to make sure the reader suits your 6.2.
http://forums.iboats.com/bbBoard.cgi...4;gtid=1262518

--Vic

Mercruiser 6.2L engine alarm problem
 

On Mon, 12 Mar 2007 17:13:37 GMT, "RG" wrote:

The behavior you describe is usually associated with a low level of outdrive
lubricant in the reservoir, but you say it's normal. I would suggest having
another person aboard and having them visually inspect the level of the
reservoir while the boat is running at 3100+ RPM to see if the level has
dropped.

Thanks but we did that. It seemed to be fine.

Mercruiser 6.2L engine alarm problem
 

On Mon, 12 Mar 2007 13:46:10 -0600, Vic Smith
wrote:

Might be difficult without the tools. This might interest you.
http://boards.trailerboats.com/cgi-b...c;f=4;t=000248

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Here's a link that points to a code reader. Might be expensive, but
personally I find knowing what codes an ECU is storing is golden.
Due diligence required to make sure the reader suits your 6.2.
http://forums.iboats.com/bbBoard.cgi...4;gtid=1262518

=========================

Good information, thanks.

Mercruiser 6.2L engine alarm problem
 

On 12 Mar 2007 09:21:04 -0700, "jamesgangnc"
wrote:

On Mar 12, 11:05 am, Wayne.B wrote:
On Mon, 12 Mar 2007 12:59:14 GMT, "James" wrote:
The correct test is to remove the sensor, hang it in a pot of water with a
continuity or ohm meter on it and a thermometer it and raise the temp until
it trips. Of course the shop would simply stick another sensor in and if
that didn't work you'd get charged for it anyway.

It's not the temperature sensor. We did a test the other day where we
unplugged it. The alarm system gives two short beeps to alert you and
then stops. Running with the temp sensor disconnected we stil got the
other alarm after several minutes of running at 3400 RPM. When I heat
gun the thermostat housing where both the temp guage sender and alarm
sensor are located, the temperature is within a few degrees of the
thermostat (160 degrees).

The owners manual says that alarm trips are recorded by the ECM.

Starting to sound like a trip to the dealer :-(

==================================

Maybe a "platinum" dealer if I can find one.

Mercruiser 6.2L engine alarm problem
 

"Wayne.B" wrote in message
...
On Mon, 12 Mar 2007 17:13:37 GMT, "RG" wrote:

The behavior you describe is usually associated with a low level of
outdrive
lubricant in the reservoir, but you say it's normal. I would suggest
having
another person aboard and having them visually inspect the level of the
reservoir while the boat is running at 3100+ RPM to see if the level has
dropped.

Thanks but we did that. It seemed to be fine.

Well, you have a bit of a head scratcher on your hands there. Probably the
shortest route to a diagnosis would be to read any codes that may have been
thrown. Probably a dealer issue.

Mercruiser 6.2L engine alarm problem
 

I'm pretty surprised that in 2002 merc is feeding the other sending units to
the computer. For quite a while they simply controlled fuel with it. Does
sound like that might have changed. The similarity between a couple
outboards and a chevy big block i/o is still almost non-existent.

By way of credentials I built the engine in my boat. Just finished a valve
adjustment after a cam change this spring in this picture. Block is a 40
over 350 from a 3/4 ton panel truck with aluminum heads and intake. Roller
cam, lifters, and rockers. Stainless marine exhaust with Corsa cutouts.
Plus custom cooling and lowered alternator and power steering pump.

http://home.earthlink.net/~jamesgangnc/ebay/boateng.jpg


"Jim" wrote in message
nk.net...
Seems that James is clueless also.

"James" wrote in message
link.net...
I don't think so. The similarity between a 2002 merc i/o and your
outboards ends somewhere around the fact that they both use gas.

My first guess would be that he has the same alarm setup merc used for
years. A collection of sensors is tied to an alarm. Nothing to do with
the fuel control computer. If that is the case then he needs to
determine is an alarm sensor is malfunctioning or if one of his gauges is
not working. Probably safe to say he has oil pressure or he would have
had some other nasty symptoms by now. Overheating is the other
possibility.

