I'm in the process of purchasing a 2002 Cruisers with Caterpiller 3126
engines. Please give me your honest opinion about these engines.
Thanks,

Al wrote in message
. ..
I'm in the process of purchasing a 2002 Cruisers with Caterpiller 3126
engines. Please give me your honest opinion about these engines.
Thanks,

First of all, they come in many flavors, meaning horsepower ratings. The
electronic 3126 is rated at 450 hp. The mechanical version is 420 hp. I
think there are also lower horsepower versions of the same engine.

I had the 420 hp versions in a 2002 Egg Harbor and had no issues or
problems, other than a bad pre-heater circuit breaker that Cat replaced.

My impressions:

They are noisy. Not exhaust noise, but loud engine noise. More so, I think,
than most diesels.
To get full power and RPM they are very sensitive to fuel condition and
flow. Keep the Racors clean.
They always ran fine - but or course there were not many hours on them.

When I was looking for a sport-fish type boat, I got all kinds of
conflicting recommendations on the 3126 (6 cylinder) versus the 3208 (8
cylinder). Half the people told me the 3126 was problem prone, and the
other half said the 3126 was a great engine and the 3208 was no good.

I have been told that the Cat 3116 *was* problematic. It was primarily used
in school buses and was not really designed for marine applications. The
3126 model was supposed to be a marine application engine, correcting the
3116 deficiencies. I don't know if this is really true or not.

Cat has stopped making the 3208 for whatever reasons.

One other general impression or opinion:

Diesel engine manufacturers are squeezing every bit of horsepower out of
smaller engines now-a-days to keep the overall boat weight down and to get
more speed, especially on sports-fish type boats where the owner wants to
make a fast run out to the fishing areas and back. As a result, the life
expectancy before overhaul or replacement is getting shorter. Naturally
aspirated diesels that were good for 10-12 thousand hours of operation are
now good for half that when equipped with turbochargers and other horsepower
increasing changes.

Sorry, I can't be of much help as I didn't put enough hours on the Egg to
develop any other impressions.

Eisboch

Al wrote in message
. ..


I'm in the process of purchasing a 2002 Cruisers with Caterpiller 3126
engines. Please give me your honest opinion about these engines.
Thanks,


One other item I forgot in the other post:

How many hours on the engines? The Cat people told me in no uncertain terms
that the engines should be serviced by Cat at 250 hours and this service was
the most important one to have done. (post break-in).

If the Cruisers you are looking at has over 250 hours, I'd verify with the
owner that the service had been done, otherwise damage can occur, according
to Cat. Have an oil analysis done also to make sure there are no developing
problems and to establish a baseline for your own records.

Eisboch

On Wed, 24 Nov 2004 22:23:34 GMT, "Eisboch"
wrote:



Al wrote in message
. ..


I'm in the process of purchasing a 2002 Cruisers with Caterpiller 3126
engines. Please give me your honest opinion about these engines.
Thanks,


One other item I forgot in the other post:

How many hours on the engines? The Cat people told me in no uncertain terms
that the engines should be serviced by Cat at 250 hours and this service was
the most important one to have done. (post break-in).

If the Cruisers you are looking at has over 250 hours, I'd verify with the
owner that the service had been done, otherwise damage can occur, according
to Cat. Have an oil analysis done also to make sure there are no developing
problems and to establish a baseline for your own records.

There's something that puzzles me about marine diesels.

I assume that these are high revolution diesels much like the one in
my truck. How do boats like that Topaz I'm looking at generate their
speed - gearbox?

Oh, and while I'm on the subject, how does a engine synchro work? I
have an idea, but I'm not sure.

Later,

Tom
-----------
"Angling may be said to be so
like the mathematics that it
can never be fully learnt..."

Izaak Walton "The Compleat Angler", 1653

Short Wave Sportfishing wrote in message
...


I assume that these are high revolution diesels much like the one in
my truck. How do boats like that Topaz I'm looking at generate their
speed - gearbox?

That and prop pitch and diameter. My Navigator engines (Volvo) are rated at
2800 RPM with a recommended cruising RPM or 2600 RPM. I can't remember the
transmission gear ratio - I think it is 2:1, but I am not sure. The props
are 30" dia. by 30 pitch.

The Egg with the 3126 Cats was also rated at about 2800 RPM WOT. Again, I
don't remember the gear box ratio, and the props were something like 25"
dia. by 28 pitch.

Many of the serious sports-fish types have "trolling valves" installed on
the transmissions that allow a certain amount of hydraulic slip that permits
the boat to troll at a lower speed. Otherwise, the only way to troll below
about 6 knots was to put one transmission in neutral and work with one
engine and even then, on some of the really high-powered boats, you can't go
slow enough.


Oh, and while I'm on the subject, how does a engine synchro work? I
have an idea, but I'm not sure.

On both the Navigator and the Egg, there is a mechanical tachometer take-off
on the main crankshaft pulley on the front of the engines. A cable, similar
to an old-fashioned speedometer cable, transfers the rotational
speed of the tach to a hydraulic controller that is connected to the
throttle of the "slave" engine.

