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Author Topic:   Trouble Shifting Mercury Four-cycle Motor

radgroup posted 02-04-2008 11:01 AM ET (US)
I have a 2005 90-HP Mercury four-cycle on my Montauk. It has always been a little stiff shifting. Recently it seems fine when I start out, but after running about 20 minutes the shifting gets very stiff. My local Mercury service thinks it might be a electronic switch that shuts off two cylinders when shifting and it may be not working. He suggests replacing the switch. Does that sound like a reasonable cause for this problem?
dbrown posted 02-04-2008 06:34 PM ET (US)
Never heard of a Mercury 90 that shuts down cylinders. Sounds like when the fluid warms up and thins, it get tougher to shift. My 90 FourStroke is also hard to shift at times. Especially when coming out of gear to neutral. Sounds like yours is getting worse with time though...
swist posted 02-05-2008 09:01 AM ET (US)
The shifters on that generation of motors were the subject of a lot of discussion here, probably a year ago. I'm sure a little searching will find the topics. In summary, the detents are vague, the action can be stiff, and it can be hard to get a smooth shift without grinding gears. Most of us have learned to cope.
Unfortunately, if you have a real problem with your shifting mechanism, it can get masked by the poor design of the shifter.

Marlin posted 02-05-2008 09:14 AM ET (US)
I don't believe that there is a cylinder shutdown on the Mercury 4-strokes (that is, the not-quite current 90 and 115 engines with the Yamaha powerheads); it's certainly not apparent given the whump that they typically shift with, and I don't recall seeing anything about it in my service manual.
My 2003 115 shifts with a grind and a clunk, has a poorly-defined neutral position without a detent on the shifter, and requires practice to avoid accidentally going into the opposite gear when trying to shift into neutral.
Again, as swist said, with practice you deal with it and it becomes not a very big deal. If yours is particularly difficult, I'd recommend a change of the lower unit lube.
-Bob
radgroup posted 02-05-2008 10:50 AM ET (US)
Thanks everyone for your suggestions.
montaukman posted 02-05-2008 04:38 PM ET (US)
I had this same problem on my 4 stroke 90 (when I had my 170). You need to shift quickly and decively otherwise you will get the grinding noise. Also it was difficult to know where and what gear you were in since there was not a really good detent feel. Mine was also stiff.
I seem to recall that the loud thunk you get when going into and out of gear was due to the weight of the stainless prop that came with the 4 strokes. Used to annoy the heck out of me. My buddy had an older merc that ran great and never did that and he used to tease me about the money I spent and how his shifted so much more effortlessly.
Good Luck,
Alan
Marlin posted 02-05-2008 08:24 PM ET (US)
Yes, at least part of the thunk is supposedly due to the heavy stainless props. The Flo-Torq III hub is supposed to help alleviate that. I'm hoping to try one out this spring.
-Bob
bigjohn1 posted 02-05-2008 11:42 PM ET (US)
Without a doubt, switching to the Flo-Torq III hub will greatly improve the way this engine shifts and acts at low speed. Tom Clark recommended this to me and it really improved things.
There is no “electronic switch” on your engine that switches cylinders off during shifting. The ECU computer will begin to shut down certain cylinders when you over-rev the engine but that’s an entirely different situation. If you don’t want to believe me, buy the official factory manual for your engine (not the puny little owner’s manual you got with the boat). It has a very detailed explanation of the ignition and fuel delivery systems and will explain things to very clearly.
montaukman posted 02-06-2008 09:04 AM ET (US)
Hi,
I thought on the Merc 90 4 stroke, when you are running below a certain RPM, only some cylinders are working and once past that RPM you get the full power. I don't remember where I heard it but it sounds familiar to me.
Alan
sosmerc posted 02-09-2008 11:53 AM ET (US)
Your 2005 90hp Merc 4 stroke runs on all 4 cylinders all the time. I have encountered the "shift problem" you describe on a number of my customer engines.
Merc has addressed the issue on the very latest engines in that horsepower class by redesigning the shift mechanism inside the gearcase. According to my brief research, the changes cannot easily be made to older gearcases.
The only thing that you can do to improve the quality of shifting on your motor is: make sure the engine is idling as slow as possible before attempting to shift from forward back to neutral. Install the latest model remote control with the Gen II low friction cables. Replace your lower unit with the newest version that has the new desmodronic shift system.
Perhaps Merc will come up with some kind of "retro-fit" kit for older 4 stroke engines that experience the problem. The newer engines produce much more torque than the old 90 2 strokes at idle and this creates issues when trying to dis-engage the clutch. (the gearcase used on the early 4 stroke 75/90/115 is very nearly the same as the gearcase used on the 75/90 L3 2 stroke)
dbrown posted 02-09-2008 09:06 PM ET (US)
sosmerc, do you think switching to a different lubricant would help or is this strictly a mechanical problem? Oddly enough, my engine (90 FOURSTROKE) has the desmodronic shift system and it's still a bit fickle. I'm currently using the Merc. Premium. I was thinking of switching to the High Performance Gear Lube...
sosmerc posted 02-10-2008 12:26 PM ET (US)
dbrown...can you post your serial number? I'd like verify that you really do have the latest shift design.
I do recommend the Merc High Performance gear lube, but I don't think it is going to make any difference with regards to this issue.
I would disconnect the throttle and shift cables and see how much effort it takes to shift the engine manually back at the motor. It would be best to do this with the boat in the water. The engine needs to be warmed up and idling as slow as possible.
I would also (with the cables still disconnected) shift the remote control through its full range...it should be very smooth and effortless.
I have not yet had a chance to "play" with one of the very latest gearcases, but I am hoping to see a MAJOR improvement. (I'm hoping your engine isn't the latest design...I'd hate to find out that the "fix" hasn't been that successful).
Please keep us posted.
Thanks.
dbrown posted 02-10-2008 03:14 PM ET (US)
Thanks for the reply sosmerc. My serial number is 1B466307. What I have noticed is that the hard shifting is most prevalent when the boat is still moving at a small forward or backward motion, such as when docking or moving at idle speed in gear. It's then that you need to be more aggressive when pulling the control back to neutral. Not so much when the boat is totally stopped. Anything you can find out would be appreciated..
sosmerc posted 02-10-2008 06:34 PM ET (US)
Using your serial number I did verify that you have the newest gearcase design. Next I would ask specifically what control is used in your boat as well as the specific control cables. And what is your idle rpm after the engine is completely warmed up. Maybe in your case it is a rigging problem.
How does it shift from forward to neutral with the engine OFF? (never attempt to shift from neutral to reverse without the engine running or someone turning the prop....neutral to forward and forward back to neutral with the engine off is ok)
How long have you had this rig and has it ever been back to the shop for any adjustments? Was it a repower, or a new boat with matching new controls and rigging?
I'm very interested in resolving this problem.
jimh posted 02-10-2008 08:10 PM ET (US)
In an earlier article I wrote about the change Mercury made to the shifting mechanism of their outboard motors in which they improved the mechanism by employing a desmodromic actuator. See:
http://continuouswave.com/ubb/Forum1/HTML/015209.html
In that article the 90-HP motors are mentioned, and the epoch of c.2005 is mentioned as when the desmodromic mechanism was introduced in that model.
It is somewhat common that in high power motors an ignition interruption circuit is actuated during the shift process in order to momentarily reduce the torque produced by the motor and allow the gears to disengage more easily. This is seen on V6 motors in the 200-HP range.
I have confidence in sosmerc's knowledge, and I would put more weight on his opinion (that such an ignition cut out is not employed on a 90-HP Mercury four-cycle motor with a Yamaha power head) than on the contrary opinion of your local mechanic.
A lot of Mercury outboard engineering was revised during the period (2000 to 2005) when George Buckley was the CEO and he hired German auto engineer Claus Bruestle from Porsche to take charge of their four-cycle outboard motor development program. Claus told this anecdote about his experience with Mercury outboard motor shift mechanisms during an interview he gave when the Verado motor was being introduced:

