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Author Topic:   OptiMax G2--The Globe Motors

jimh posted 02-17-2007 10:48 AM ET (US)
Just this week at the nearly empty Detroit Boat Show--where I was literally often the only person in an exhibit space--I stopped to chat with the four salesmen at the Bass Pro Shop exhibit. They were nice enough to help me get the cowling off a new Mercury OptiMax G2 90-HP motor. Here are my impressions:
First of all, the new graphics with the globe logo are very good. They immediately allow you to identify the OptiMax motor from other Mercury products. In the recent past it seemed like Mercury was embarrassed about their motor model names and hid them in very small logotypes visible only from the interior of the boat. All their motors had similar black cowlings with just MERCURY on the side, leaving you no way to tell what sort of motor it was. Now you can spot an OptiMax G2 from the cowling decals. Also, the designator OptiMax The Next Generation (OTNG) seems to have fallen aside, so we'll just call these OptiMax G2 motors or OptiMax Globe motors.
To look inside the first thing you need, of course, is to remove the cowling. Again, I am glad to say, Mercury has drastically improved their product. The cowling latch on the OptiMax G2 is at the rear. It released to the open position with a nice feel and sound. (This immediately gave me a much better feeling about the motor. The last time I tried to look under an OptiMax cowling I practically had to pry the latches loose and the cowling was very reluctant to move.) Next, the salesman and I hunted around for a minute or two for the front cowling release. But there was none. Eventually we figured out the cowling comes off by raising the rear, cocking it a bit, and sliding it forward. This disengages the forward latch mechanism, and then you lift the cowling off the motor. The cowling is a plastic molding that has moderate weight. The black color is molded into the material, so it should be quite durable. We set the cowling aside and I gave the motor a close look.
The top of the motor and the starboard side have two plastic panels covering them. These are retained with press-on rubber grommets that fit over mounting posts. They came off without much fuss, and the engine's configuration was revealed. The salesman was starting to look at me with a bit of suspicion, perhaps thinking at this point maybe he had made a mistake letting me take the cowling off.
The top cover is a shroud that covers the belt and pulleys that connect the flywheel, the alternator, the air compressor, and the belt tensioner. There is some step-up in the pulley ratio, so when the engine is spinning the flywheel at 6,000-RPM the alternator will be whizzing around even faster. The belt tensioner pulley must spin over 10,000-RPM to keep pace. The business end of the starter motor is under the shroud. It looks like a nice compact starter unit.
The starboard side cover conceals electrical connectors and components.
I like to look at an engine and see if I can figure out what all the wires and hoses are doing. On the OptiMax this is a challenge. There are a lot of wires and hoses.
The first things I looked for were the spark plugs. The upper two cylinders have plugs which are easy to see and reach. The bottom cylinder has a plug that is well below the level of the mid-section shroud. Getting a wrench on that plug will be a challenge. You may need to remove the midsection shroud to reach it. There is not much room to back the plug out, as a hose or wiring harness lies right atop the plug. The plugs have separate ignition coils. The three coils are located nearby, connected to the plugs with about 8-inches of high-tension wire. This is the old-fashioned approach to ignition and spark plugs. I would not call it "next generation." Modern engines have a coil-on-plug design, like Mercury used in the Verado. For some reason two-stroke engines all seem to have separate coils.
Next I found the six injectors. Yes, six injectors even though this is only a three-cylinder engine. There are separate air injectors and fuel injectors. They form quite a complex assembly atop each cylinder which has both a pressurized fuel rail and a pressurized air rail. There are several valve stems with Schraeder valves; I guessed these must be used for bleeding the system or for attaching diagnostic gauges. The fuel and air rails have hoses coming and going. The six injectors all have an electrical wiring harnesses attached to them with connectors. And there are the spark plugs. So each cylinder has quite a collection of wires and hoses associated with it.
Since this is a two stroke engine, there is also an oil pump, a distribution manifold, and a spaghetti of hoses carrying oil to injections points in the engine block. This pump looks like it is operated electrically.