In operation, turning the synchro on disconnects the manual throttle control
of the slave engine and the hydraulic controller takes over and adjusts the
slave engine throttle to match the master engine RPM.
Both engines are now controlled by adjusting the master engine throttle
only.

I was amazed at how well they work. Although you can "tune" by ear, on
bigger boats it is sometimes hard to detect a 20 or 30 RPM difference. When
I first got the Navigator, I used to control both throttles manually at
first and thought I was doing a great job in keeping them in sync. I
noticed one day that the starboard engine was running about 5 degrees hotter
than the port engine after a long run. The temps were still well within
normal, but, being a nerd, I started worrying about why. A friend was with
me who is far more experienced than I and noticed I didn't have the syncs
on. At his suggestion I engaged them and within 5 minutes both engine temps
were identical.

Does that help?

Eisboch


Later,

Tom
-----------
"Angling may be said to be so
like the mathematics that it
can never be fully learnt..."

Izaak Walton "The Compleat Angler", 1653

On Wed, 24 Nov 2004 23:46:29 GMT, "Eisboch"
wrote:


Short Wave Sportfishing wrote in message
.. .


I assume that these are high revolution diesels much like the one in
my truck. How do boats like that Topaz I'm looking at generate their
speed - gearbox?

That and prop pitch and diameter. My Navigator engines (Volvo) are rated at
2800 RPM with a recommended cruising RPM or 2600 RPM. I can't remember the
transmission gear ratio - I think it is 2:1, but I am not sure. The props
are 30" dia. by 30 pitch.

The Egg with the 3126 Cats was also rated at about 2800 RPM WOT. Again, I
don't remember the gear box ratio, and the props were something like 25"
dia. by 28 pitch.

Many of the serious sports-fish types have "trolling valves" installed on
the transmissions that allow a certain amount of hydraulic slip that permits
the boat to troll at a lower speed. Otherwise, the only way to troll below
about 6 knots was to put one transmission in neutral and work with one
engine and even then, on some of the really high-powered boats, you can't go
slow enough.


Oh, and while I'm on the subject, how does a engine synchro work? I
have an idea, but I'm not sure.

On both the Navigator and the Egg, there is a mechanical tachometer take-off
on the main crankshaft pulley on the front of the engines. A cable, similar
to an old-fashioned speedometer cable, transfers the rotational
speed of the tach to a hydraulic controller that is connected to the
throttle of the "slave" engine.

In operation, turning the synchro on disconnects the manual throttle control
of the slave engine and the hydraulic controller takes over and adjusts the
slave engine throttle to match the master engine RPM.
Both engines are now controlled by adjusting the master engine throttle
only.

I was amazed at how well they work. Although you can "tune" by ear, on
bigger boats it is sometimes hard to detect a 20 or 30 RPM difference. When
I first got the Navigator, I used to control both throttles manually at
first and thought I was doing a great job in keeping them in sync. I
noticed one day that the starboard engine was running about 5 degrees hotter
than the port engine after a long run. The temps were still well within
normal, but, being a nerd, I started worrying about why. A friend was with
me who is far more experienced than I and noticed I didn't have the syncs
on. At his suggestion I engaged them and within 5 minutes both engine temps
were identical.

Does that help?

Very much - that's pretty much how I thought they worked. I've worked
on three engine pulling tractors that use much the same concept - a
master and two slaves in that case. It was quite the deal - turbo
diesels. It was quite the setup.

Thanks for the info.

Later,

Tom

In article ,
Short Wave Sportfishing wrote:


On Wed, 24 Nov 2004 22:23:34 GMT, "Eisboch"
wrote:



Al wrote in message
. ..


I'm in the process of purchasing a 2002 Cruisers with Caterpiller 3126
engines. Please give me your honest opinion about these engines.
Thanks,


One other item I forgot in the other post:

How many hours on the engines? The Cat people told me in no uncertain terms
that the engines should be serviced by Cat at 250 hours and this service was
the most important one to have done. (post break-in).

If the Cruisers you are looking at has over 250 hours, I'd verify with the
owner that the service had been done, otherwise damage can occur, according
to Cat. Have an oil analysis done also to make sure there are no developing
problems and to establish a baseline for your own records.

There's something that puzzles me about marine diesels.

I assume that these are high revolution diesels much like the one in
my truck. How do boats like that Topaz I'm looking at generate their
speed - gearbox?

Yep. That and the pitch of hte prop. For some boats you have a problme
where the lowest speed you can make is in excess of 6 knots, which is a
problem for trolling. The "fix" for tha tis trolling valves that
intentionally drop the clutch pressure and allow them to slip (controlled) -
they work, but if you come off idle with them turned on, you will destroy a
gearbox in seconds. So they do require discipline.....

Oh, and while I'm on the subject, how does a engine synchro work? I
have an idea, but I'm not sure.

There are two basic systems out there...

The mechanical sync - which Glendinning is known for - works on the tach
drives. Both engine tach cables are run to the unit. WHen it is turned on,
the unit computes a difference between the two tach drive speeds, and uses
that to slew the slave throttle. until the difference is zero. It is
extremely effective and smooth, and is quite simple.

The elcetronic engines can sync electronically, since they're "fly by wire".

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