Pre purchase 2000 23 Conquest Inspection

A conversation among Whalers
JPTL
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Joined: Wed Jun 09, 2021 12:36 pm

Pre purchase 2000 23 Conquest Inspection

Postby JPTL » Wed Jun 09, 2021 12:47 pm

I may purchase a [2000--ALWAYS USE FOUR DIGITS FOR YEARS] 23 Conquest with twin Mercury OptiMax 150-HP engines, which are likely also c.2000 engines.

Tell me what problems areas I should look for in a c.2000 23 CONQUEST and its engines.

BACKSTORY: I have owned several boats in my lifetime, but I have only appreciated others' Boston Whaler boats, not having ever actually owned one myself. I'm new to this c.2000 23 CONQUEST model, and its hull.

Any advice that may be considered obvious in this forum, may not be obvious to me, so advise away.

Realizing that the expertise on this forum is in Boston Whaler boats and not Mercury outboard engines, any additional info on the Mercs would be appreciated.

EDIT: Thank you moderators, for quickly making my thread public and to Jimh for the excellent contribution to the "History of 23 Conquest" thread.
2000 Conquest 23

jimh
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Location: Michigan, Lower Peninsula
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Re: Pre purchase 2000 23 Conquest Inspection

Postby jimh » Thu Jun 10, 2021 11:15 am

JP'--I think you allude to the 2003 thread at

History of 23 Conquest
https://continuouswave.com/ubb/Forum8/HTML/000810.html

and my comments therein.

Regarding the engines: the Mercury OptiMax was a two-stroke-power-cycle engine with direct injection using a rather elaborate and unusual system that was licensed from Orbital, otherwise known as the Orbital Combustion Systems (OCS). The OCS used two pumps, one to pressurize the fuel and a second to pressurize the air, then injected the fuel-air mixture into the cylinder combustion chamber. The result was a clean-emission engine that met EPA requirements for reduction of regulated exhaust gas emissions in effect at that time, while maintaining the excellent power output and broad engine power band of a two-stroke-power-cycle engine. However, there were and remain some drawbacks.

Perhaps the most notable characteristic of the OptiMax was its sound signature: it was loud. The loud operation was due in part to the operation of the air compressor in the engine. The air compressor was actually developed from the block of a small-horsepower two-stroke engine, which was run as a compressor using a rubber serpentine belt that also turned the alternator, taking power from the main engine crankshaft. (The asymmetric load on the crankshaft bearing was a possible a cause of some trouble in high-run-time engines.) The noise signature was quite distinctive and did not have a particularly pleasant sound.

The engines you are considering, the 150-HP models, were built on a smaller 2.5-liter displacement V6 block that was itself a proven design. These smaller-displacement OptiMax engines did not have the catastrophic failure problems that became associated--much to Mercury's regret--with the larger displacement V6 engines of 200-HP or more, which became known as the "Opti-Pop" engines.

In c.2006 Mercury announced they were introducing a new variant of the OptiMax, which they called the OptiMax The Next Generation (OTNG) engines. I wrote about these new models, with the intent to discover as much as possible about what Mercury had actually changed. See

OTNG--OptiMax The Next Generation
https://continuouswave.com/ubb/Forum1/HTML/011847.html

As that article details, there was not much done to the 2.5-liter engines, other than cosmetic changes.

Overtime, Mercury ended production of the OptiMax in many horsepower ranges, until only one or maybe two models remained in certain high-power configurations, often with special high-speed gear cases instead of their standard gear case. I don't know if in 2021 there are any still in production.

Since Boston Whaler was by 2000 owned by Brunswick, they were transitioning to delivering boats with engines pre-rigged, and, of course, those engines were Mercury brand engines. However, at some point, Boston Whaler decided to drop all OptiMax engines from their pre-rigged boats, and moved to offering only four-stroke-power-cycle engines.

(Off the top of my head I don't recall the exact model year they dropped the OptiMax. I spoke informally with some sales managers at Boston Whaler about this change and inquired about the reason. Their answer was: "because no one was ordering the OptiMax engines." I interpreted this a move to simplify the manufacturing inventory ordering, so as not to have engines in inventory that were never going to be sold due to low demand.)