The fuel system has a very big vapor separator and filter assembly. It appears to be a metal casting. The shape is quite odd. It looks like it was custom molded to fit someplace else. In the OptiMax G2 this assembly is just bolted on the port side of the engine, and all manner of hoses come and go from it at strange places and odd angles. It does not look like it was designed to fit into this particular engine or the space available for it.
The electrical system is mainly on the starboard side. It looks like the relays for the tilt and trim system are bolted to the engine block quite far below the level of the midsection shroud. It was hard to see them, and impossible to reach them. You would have to remove the midsection shroud to get to them. That is not a big problem, but what worried me more was the low position in the midsection. I think it is inevitable that water gets inside the cowling once in a while. With all of those electrical components mounted so low, I have a concern with them getting soaked in water. The relays look like they are sealed and potted in a plastic assembly, but it never seems like a good idea to put electrical components low in the engine cowling.
The OptiMax looks like a motor that will need a professional mechanic to perform work on it. Even a usual owner activity like changing a spark plug is going to be a challenge. The presence of so many valves and ports in the fuel systems seems like an indication that some specialized equipment may be needed to work on it, too.
When I compare the OptiMax G2 to my old classic two-stroke, I see many new components under the cowling that I don't have on the old engine:
--separate alternator with belt drive and belt tensioner
--separate air compressor
--large fuel-vapor separator filter
--complex pressurized fuel and air rails
--separate oil pump and oil distribution system
It is no wonder that these OptiMax engines are large--they have many more components under their cowlings than a classic two-stroke. I guess that is why this 90-HP motor is so much bigger than an old 90-HP Yamaha two-stroke. This 90-HP is about the same size as the classic Mercury 2.5-liter 200-HP engine.
My general impression of the new 90-HP OptiMax G2 is that the cowling is much improved, both in appearance and in its mechanics. However, under the cowling I did not see much evidence of a change that would reflect a "new generation" of engine. The engine layout still seems to be a confusing mass of hoses and wires which connect components that do not look like they were designed to fit into specific spaces. In comparison, the new Mercury FourStroke (or Veradito) motors appear better designed to fit all components together in a efficient manner.

sosmerc posted 02-17-2007 11:55 AM ET (US)
Once you understand what each component does you will find that the 3 cylinder Optimax engines are relatively simple.
They are easy to work on and the spark plugs are VERY easy to remove relative to other Optimax engines. Routine service is a snap (changing fuel filter, spark plugs, gear oil, lubing zirc fittings, etc)
This engine has a VERY similar block design to the standard 90hp 2 stroke. The internal parts come from the 3.0 litre Optimax...so the parts are VERY beefy. There is NO CYLINDER HEAD to deal with...so no o-rings or head gasket to cause problems. Think of this motor as a 2 stroke that has a few new components added to the outside of the block...such as a high output belt driven alternator, an air compressor, and the addition of Direct Fuel Injection which uses 6 injectors instead of 3. The plumbing and wiring is very straightforward. There are NO VALVES like a 4 stroke to worry about. No oil filter or crankcase oil to change. They run smooth and quiet just like a 4 stroke and they sip gas like a 4 stroke. There is quite alot of space under the cowl on the 3 cylinder...it makes the engine appear larger than necessary to some, but I like having some room to get my hands on things, so I don't mind. Merc has made VERY FEW changes to the 3 cylinder Optimax engines.....because they got it right the first time !!
jimh posted 02-17-2007 04:11 PM ET (US)
I understand what everything under the cowling does, except perhaps for several of those Schraeder valves. But the engine just does not have that look of a modern engine. Modern engines possess a certain quality of neatness and order. If there are hoses and wiring harnesses, they tend to be very carefully placed and dressed onto the engine block. Every hose seems to be a pre-bent molded hose specialized for the individual connection. A modern engine is really quite attractive and if there is some haywire, it is hidden with a shroud or molded cover.
The OptiMax, just as you described, looks like an old fashioned two-stroke with all sorts of extra stuff bolted on to it. Then it all gets connected by hoses and wiring. I am sure that after you study the engine and work on it for a while, it becomes more straightforward, but I am thinking about a guy who takes that cowling off for the first time. He is going to be staring at quite a collection of stuff.