The correct test is to remove the sensor, hang it in a pot of water with
a continuity or ohm meter on it and a thermometer it and raise the temp
until it trips. Of course the shop would simply stick another sensor in
and if that didn't work you'd get charged for it anyway.

"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is
generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.

Mercruiser 6.2L engine alarm problem
 

Very nice work James. Kudos to you. I just had a couple of thoughts though.
My recollector is getting pretty rusty, but something tells me that once the
fuel line reaches the engine, it should convert to double flared steel. I
also am wondering if it is OK to use a non metallic fuel filter inside an
enclosed engine space. I like to see rubber fuel lines double clamped, but
maybe that's just because I'm a belt/suspenders kind of person.
Jim
"James" wrote in message
k.net...
I'm pretty surprised that in 2002 merc is feeding the other sending units
to the computer. For quite a while they simply controlled fuel with it.
Does sound like that might have changed. The similarity between a couple
outboards and a chevy big block i/o is still almost non-existent.

By way of credentials I built the engine in my boat. Just finished a
valve adjustment after a cam change this spring in this picture. Block is
a 40 over 350 from a 3/4 ton panel truck with aluminum heads and intake.
Roller cam, lifters, and rockers. Stainless marine exhaust with Corsa
cutouts. Plus custom cooling and lowered alternator and power steering
pump.

http://home.earthlink.net/~jamesgangnc/ebay/boateng.jpg


"Jim" wrote in message
nk.net...
Seems that James is clueless also.

"James" wrote in message
link.net...
I don't think so. The similarity between a 2002 merc i/o and your
outboards ends somewhere around the fact that they both use gas.

My first guess would be that he has the same alarm setup merc used for
years. A collection of sensors is tied to an alarm. Nothing to do with
the fuel control computer. If that is the case then he needs to
determine is an alarm sensor is malfunctioning or if one of his gauges
is not working. Probably safe to say he has oil pressure or he would
have had some other nasty symptoms by now. Overheating is the other
possibility.

The correct test is to remove the sensor, hang it in a pot of water with
a continuity or ohm meter on it and a thermometer it and raise the temp
until it trips. Of course the shop would simply stick another sensor in
and if that didn't work you'd get charged for it anyway.

"Short Wave Sportfishing" wrote in message
...
On Sun, 11 Mar 2007 18:50:57 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 22:33:57 GMT, "James" wrote:

Have you looked at the owner's manual? Sometimes a tone code is
generated
to indicate the trouble area.
Jim

Yes, I've been through the owners manual *very* carefully, and no,
there are no tone codes.

It would be nice if they'd give you some indication but that doesn't
seem to be the case. Apparently factory service technicians can tap
into the ECM (Engine Control Module) and get more data.

My ETECS have a system which indicates a "code" - this light blinks so
many times it means this, etc.

Sadly, you still have to get to the ECM to find out which sensor or
thingymajigger is FUBAR.

I wonder if those ecm readers that NAPA and Auto Zone sells might tell
you what's what.

Mercruiser 6.2L engine alarm problem
 

"Jim" wrote in message
link.net...

Very nice work James. Kudos to you. I just had a couple of thoughts
though. My recollector is getting pretty rusty, but something tells me
that once the fuel line reaches the engine, it should convert to double
flared steel. I also am wondering if it is OK to use a non metallic fuel
filter inside an enclosed engine space. I like to see rubber fuel lines
double clamped, but maybe that's just because I'm a belt/suspenders kind
of person.
Jim


"James" wrote in message
k.net...

By way of credentials I built the engine in my boat. Just finished a
valve adjustment after a cam change this spring in this picture. Block
is a 40 over 350 from a 3/4 ton panel truck with aluminum heads and
intake. Roller cam, lifters, and rockers. Stainless marine exhaust with
Corsa cutouts. Plus custom cooling and lowered alternator and power
steering pump.

http://home.earthlink.net/~jamesgangnc/ebay/boateng.jpg



I am also curious about something. What's that yellow colored (appears to
be plastic) tubing that runs from the carb, down below the fuel filter and
down someplace for? Is that the float overflow?