Because prior to c.2004 Brunswick did not have their own four-stroke-power-cycle engines, Brunswick was buying engines from Yamaha and painting them black. Boston Whaler then began to offer these Yamaha four-stroke-power-cycle engines with black paint and Mercury decals on their pre-rigged boats, until c.2004 when the Mercury VERADO arrived. The demand for four-stroke-power-cycle engines to be sold on Boston Whaler boats was inferred as a cause for Mercury to need to purchase 4,000 Yamaha F225 engine in the early 2000's.

Back to the OptiMax: as mentioned, the engine has a very complex fuel induction system. Most Mercury dealers had been selling and servicing much simpler engines that used carburetors or simple electrically control fuel metering nozzles for fuel induction. As a result, a typical old-time two-stroke-outboard-engine mechanic was probably out of his depth trying to resolve problems with the complicated OptiMax. So getting good service on an OptiMax that needed a tune-up or repair of something gone wrong in the fuel system could have been a problem.

The OptiMax also ran much better if a particular premium two-stroke oil was used. Old-school boaters who thought WALMART $4-per-gallon oil was sufficient found out that $16-per-gallon premium Mercury oil would have been a better choice.

Now all that water under the keel, if the c.2000 150-HP 2.5-liter V6 OptiMax engines start easily, idle smoothly, and run well, then you are probably going to be okay--as long as you find a local service technician who is an expert of the OptiMax. The engines are more than 20-years-old, so they have survived so far; let’s hope they have many more years to run.

In the archives of CONTINUOUSWAVE's forum, there is at least one account of the OptiMax large displacement 3.0-liter engine running reliably and powerfully for more than ten years and several thousand hours of run time.

jimh
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Re: Pre purchase 2000 23 Conquest Inspection

Postby jimh » Thu Jun 10, 2021 11:23 am

ASIDE:
JPTL wrote:Any advice that may be considered obvious in this forum, may not be obvious to me, so advise away.

My compliments on the correct spelling of the complementary verb and noun forms "advise" and "advice." Correcting the spelling of those two words is a task in editing I too-often attend to.

ivansfo
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Re: Pre purchase 2000 23 Conquest Inspection

Postby ivansfo » Sat Jun 12, 2021 2:57 pm

I'm the original [owner] of a 2001 23 Conquest with twin Mercury OptiMax 135-HP engines. The 23 CONQUEST is a sturdy boat, and I plan to keep it for a long time. I've only had to deal with these defects:

  • rusting Mercury outboard trim motor; replaced trim motors
  • tilt-trim assembly failed to hold the motor in position; replaced under warranty.
  • loose and leaky mounts for the hardtop, ostly the base plates that fasten the frame to the cabin; redid most of the original fasteners.
  • a few loose through-hull fittings; they just needed to be resealed.
  • leaking cylinder on the hydraulic steering; replaced cylinder end cap glands.
  • paint bubbling on the cabin door frame; appears to be a common problem but the defect doesn't bother me anymore.


Other items to look for which I heard about but have not experienced yet are cracks on the aluminum hardtop frame, mostly at the welds, and a leaking or corroding aluminum fuel tank.

[Were I buying a used 23 CONQUEST] I would hire a surveyor to do a leak test of the fuel tank. Replacing the fuel tank is a huge ordeal on the 23 Conquest.

JPTL
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Joined: Wed Jun 09, 2021 12:36 pm

Re: Pre purchase 2000 23 Conquest Inspection

Postby JPTL » Wed Jun 16, 2021 11:21 pm

Wow. Ask a newbie question, get spot-on, and incredibly informative answers. I guess that continuousWave will be my go-to forum for Whaler-related questions. Thank you jimh for spending the time to provide me with a concise and invaluable synopsis of one of the most important aspects of any boat - its power. Your advise (kidding) is much appreciated.
ivansfo thank you for the info. that I can have on-hand for my PPI.
Wish me luck!
JP
2000 Conquest 23