The performance is reported to be quite good on these motors, and I know that the three-cylinder motors give a very good account of themselves. But they are quite large, both in displacement and overall size and weight. I think that holds them back.
sosmerc posted 02-17-2007 06:30 PM ET (US)
Until I get a close look under the cowl of a new Merc 115 EFI FourStroke, I'm going to have to withhold my opinions about how well the packaging looks. Many of today's "modern" engines use a great deal of plastic "beauty covers" to clean up the looks under the bonnet. Once removed, I think you will find an abundance of wires, hoses, sensors, etc...no matter what brand of engine you are looking at. Some do a better job of providing a "neat" appearance...and obviously you think Merc hasn't done a very good job on the Optimax. I'm not going to argue because I know there is always room for improvement. I do feel that if you set a new Merc EFI 4 stroke up next to a new 115 Optimax the FourStroke is still going to look much bigger and bulkier...and indeed, it is alot heavier and has alot more moving parts on it...as well as more covers, bolts, gaskets, etc. Here's something you could research to prove my point...count the number of parts on each motor and compare. (I haven't done it, but I'm willing to bet the FourStroke has close to double the actual parts ! )
Mambo Minnow posted 02-17-2007 09:04 PM ET (US)
Did you see any new components under the cowl that would reduce noise signature? Allegedly, the G2 would have different sound baffling or insulation to reduce the well known decibel level.
Removing the lower spark plugs on the six cylinder is very difficult. Many DIYers have crossed the threads. I do agree this is a motor that is best left to the professionals to maintain. That said, I am not sure how much better the E-tec is in this regard, despite the 3 years/no maintenance spin.
sosmerc posted 02-18-2007 12:17 AM ET (US)
The 3 cylinder G2 motors have no significant changes. They already have a "muffler" on the excess air path. This muffler has now been added to the 3.0 litre Optimax as well as some new cowling baffles...so the sound signiture on the 3.0 litre Optimax engines are quieter. Some of the SmartCraft data streams have been changed to permit easy understanding of Guardian System warning messages.
bsmotril posted 02-18-2007 11:01 AM ET (US)
Is not having a separate cylinder head a real benfit? I would think that it would raise the amount of labor hours needed to repair something like a broken ring or scored cylinder. And the cost of the replacement block casting would likely be higher also because of the part's complexity compared to an old block. And lastly, is it possible to bore such a block oversize and re-use it with a step up piston if you just want to repair one hole?
BillS
sosmerc posted 02-18-2007 11:32 AM ET (US)
Replacing a piston or rings or major overhaul is not complicated by Merc's cast in head design. In fact, the pistons are installed without need for ring compressors because the cylinder is tapered to facilitate installation.
I don't believe the design is more costly...many oem's are using lost foam casting for their blocks.
You can bore the cylinders oversize and use oversize pistons and rings, just like any other engine. Not every machine shop can do the job though...they have to be setup to work in a blind hole. But since Merc has used this design for ages, most marine machine shops can do it.
These are easy engines to work on and thus should be less expensive to repair...especially in comparison to 4 strokes.
jimh posted 02-18-2007 11:53 AM ET (US)
In this OptiMax G2 or OptiMax Globe engine I observed that there was a separate belt-driven automotive-style alternator with integral rectifier and voltage regulator as opposed to an under-flywheel permanent magnet alternator with external rectifier and regulator. However, I make the assumption that there still must be an under-flywheel coil assembly ("stator") and permanent magnets mounted in the flywheel as part of the engine ignition system. I forgot to look closely for these electrical components under the flywheel.
Perhaps an experienced OptiMax technician such as sosmerc could comment on this. Is there still a stator coil assembly under the flywheel on the OptiMax G2 motor?
sosmerc posted 02-18-2007 12:29 PM ET (US)
No, the alternator provides all of the electrical power needed to run the engine. There are NO magnets in the flywheel...just special "teeth" for the crank position sensor to "count". Merc uses the same belt driven alternator on the 75hp Optimax all the way up to the 300hp Optimax. It may even be the same alternator that is used on the Verado...I haven't checked that out yet.
sosmerc posted 02-18-2007 01:21 PM ET (US)
Just for kicks, I did a little research on alternators. The Verado alternator puts out 70 Amps. The Optimax Alternator puts out 60 Amps, and the 75-115 EFI 4 stroke puts out 50 Amps.