Eisboch

Mercruiser 6.2L engine alarm problem
 

"Eisboch" wrote in message
. ..

"Jim" wrote in message
link.net...

Very nice work James. Kudos to you. I just had a couple of thoughts
though. My recollector is getting pretty rusty, but something tells me
that once the fuel line reaches the engine, it should convert to double
flared steel. I also am wondering if it is OK to use a non metallic fuel
filter inside an enclosed engine space. I like to see rubber fuel lines
double clamped, but maybe that's just because I'm a belt/suspenders kind
of person.
Jim


"James" wrote in message
k.net...

By way of credentials I built the engine in my boat. Just finished a
valve adjustment after a cam change this spring in this picture. Block
is a 40 over 350 from a 3/4 ton panel truck with aluminum heads and
intake. Roller cam, lifters, and rockers. Stainless marine exhaust with
Corsa cutouts. Plus custom cooling and lowered alternator and power
steering pump.

http://home.earthlink.net/~jamesgangnc/ebay/boateng.jpg



I am also curious about something. What's that yellow colored (appears to
be plastic) tubing that runs from the carb, down below the fuel filter and
down someplace for? Is that the float overflow?

Eisboch

I'm guessing that it is there to contain the fuel if one of the fuel pump
diaphragms rupture.
Jim

Mercruiser 6.2L engine alarm problem
 

You're right, that is a vent tube from the back side of the fuel pump
to a vacuum port on the carb. If the fuel pump broke the gas would go
up that tube to the carb instead of leaking into the bilge. If you
look close you can see the fuel pump below the spin on fuel filter.
That's actually the original merc setup even though the fuel pump and
carb are both holley now.

You're also right about the fuel line, it is all rubber, I don't have
any metal line. But it is double walled marine line and I could not
find that any code that said it had to be metal somewhere, just that
it either had to be metal or it had to be double walled rubber. I
can't argue that metal would be safer. The non-metal filter is also
marine but I agree it doesn't seem like it should be. I had some
water in the fuel tank troubles some years back and I put that in to
keep an eye on it but I probably should take it out now. On the other
hand I'm always tinkering so I can keep a pretty good eye out for any
signs of impending trouble. And it's just a bowrider lake boat so
we're not really "serious" boaters ;-)

On Mar 13, 6:33 pm, "Eisboch" wrote:
"Jim" wrote in message

link.net...





Very nice work James. Kudos to you. I just had a couple of thoughts
though. My recollector is getting pretty rusty, but something tells me
that once the fuel line reaches the engine, it should convert to double
flared steel. I also am wondering if it is OK to use a non metallic fuel
filter inside an enclosed engine space. I like to see rubber fuel lines
double clamped, but maybe that's just because I'm a belt/suspenders kind
of person.
Jim
"James" wrote in message
nk.net...
By way of credentials I built the engine in my boat. Just finished a
valve adjustment after a cam change this spring in this picture. Block
is a 40 over 350 from a 3/4 ton panel truck with aluminum heads and
intake. Roller cam, lifters, and rockers. Stainless marine exhaust with
Corsa cutouts. Plus custom cooling and lowered alternator and power
steering pump.

http://home.earthlink.net/~jamesgangnc/ebay/boateng.jpg

I am also curious about something. What's that yellow colored (appears to
be plastic) tubing that runs from the carb, down below the fuel filter and
down someplace for? Is that the float overflow?

Eisboch- Hide quoted text -

- Show quoted text -

Mercruiser 6.2L engine alarm problem
 

On Wed, 14 Mar 2007 11:50:49 -0400,
wrote:

Possibility of bits of rubber from failed old pump in the cooling
system....

