Today I was accelerating out of the Boca Raton, FL inlet in my 2600
Martinique and just as I came off about 10 knots, the motor made a loud
noise and there was a loss of power. I immediately put the throttle into
neutral but the motor kept running and everything seemed fine. I throttled
up slowly but when I got to approximately the same power level the same
thing happened. The noise was kind of like if you took two two large 2"x4"
pieces of wood and banged them together real hard. You could feel a but of
a shock in the deck of the boat. It almost sounded like an engine mount
moving or something but the motor seemed totally fine. I just had the motor
checked out, oil changed and they checked the oil in the outdrive for
water... everything was ok. About 6 months ago I had the props removed and
outdrive oil changed. The inner prop on the engine had siezed onto the
drive shaft and they had to cut off the hub and re-mill the prop... I'm not
sure if any of this might be related. The noise happened the last time I
was out in the ocean about 3 weeks ago after about 3 hrs of troll fishing
and I powered up to head back to port. Today I had just picked up the boat
from the marina after new bottom paint had been applied and the boat was
fully washed and waxed. After the second time this happened today I decided
to head back to port and plan to call a mechanic next week.

Any ideas wht this might be?
The boat is a 26ft Wellcraft Martinique with a single Volvo Penta 5.7 GS
motor and stainless DuoProp.

Thanks for any ideas you can post.
-Mike

On Sun, 14 Nov 2004 01:59:14 -0500, "Mike"
wrote:

Today I was accelerating out of the Boca Raton, FL inlet in my 2600
Martinique and just as I came off about 10 knots, the motor made a loud
noise and there was a loss of power. I immediately put the throttle into
neutral but the motor kept running and everything seemed fine. I throttled
up slowly but when I got to approximately the same power level the same
thing happened. The noise was kind of like if you took two two large 2"x4"
pieces of wood and banged them together real hard. You could feel a but of
a shock in the deck of the boat. It almost sounded like an engine mount
moving or something but the motor seemed totally fine. I just had the motor
checked out, oil changed and they checked the oil in the outdrive for
water... everything was ok. About 6 months ago I had the props removed and
outdrive oil changed. The inner prop on the engine had siezed onto the
drive shaft and they had to cut off the hub and re-mill the prop... I'm not
sure if any of this might be related. The noise happened the last time I
was out in the ocean about 3 weeks ago after about 3 hrs of troll fishing
and I powered up to head back to port. Today I had just picked up the boat
from the marina after new bottom paint had been applied and the boat was
fully washed and waxed. After the second time this happened today I decided
to head back to port and plan to call a mechanic next week.

Any ideas wht this might be?
The boat is a 26ft Wellcraft Martinique with a single Volvo Penta 5.7 GS
motor and stainless DuoProp.

Thanks for any ideas you can post.
-Mike

Not enough insight to be sure - so here are some ideas

Detonation - premature fast i\gnition, very damamging.
Low fuel grade - hot spot in cylinder head - too high compression.

Shaft grabbing.

Check engine oil for water - check plugs for water washed clean
appearance.

That';s all that comes to mind

Brian W

Brian,

Thanks for the feedback.

I was also wondering if this might have anything to do with the
exhaust manifolds. The engine is raw/seawater cooled and manifolds
are original on this 2000 model year boat. I understand you typically
can expect 4-5 years out of a set of risers and manifolds so I am
probably due to have them changed anyway.

The service person told me today that he didn't notice any water in
the outdrive oil and I changed the sparkplugs myself only about 2
months ago. The plugs were pretty black (may have never been changed)
and now that I think about it again, I had actually noticed the noise
once before back sometime in Jan or Feb of 2004 prior to changing the
plugs... I just didn't pay as much attention to the issue as it is my
first boat and was not as familiar with her behavior. My wife and I
actually thought maybe we had hit a piece of wood in the inlet when it
happened the first time.

I will have to run a compression test. Any ideas what compression
should be reading for the Volvo Penta 5.7 GS motor?