So while they all have belt driven alternators that look similar, their specs are different and I would guess they come from different suppliers as the Optimax alternator shows up on Merc's Parts Express site as being $200 more expensive than the Verado alternator. Go figure.
jimh posted 02-18-2007 05:39 PM ET (US)
OK--It sounds like the OptiMax G2 ignition system is not self-powered. This would fit with the anecdotal reports about the OptiMax needing a very strong battery for starting and running. The classic two-stroke like my old Evinrude has a self-powered ignition system, and it can start and run without a battery.
Once that OptiMax G2 fires up, the alternator--which also is not self exciting and needs a battery to provide the initial current to generate a magnetic field--can take over and generate plenty of electrical power.
Bottom line: better have a strong battery to get that OptiMax G2 cranking and firing.
gss036 posted 02-18-2007 07:23 PM ET (US)
Jimh, I made that same comment to a poster about buying an Opti-Max in Alaska. Also included to him, that it would be to his benefit to learn how to change the drive belt on the water, if that is possible? I don't know? Makes me leary of the set up, just my 2 cents!
sosmerc posted 02-18-2007 08:29 PM ET (US)
I have NEVER seen an Optimax drive belt break...but if it did, It is VERY easy to replace. The only tool that is needed is a 3/8ths square drive rachet or breaker bar (no socket required...just the wrench). The Optimax motors do require a good strong starting battery (min 1000 MCA). But most modern large outboards require a strong starting battery...is this a big deal?
sosmerc posted 02-18-2007 08:38 PM ET (US)
P.S. I forgot to mention that I have seen NUMEROUS failures of stators, rectifiers, switchboxes on Mercs and Johnson/Evinrude products. Try changing any of these components on the water in a pinch....I'd much rather be faced with replacing an alternator belt on an Optimax while on the water (though I have never had to :)
The Optimax basically has a battery ignition just like the Verado...and the ignition system used on 99.9% of the cars on the road today. It doesn't get any more reliable than that.
jimh posted 02-19-2007 10:08 AM ET (US)
I agree with sosmerc--the drive belt looked very straightforward and easy to replace.
The automotive style alternator is a reliable and proven design. However, there is some irony here.
Automobiles are finding that their electrical systems are growing and need more electrical power. The belt-driven alternator cannot keep up, and some cars are moving to a permanent magnet alternator built into the engine flywheel--just like an old two-stroke. Also, there are now permanent magnet alternators which are belt driven. The permanent magnet alternator is more efficient, generally. In automobiles there is a constant search for ways to improve fuel efficiency, so making the alternator more efficient has become one way to make the vehicle get better gas mileage. You may see that automobiles will be going back to the old outboard motor style of alternator more and more.
jimh posted 02-19-2007 10:22 AM ET (US)
I also agree with sosmerc on the relatively frequent occurrence of failure with the stator coils associated with under-flywheel permanent magnet alternators--too often! These coils are usually done in by heat. The heat is either from the engine itself or from excessive current flow in the windings due to the failure of the external rectifier or regulator components. Some new two-stroke motors have fan blades molded into the flywheel to create air flow over this area of the motor. (See http://continuouswave.com/ubb/Forum6/HTML/001168.html .)
However, many old-fashioned two-stroke motors will keep running even if their battery charging system has failed. I used to have a Mercury 500 (50-HP) motor that was in very good tune. It started on the first crank. I did not have any electrical accessories on the boat. And I always kept the battery topped off with a 120-VAC charger when the boat was not being used. I took the boat on a week's vacation and discovered on day six that the battery was dead. It turned out the rectifier was bad and there had been no battery charging current from that motor--for who knows how long! Five days of starting the motor four or five times a day had finally run the battery down. I never noticed because once the motor started everything in its ignition system was self-powered, so it did not care about the battery charging circuit being kaput. The rectifier was a separate part, so it only cost $30 to replace it.