Possible if the previous owner had an impeller give out, or this one
is getting ready to go. At this point I may go ahead and replace the
impeller on general principles. All of the other easy stuff has
already been checked as far as I can tell.

Mercruiser 6.2L engine alarm problem
 

"Wayne.B" wrote in message
...
On Wed, 14 Mar 2007 11:50:49 -0400,
wrote:

Possibility of bits of rubber from failed old pump in the cooling
system....

Possible if the previous owner had an impeller give out, or this one
is getting ready to go. At this point I may go ahead and replace the
impeller on general principles. All of the other easy stuff has
already been checked as far as I can tell.


But if the engine checked out with a heat gun as you say, confirming a
normal reading on the helm temp gauge, it wouldn't seem to be an overheat
problem caused by impeller bits or any other cooling system malfunction.

Mercruiser 6.2L engine alarm problem
 

On Mar 14, 4:58 pm, Wayne.B wrote:
On Wed, 14 Mar 2007 11:50:49 -0400,

wrote:
Possibility of bits of rubber from failed old pump in the cooling
system....

Possible if the previous owner had an impeller give out, or this one
is getting ready to go. At this point I may go ahead and replace the
impeller on general principles. All of the other easy stuff has
already been checked as far as I can tell.


wayne, Here's a situation I was talking with a guy jsut today. And
even though a Mercury outboard it still makes sense. right after he
got his bass boat with the 200 hp outboard, the first thing he did was
pull the lower and inspect the impeller. Yeah, he said, " it was
starting to crack"
So he got an aftermarket impeller kit, and installed it. fine.

He took it out, and all was well till he nailed it, and in just a few
secondes an alarm was going off. he killed the engine, and looked
stuff over. didn't see any problems, and fired ti back up and took off
at slow speed all was well, till he nailed it again, in about the same
amount of time, the alarm went off. he idled it back down, the alarm
went silent and he cruised easy back to the dock.

He thought there might have been something really freaky, so he took
it to a Merc. dealer and told them the situation. The mechanic asked
him to repeat the story. about changing the impeller. Then the
mechanic said "Where'd you get the impeller?" the guy told him, and
the mechanic said, "thats your problem." They split the lower again
and took the impeller back out and it looked fine. just like new.
which it was.

BUT! the mechanic told him that the aftermarket impellers arn't the
same composite of rubber and are softer, so that at high RPM's, the
vanes were actually folding back and not brushing the pump housing,
thus the water flow dropped like a rock. The mechanic installed an OE
impeller, and told him to take it back out.

The guy took it back out and nailed it, and all was fine since.

I don't knwo if this is fit for your application, but I thought I'd
pass it along, seeing you just got the boat.

Mercruiser 6.2L engine alarm problem
 

On Wed, 14 Mar 2007 22:31:17 GMT, "RG" wrote:

But if the engine checked out with a heat gun as you say, confirming a
normal reading on the helm temp gauge, it wouldn't seem to be an overheat
problem caused by impeller bits or any other cooling system malfunction.

Yes. Changing the impeller is probably a good thing to do but I'm
going to be surprised if it actually fixes the problem. I had the
boat out for an hour at lunch time today, never running over 1400 RPM
or so since I was in the local canals. No alarms of course.

The closest Mercruiser mechanic has a new ECM cable on order, should
be in next week. Hopefully there is a record of the alarm trips in
there.

Mercruiser 6.2L engine alarm problem
 

On Sun, 11 Mar 2007 15:34:44 -0400, Wayne.B
wrote:

On Sun, 11 Mar 2007 15:08:26 -0400, Gene Kearns
wrote:

Is there any diagnostic equipment or process available to find out
exactly which sensor is being tripped ?

Have you had to replace an impeller?

No, not yet. Why do you ask?


Wayne, be sure and open the outdrive lube bottle and look in. The stuff
will stick to the insides of the bottle and appear to be up to level when
it's not. This happened to me and had me going crazy wondering where the
alarm was coming from.
--
***** Hope your day is better than decent! *****

John H