Mercruiser 6.2L Engine Alarm Problem - Part II (and conclusion)
 

Some of you may recall that I posted back at the beginning of March
that I was having an engine alarm problem with my 6.2L MPI Bravo 3.

After warming up, the alarm would sound at anything over 3,000 RPMs
and the rev limiter would kick in to slow down the engine. All panel
guages were reading normally, oil level and outdrive level were
normal, and a survey of the engine with a digital heat gun showed no
temperature abnormalities.

My neighbor who has a fair amount of engine expertise tried
disconnecting several different sensors but nothing helped.

The next step was to contact a local mechanic who is Mercruiser
certified. He showed up with his digital diagnostic instruments and
could find no record of tripped alarms. The only abnormality he saw
was a somewhat low reading on raw water pressure. We had already
tried disconnecting that sensor but decided to go ahead and replace
the raw water impeller. It turned out that not only was the impeller
scuffed up but also the internal pump housing so we replaced the
entire pump. Still no joy, same old alarm condition, no read out on
the Mercruiser instrumentation, but raw water pressure was now in the
normal range. Several calls by the mechanic later, several
conversations with Mercruiser, many more sea trials, another weekend,
and we were still no further along. Meanwhile the ECM had been
swapped out with one known to be good, the alternator checked, and
several more sensor swaps were made.

This morning the mechanic came back with one of his colleagues, a Dell
laptop computer with Mercruiser diagnostic software, interface cables,
etc. The laptop showed a low oil pressure reading even though the
panel guage was reading good pressure, and the Mercruiser diagnostic
box showed no oil pressure issues. Even with the low oil pressure
reading, the laptop software was still not indicating an alarm
condition although the alarm horn was howling, and the ECM rev limiter
was engaged. As luck would have it they had a spare oil pressure
sensor with them (the one that feeds the ECM, not the panel guage),
and swapped it out.

Voilla, no more engine alarms, $1200 and 3 or 4 weeks later.

Strange things these computerized engines, it must be running MS Vista
or have a virus. :-)

The mechanics say they have been running into a lot of sensor issues
with the 6.2L engines but it looks like the Mercruiser diagnostic
tools have a few bugs also, or there may be some issues with the way
the ECM is reporting problems (or not).

Mercruiser 6.2L Engine Alarm Problem - Part II (and conclusion)
 

Very interesting. Thanks for the update, Wayne.


On Sat, 14 Apr 2007 18:02:32 -0400, Wayne.B
wrote:

Some of you may recall that I posted back at the beginning of March
that I was having an engine alarm problem with my 6.2L MPI Bravo 3.

After warming up, the alarm would sound at anything over 3,000 RPMs
and the rev limiter would kick in to slow down the engine. All panel
guages were reading normally, oil level and outdrive level were
normal, and a survey of the engine with a digital heat gun showed no
temperature abnormalities.

My neighbor who has a fair amount of engine expertise tried
disconnecting several different sensors but nothing helped.

The next step was to contact a local mechanic who is Mercruiser
certified. He showed up with his digital diagnostic instruments and
could find no record of tripped alarms. The only abnormality he saw
was a somewhat low reading on raw water pressure. We had already
tried disconnecting that sensor but decided to go ahead and replace
the raw water impeller. It turned out that not only was the impeller
scuffed up but also the internal pump housing so we replaced the
entire pump. Still no joy, same old alarm condition, no read out on
the Mercruiser instrumentation, but raw water pressure was now in the
normal range. Several calls by the mechanic later, several
conversations with Mercruiser, many more sea trials, another weekend,
and we were still no further along. Meanwhile the ECM had been
swapped out with one known to be good, the alternator checked, and
several more sensor swaps were made.

This morning the mechanic came back with one of his colleagues, a Dell
laptop computer with Mercruiser diagnostic software, interface cables,
etc. The laptop showed a low oil pressure reading even though the
panel guage was reading good pressure, and the Mercruiser diagnostic
box showed no oil pressure issues. Even with the low oil pressure
reading, the laptop software was still not indicating an alarm
condition although the alarm horn was howling, and the ECM rev limiter
was engaged. As luck would have it they had a spare oil pressure
sensor with them (the one that feeds the ECM, not the panel guage),
and swapped it out.

Voilla, no more engine alarms, $1200 and 3 or 4 weeks later.

Strange things these computerized engines, it must be running MS Vista
or have a virus. :-)

The mechanics say they have been running into a lot of sensor issues
with the 6.2L engines but it looks like the Mercruiser diagnostic
tools have a few bugs also, or there may be some issues with the way
the ECM is reporting problems (or not).

--
*****Have a Spectacular Day!*****

John H

Mercruiser 6.2L Engine Alarm Problem - Part II (and conclusion)
 

I have a simular issue and still not fix. I have a 5.0 and the alarm
sound when I hit 3000 and will sound until I get to 3500-3700 (max
cruising speed for me). All gages read fine. The drive oil is just
fine. I replaced the oil alarm senson and temp sensor. I even
disconnected the drive oil temp. Same issue.

On one arm, I am quite concerned, on the other, I am just plain
annoyed. I am debating whether or not to just cut the wire to the
alarm speaker and call it quits.

What do you all think?

-Kevin Klasmeier

Wayne.B wrote:
Some of you may recall that I posted back at the beginning of March
that I was having an engine alarm problem with my 6.2L MPI Bravo 3.

After warming up, the alarm would sound at anything over 3,000 RPMs
and the rev limiter would kick in to slow down the engine. All panel
guages were reading normally, oil level and outdrive level were
normal, and a survey of the engine with a digital heat gun showed no
temperature abnormalities.