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Author	Topic: OptiMax G2--The Globe Motors
jimh	posted 02-17-2007 10:48 AM ET (US) Just this week at the nearly empty Detroit Boat Show--where I was literally often the only person in an exhibit space--I stopped to chat with the four salesmen at the Bass Pro Shop exhibit. They were nice enough to help me get the cowling off a new Mercury OptiMax G2 90-HP motor. Here are my impressions: First of all, the new graphics with the globe logo are very good. They immediately allow you to identify the OptiMax motor from other Mercury products. In the recent past it seemed like Mercury was embarrassed about their motor model names and hid them in very small logotypes visible only from the interior of the boat. All their motors had similar black cowlings with just MERCURY on the side, leaving you no way to tell what sort of motor it was. Now you can spot an OptiMax G2 from the cowling decals. Also, the designator OptiMax The Next Generation (OTNG) seems to have fallen aside, so we'll just call these OptiMax G2 motors or OptiMax Globe motors. To look inside the first thing you need, of course, is to remove the cowling. Again, I am glad to say, Mercury has drastically improved their product. The cowling latch on the OptiMax G2 is at the rear. It released to the open position with a nice feel and sound. (This immediately gave me a much better feeling about the motor. The last time I tried to look under an OptiMax cowling I practically had to pry the latches loose and the cowling was very reluctant to move.) Next, the salesman and I hunted around for a minute or two for the front cowling release. But there was none. Eventually we figured out the cowling comes off by raising the rear, cocking it a bit, and sliding it forward. This disengages the forward latch mechanism, and then you lift the cowling off the motor. The cowling is a plastic molding that has moderate weight. The black color is molded into the material, so it should be quite durable. We set the cowling aside and I gave the motor a close look. The top of the motor and the starboard side have two plastic panels covering them. These are retained with press-on rubber grommets that fit over mounting posts. They came off without much fuss, and the engine's configuration was revealed. The salesman was starting to look at me with a bit of suspicion, perhaps thinking at this point maybe he had made a mistake letting me take the cowling off. The top cover is a shroud that covers the belt and pulleys that connect the flywheel, the alternator, the air compressor, and the belt tensioner. There is some step-up in the pulley ratio, so when the engine is spinning the flywheel at 6,000-RPM the alternator will be whizzing around even faster. The belt tensioner pulley must spin over 10,000-RPM to keep pace. The business end of the starter motor is under the shroud. It looks like a nice compact starter unit. The starboard side cover conceals electrical connectors and components. I like to look at an engine and see if I can figure out what all the wires and hoses are doing. On the OptiMax this is a challenge. There are a lot of wires and hoses. The first things I looked for were the spark plugs. The upper two cylinders have plugs which are easy to see and reach. The bottom cylinder has a plug that is well below the level of the mid-section shroud. Getting a wrench on that plug will be a challenge. You may need to remove the midsection shroud to reach it. There is not much room to back the plug out, as a hose or wiring harness lies right atop the plug. The plugs have separate ignition coils. The three coils are located nearby, connected to the plugs with about 8-inches of high-tension wire. This is the old-fashioned approach to ignition and spark plugs. I would not call it "next generation." Modern engines have a coil-on-plug design, like Mercury used in the Verado. For some reason two-stroke engines all seem to have separate coils. Next I found the six injectors. Yes, six injectors even though this is only a three-cylinder engine. There are separate air injectors and fuel injectors. They form quite a complex assembly atop each cylinder which has both a pressurized fuel rail and a pressurized air rail. There are several valve stems with Schraeder valves; I guessed these must be used for bleeding the system or for attaching diagnostic gauges. The fuel and air rails have hoses coming and going. The six injectors all have an electrical wiring harnesses attached to them with connectors. And there are the spark plugs. So each cylinder has quite a collection of wires and hoses associated with it. Since this is a two stroke engine, there is also an oil pump, a distribution manifold, and a spaghetti of hoses carrying oil to injections points in the engine block. This pump looks like it is operated electrically. The fuel system has a very big vapor separator and filter assembly. It appears to be a metal casting. The shape is quite odd. It looks like it was custom molded to fit someplace else. In the OptiMax G2 this assembly is just bolted on the port side