Thanks Again,
-Mike

Brian Whatcott wrote in message . ..
On Sun, 14 Nov 2004 01:59:14 -0500, "Mike"
wrote:

Today I was accelerating out of the Boca Raton, FL inlet in my 2600
Martinique and just as I came off about 10 knots, the motor made a loud
noise and there was a loss of power. I immediately put the throttle into
neutral but the motor kept running and everything seemed fine. I throttled
up slowly but when I got to approximately the same power level the same
thing happened. The noise was kind of like if you took two two large 2"x4"
pieces of wood and banged them together real hard. You could feel a but of
a shock in the deck of the boat. It almost sounded like an engine mount
moving or something but the motor seemed totally fine. I just had the motor
checked out, oil changed and they checked the oil in the outdrive for
water... everything was ok. About 6 months ago I had the props removed and
outdrive oil changed. The inner prop on the engine had siezed onto the
drive shaft and they had to cut off the hub and re-mill the prop... I'm not
sure if any of this might be related. The noise happened the last time I
was out in the ocean about 3 weeks ago after about 3 hrs of troll fishing
and I powered up to head back to port. Today I had just picked up the boat
from the marina after new bottom paint had been applied and the boat was
fully washed and waxed. After the second time this happened today I decided
to head back to port and plan to call a mechanic next week.

Any ideas wht this might be?
The boat is a 26ft Wellcraft Martinique with a single Volvo Penta 5.7 GS
motor and stainless DuoProp.

Thanks for any ideas you can post.
-Mike

Not enough insight to be sure - so here are some ideas

Detonation - premature fast i\gnition, very damamging.
Low fuel grade - hot spot in cylinder head - too high compression.

Shaft grabbing.

Check engine oil for water - check plugs for water washed clean
appearance.

That';s all that comes to mind

Brian W

For any four stroke, a compression under 110 psi or different by more
than +-15 psi between cylinders is reason for suspicion.

Brian W

On 15 Nov 2004 13:06:59 -0800, (Mike) wrote:

Brian,

Thanks for the feedback.

I was also wondering if this might have anything to do with the
exhaust manifolds. The engine is raw/seawater cooled and manifolds
are original on this 2000 model year boat. I understand you typically
can expect 4-5 years out of a set of risers and manifolds so I am
probably due to have them changed anyway.

The service person told me today that he didn't notice any water in
the outdrive oil and I changed the sparkplugs myself only about 2
months ago. The plugs were pretty black (may have never been changed)
and now that I think about it again, I had actually noticed the noise
once before back sometime in Jan or Feb of 2004 prior to changing the
plugs... I just didn't pay as much attention to the issue as it is my
first boat and was not as familiar with her behavior. My wife and I
actually thought maybe we had hit a piece of wood in the inlet when it
happened the first time.

I will have to run a compression test. Any ideas what compression
should be reading for the Volvo Penta 5.7 GS motor?

Thanks Again,
-Mike

Brian Whatcott wrote in message . ..
On Sun, 14 Nov 2004 01:59:14 -0500, "Mike"
wrote:

Today I was accelerating out of the Boca Raton, FL inlet in my 2600
Martinique and just as I came off about 10 knots, the motor made a loud
noise and there was a loss of power. I immediately put the throttle into
neutral but the motor kept running and everything seemed fine. I throttled
up slowly but when I got to approximately the same power level the same
thing happened. The noise was kind of like if you took two two large 2"x4"
pieces of wood and banged them together real hard. You could feel a but of
a shock in the deck of the boat. It almost sounded like an engine mount
moving or something but the motor seemed totally fine. I just had the motor
checked out, oil changed and they checked the oil in the outdrive for
water... everything was ok. About 6 months ago I had the props removed and
outdrive oil changed. The inner prop on the engine had siezed onto the
drive shaft and they had to cut off the hub and re-mill the prop... I'm not
sure if any of this might be related. The noise happened the last time I
was out in the ocean about 3 weeks ago after about 3 hrs of troll fishing
and I powered up to head back to port. Today I had just picked up the boat
from the marina after new bottom paint had been applied and the boat was
fully washed and waxed. After the second time this happened today I decided
to head back to port and plan to call a mechanic next week.

Any ideas wht this might be?
The boat is a 26ft Wellcraft Martinique with a single Volvo Penta 5.7 GS
motor and stainless DuoProp.

Thanks for any ideas you can post.
-Mike

Not enough insight to be sure - so here are some ideas

Detonation - premature fast i\gnition, very damamging.
Low fuel grade - hot spot in cylinder head - too high compression.

Shaft grabbing.

Check engine oil for water - check plugs for water washed clean
appearance.

That';s all that comes to mind

Brian W