My neighbor who has a fair amount of engine expertise tried
disconnecting several different sensors but nothing helped.

The next step was to contact a local mechanic who is Mercruiser
certified. He showed up with his digital diagnostic instruments and
could find no record of tripped alarms. The only abnormality he saw
was a somewhat low reading on raw water pressure. We had already
tried disconnecting that sensor but decided to go ahead and replace
the raw water impeller. It turned out that not only was the impeller
scuffed up but also the internal pump housing so we replaced the
entire pump. Still no joy, same old alarm condition, no read out on
the Mercruiser instrumentation, but raw water pressure was now in the
normal range. Several calls by the mechanic later, several
conversations with Mercruiser, many more sea trials, another weekend,
and we were still no further along. Meanwhile the ECM had been
swapped out with one known to be good, the alternator checked, and
several more sensor swaps were made.

This morning the mechanic came back with one of his colleagues, a Dell
laptop computer with Mercruiser diagnostic software, interface cables,
etc. The laptop showed a low oil pressure reading even though the
panel guage was reading good pressure, and the Mercruiser diagnostic
box showed no oil pressure issues. Even with the low oil pressure
reading, the laptop software was still not indicating an alarm
condition although the alarm horn was howling, and the ECM rev limiter
was engaged. As luck would have it they had a spare oil pressure
sensor with them (the one that feeds the ECM, not the panel guage),
and swapped it out.

Voilla, no more engine alarms, $1200 and 3 or 4 weeks later.

Strange things these computerized engines, it must be running MS Vista
or have a virus. :-)

The mechanics say they have been running into a lot of sensor issues
with the 6.2L engines but it looks like the Mercruiser diagnostic
tools have a few bugs also, or there may be some issues with the way
the ECM is reporting problems (or not).

Mercruiser 6.2L Engine Alarm Problem - Part II (and conclusion)
 

On May 7, 9:51 pm, kklasmei wrote:
I have a simular issue and still not fix. I have a 5.0 and the alarm
sound when I hit 3000 and will sound until I get to 3500-3700 (max
cruising speed for me). All gages read fine. The drive oilis just
fine. I replaced theoilalarm senson and temp sensor. I even
disconnected the driveoiltemp. Same issue.

On one arm, I am quite concerned, on the other, I am just plain
annoyed. I am debating whether or not to just cut the wire to the
alarm speaker and call it quits.

What do you all think?

-Kevin Klasmeier



Wayne.B wrote:
Some of you may recall that I posted back at the beginning of March
that I was having an engine alarm problem with my 6.2L MPI Bravo 3.

After warming up, the alarm would sound at anything over 3,000 RPMs
and the rev limiter would kick in to slow down the engine. All panel
guages were reading normally,oillevel and outdrive level were
normal, and a survey of the engine with a digital heat gun showed no
temperature abnormalities.

My neighbor who has a fair amount of engine expertise tried
disconnecting several different sensors but nothing helped.

The next step was to contact a local mechanic who isMercruiser
certified. He showed up with his digital diagnostic instruments and
could find no record of tripped alarms. The only abnormality he saw
was a somewhat low reading on raw waterpressure. We had already
tried disconnecting that sensor but decided to go ahead and replace
the raw water impeller. It turned out that not only was the impeller
scuffed up but also the internal pump housing so we replaced the
entire pump. Still no joy, same old alarm condition, no read out on
theMercruiserinstrumentation, but raw waterpressurewas now in the
normal range. Several calls by the mechanic later, several
conversations withMercruiser, many more sea trials, another weekend,
and we were still no further along. Meanwhile the ECM had been
swapped out with one known to be good, the alternator checked, and
several more sensor swaps were made.

This morning the mechanic came back with one of his colleagues, a Dell
laptop computer withMercruiserdiagnostic software, interface cables,
etc. The laptop showed a lowoilpressurereading even though the
panel guage was reading goodpressure, and theMercruiserdiagnostic
box showed nooilpressureissues. Even with the lowoilpressure
reading, the laptop software was still not indicating an alarm
condition although the alarm horn was howling, and the ECM rev limiter
was engaged. As luck would have it they had a spareoilpressure
sensor with them (the one that feeds the ECM, not the panel guage),
and swapped it out.

Voilla, no more engine alarms, $1200 and 3 or 4 weeks later.

Strange things these computerized engines, it must be running MS Vista
or have a virus. :-)

The mechanics say they have been running into a lot of sensor issues
with the 6.2L engines but it looks like theMercruiserdiagnostic
tools have a few bugs also, or there may be some issues with the way
the ECM is reporting problems (or not).- Hide quoted text -

- Show quoted text -

You have company! I have a Mercruiser 5.0 EFI installed in a Sea Ray
Sundeck 210. I have the same problem. Above 3000 RPM the alarm kicks
in. Very ANNOYING!

Last time out, I dropped it down to idle, kept it running and stuck my
head in behind the helm. I noticed there was more than one alarm
speaker. In turn, I held my thumb over each one until the sound
stopped. I noticed the OFFENDING beeper is connected to the oil
pressure gauge. I've kept close tabs on the oil pressure gauge and it
runs at 40 a little below 3000 RPM and gets up to 60 at higher RPM.
It looks like we have plenty of pressure. And, she runs smooth as a
purring kitten except when the cat tail gets caught in the meat
grinder and the beeping begins.

I'll tell you this about this design, it certainly gets your attention
when it thinks something is wrong.

I'd like to avoid multiple fruitless mechanic visits and get this
resolved efficiently.