of the engine, and all manner of hoses come and go from it at strange places and odd angles. It does not look like it was designed to fit into this particular engine or the space available for it. The electrical system is mainly on the starboard side. It looks like the relays for the tilt and trim system are bolted to the engine block quite far below the level of the midsection shroud. It was hard to see them, and impossible to reach them. You would have to remove the midsection shroud to get to them. That is not a big problem, but what worried me more was the low position in the midsection. I think it is inevitable that water gets inside the cowling once in a while. With all of those electrical components mounted so low, I have a concern with them getting soaked in water. The relays look like they are sealed and potted in a plastic assembly, but it never seems like a good idea to put electrical components low in the engine cowling. The OptiMax looks like a motor that will need a professional mechanic to perform work on it. Even a usual owner activity like changing a spark plug is going to be a challenge. The presence of so many valves and ports in the fuel systems seems like an indication that some specialized equipment may be needed to work on it, too. When I compare the OptiMax G2 to my old classic two-stroke, I see many new components under the cowling that I don't have on the old engine: --separate alternator with belt drive and belt tensioner --separate air compressor --large fuel-vapor separator filter --complex pressurized fuel and air rails --separate oil pump and oil distribution system It is no wonder that these OptiMax engines are large--they have many more components under their cowlings than a classic two-stroke. I guess that is why this 90-HP motor is so much bigger than an old 90-HP Yamaha two-stroke. This 90-HP is about the same size as the classic Mercury 2.5-liter 200-HP engine. My general impression of the new 90-HP OptiMax G2 is that the cowling is much improved, both in appearance and in its mechanics. However, under the cowling I did not see much evidence of a change that would reflect a "new generation" of engine. The engine layout still seems to be a confusing mass of hoses and wires which connect components that do not look like they were designed to fit into specific spaces. In comparison, the new Mercury FourStroke (or Veradito) motors appear better designed to fit all components together in a efficient manner.
sosmerc	posted 02-17-2007 11:55 AM ET (US) Once you understand what each component does you will find that the 3 cylinder Optimax engines are relatively simple. They are easy to work on and the spark plugs are VERY easy to remove relative to other Optimax engines. Routine service is a snap (changing fuel filter, spark plugs, gear oil, lubing zirc fittings, etc) This engine has a VERY similar block design to the standard 90hp 2 stroke. The internal parts come from the 3.0 litre Optimax...so the parts are VERY beefy. There is NO CYLINDER HEAD to deal with...so no o-rings or head gasket to cause problems. Think of this motor as a 2 stroke that has a few new components added to the outside of the block...such as a high output belt driven alternator, an air compressor, and the addition of Direct Fuel Injection which uses 6 injectors instead of 3. The plumbing and wiring is very straightforward. There are NO VALVES like a 4 stroke to worry about. No oil filter or crankcase oil to change. They run smooth and quiet just like a 4 stroke and they sip gas like a 4 stroke. There is quite alot of space under the cowl on the 3 cylinder...it makes the engine appear larger than necessary to some, but I like having some room to get my hands on things, so I don't mind. Merc has made VERY FEW changes to the 3 cylinder Optimax engines.....because they got it right the first time !!
jimh	posted 02-17-2007 04:11 PM ET (US) I understand what everything under the cowling does, except perhaps for several of those Schraeder valves. But the engine just does not have that look of a modern engine. Modern engines possess a certain quality of neatness and order. If there are hoses and wiring harnesses, they tend to be very carefully placed and dressed onto the engine block. Every hose seems to be a pre-bent molded hose specialized for the individual connection. A modern engine is really quite attractive and if there is some haywire, it is hidden with a shroud or molded cover. The OptiMax, just as you described, looks like an old fashioned two-stroke with all sorts of extra stuff bolted on to it. Then it all gets connected by hoses and wiring. I am sure that after you study the engine and work on it for a while, it becomes more straightforward, but I am thinking about a guy who takes that cowling off for the first time. He is going to be staring at quite a collection of stuff. The performance is reported to be quite good on these motors, and I know that the three-cylinder motors give a very good account of themselves. But they are quite large, both in displacement and overall size and weight. I think that holds them back.
sosmerc	posted 02-17-2007 06:30 PM ET (US) Until I get a close look under the cowl of a new Merc 115 EFI FourStroke, I'm going to have to withhold my opinions about how well the packaging looks. Many of today's "modern" engines use a great deal of plastic "beauty covers" to clean up the looks under the bonnet. Once removed, I think you will find an abundance of wires, hoses, sensors, etc...no matter what brand of engine you are looking at. Some do a better job of providing a "neat" appearance...and obviously you think Merc hasn't done a very good job on the Optimax. I'm not going to argue because I know there is always room for improvement. I do feel that if you set a new Merc EFI 4 stroke up next to a new 115 Optimax the FourStroke is still going to look much bigger and bulkier...and indeed, it is alot heavier and has alot more moving parts on it...as well as more covers, bolts, gaskets, etc. Here's something you could research to prove my point...count the number of parts on each motor and compare. (I haven't done it, but I'm willing to bet the FourStroke has close to double the actual parts ! )
Mambo Minnow	posted 02-17-2007 09:04 PM ET (US) Did you see any new components under the cowl that would reduce noise signature? Allegedly, the G2 would have different sound baffling or insulation to reduce the well known decibel level. Removing the lower spark plugs on the six cylinder is very difficult. Many DIYers have crossed the threads. I do agree this is a motor that is best left to the professionals to maintain. That said, I am not sure how much better the E-tec is in this regard, despite the 3 years/no maintenance spin.
sosmerc	posted 02-18-2007 12:17 AM ET (US) The 3 cylinder G2 motors have no significant changes. They already have a "muffler" on the excess air path. This muffler has now been added to the 3.0 litre Optimax as well as some new cowling baffles...so the sound signiture on the 3.0 litre Optimax engines are quieter. Some of the SmartCraft data streams have been changed to permit easy understanding of Guardian System warning messages.
bsmotril	posted 02-18-2007 11:01 AM ET (US) Is not having a separate cylinder head a real benfit? I would think that it would raise the amount of labor hours needed to repair something like a broken ring or scored cylinder. And the cost of the replacement block casting would likely be higher also because of the part's complexity compared to an old block. And lastly, is it possible to bore such a block oversize and re-use it with a step up piston if you just want to repair one hole? BillS
sosmerc	posted 02-18-2007 11:32 AM ET (US) Replacing a piston or rings or major overhaul is not complicated by Merc's cast in head design. In fact, the pistons are installed without need for ring compressors because the cylinder is tapered to facilitate installation. I don't believe the design is more costly...many oem's are using lost foam casting for their blocks. You can bore the cylinders oversize and use oversize pistons and rings, just like any other engine. Not every machine shop can do the job though...they have to be setup to work in a blind hole. But since Merc has used this design for ages, most marine machine shops can do it. These are easy engines to work on and thus should be less expensive to repair...especially in comparison to 4 strokes.
jimh	posted 02-18-2007 11:53 AM ET (US) In this OptiMax G2 or OptiMax Globe engine I observed that there was a separate belt-driven automotive-style alternator with integral rectifier and voltage regulator as opposed to an under-flywheel permanent magnet alternator with external rectifier and regulator. However, I make the assumption that there still must be an under-flywheel coil assembly ("stator") and permanent magnets mounted in the flywheel as part of the engine ignition system. I forgot to look closely for these electrical components under the flywheel. Perhaps an experienced OptiMax technician such as sosmerc could comment on this. Is there still a stator coil assembly under the flywheel on the OptiMax G2 motor?
sosmerc	posted 02-18-2007 12:29 PM ET (US) No, the alternator provides all of the electrical power needed to run the engine. There are NO magnets in the flywheel...just special "teeth" for the crank position sensor to "count". Merc uses the same belt driven alternator on the 75hp Optimax all the way up to the 300hp Optimax. It may even be the same alternator that is used on the Verado...I haven't checked that out yet.
sosmerc	posted 02-18-2007 01:21 PM ET (US) Just for kicks, I did a little research on alternators. The Verado alternator puts out 70 Amps. The Optimax Alternator puts out 60 Amps, and the 75-115 EFI 4 stroke puts out 50 Amps. So while they all have belt driven alternators that look similar, their specs are different and I would guess they come from different suppliers as the Optimax alternator shows up on Merc's Parts Express site as being $200 more expensive than the Verado alternator. Go figure.
jimh	posted 02-18-2007 05:39 PM ET (US) OK--It sounds like the OptiMax G2 ignition system is not self-powered. This would fit with the anecdotal reports about the OptiMax needing a very strong battery for starting and running. The classic two-stroke like my old Evinrude has a self-powered ignition system, and it can start and run without a battery. Once that OptiMax G2 fires up, the alternator--which also is not self exciting and needs a battery to provide the initial current to generate a magnetic field--can take over and generate plenty of electrical power. Bottom line: better have a strong battery to get that OptiMax G2 cranking and firing.
gss036	posted 02-18-2007 07:23 PM ET (US) Jimh, I made that same comment to a poster about buying an Opti-Max in Alaska. Also included to him, that it would be to his benefit to learn how to change the drive belt on the water, if that is possible? I don't know? Makes me leary of the set up, just my 2 cents!
sosmerc	posted 02-18-2007 08:29 PM ET (US) I have NEVER seen an Optimax drive belt break...but if it did, It is VERY easy to replace. The only tool that is needed is a 3/8ths square drive rachet or breaker bar (no socket required...just the wrench). The Optimax motors do require a good strong starting battery (min 1000 MCA). But most modern large outboards require a strong starting battery...is this a big deal?
sosmerc	posted 02-18-2007 08:38 PM ET (US) P.S. I forgot to mention that I have seen NUMEROUS failures of stators, rectifiers, switchboxes on Mercs and Johnson/Evinrude products. Try changing any of these components on the water in a pinch....I'd much rather be faced with replacing an alternator belt on an Optimax while on the water (though I have never had to :) The Optimax basically has a battery ignition just like the Verado...and the ignition system used on 99.9% of the cars on the road today. It doesn't get any more reliable than that.
jimh	posted 02-19-2007 10:08 AM ET (US) I agree with sosmerc--the drive belt looked very straightforward and easy to replace. The automotive style alternator is a reliable and proven design. However, there is some irony here. Automobiles are finding that their electrical systems are growing and need more electrical power. The belt-driven alternator cannot keep up, and some cars are moving to a permanent magnet alternator built into the engine flywheel--just like an old two-stroke. Also, there are now permanent magnet alternators which are belt driven. The permanent magnet alternator is more efficient, generally. In automobiles there is a constant search for ways to improve fuel efficiency, so making the alternator more efficient has become one way to make the vehicle get better gas mileage. You may see that automobiles will be going back to the old outboard motor style of alternator more and more.
jimh	posted 02-19-2007 10:22 AM ET (US) I also agree with sosmerc on the relatively frequent occurrence of failure with the stator coils associated with under-flywheel permanent magnet alternators--too often! These coils are usually done in by heat. The heat is either from the engine itself or from excessive current flow in the windings due to the failure of the external rectifier or regulator components. Some new two-stroke motors have fan blades molded into the flywheel to create air flow over this area of the motor. (See http://continuouswave.com/ubb/Forum6/HTML/001168.html .) However, many old-fashioned two-stroke motors will keep running even if their battery charging system has failed. I used to have a Mercury 500 (50-HP) motor that was in very good tune. It started on the first crank. I did not have any electrical accessories on the boat. And I always kept the battery topped off with a 120-VAC charger when the boat was not being used. I took the boat on a week's vacation and discovered on day six that the battery was dead. It turned out the rectifier was bad and there had been no battery charging current from that motor--for who knows how long! Five days of starting the motor four or five times a day had finally run the battery down. I never noticed because once the motor started everything in its ignition system was self-powered, so it did not care about the battery charging circuit being kaput. The rectifier was a separate part, so it only cost $30 to replace it.