quote:
When I joined Mercury, people were very nice to me and taught me how to drive and dock a boat. I remember one of my first experiences driving a boat, when I shifted and it made this great clunk. I said, "We are going to stop this—it sounds like a 1950s truck." People said, "Why? It's always been that way." I said, "Exactly."
(The Verado motor, by the way, had a completely new design for the gear case and used electrical motors and actuators to accomplish the shifting. It shifts beautifully and without any KLUNK.)
I think what you are experiencing in this particular motor is some of that Mercury engineering that was pre-Claus Bruestle. At the time your engine was being made, c.2005, Mercury knew it would be abandoning that design in the near future. In c.2007 Mercury replaced the Yamaha-Mercury 90-HP with the new Veradito model, based on the Verado block, which probably has a different gear case.
Ultimately, both Buckley and Bruestle left Mercury.
In all older outboard motors, part of the shifting process is learning how to shift in a manner that is most compatible with the particular gear case you are using. Most of them like quick, firm shifts which rapidly engage or disengage the gears. Being tentative with the shift mechanism does not lead to smooth shifts.
In addition, if your cable mechanisms have any stretch or elasticity, or if your shifter lever and actuators are not properly aligned, you may have difficulty. Check the cables and the shift alignment to make sure all is well.

dbrown posted 02-10-2008 08:37 PM ET (US)
It shifts fine when the engine is off or when the boat is stationary and the engine is running. The engine idles right at 700 RPM's, which per the manual is correct. I bought the boat and motor new last April. It has been back for a starter replacement and at that time I had them check the linkage. They said is was correct and the shifting characteristics were normal. It has the standard cables and the Binnacle control MCC 4501..
OutrageMan posted 02-10-2008 08:45 PM ET (US)
Just a point of order.
1) Buckley was CEO of Brunswick, Pat Mackey is (was then) President of Mercury Marine.
2) Claus was hired by Fred Brightbill, then President of Mercury Outboard Division (he and Claus were the chiefs responsible for Verado).
Of all of those people, Mackey is the only one left.
Brian
sosmerc posted 02-11-2008 11:20 AM ET (US)
Just for clarification...dbrown's motor is the latest Verado-based 4 cylinder 90hp 4 stroke and it uses the latest design shift system (desmodronic). I have not had my hands on one of these yet, but I would bet that there is a switch associated with the shift arm that basically tells the engine computer when the engine is in neutral and when it has shifted. I do not call it a "shift switch" simply because it does not have any effect on shift effort.
The engine has "overspeed" protection in neutral...and the engine computer needs to know when the motor is in neutral.
radgroup (that started this thread) has the older design 90hp 4 stroke and his gearcase is the older design. I really don't recall if it has a shift activated switch or not, but if it does it most likely functions the same as the Verado-based system.
sosmerc posted 02-11-2008 11:30 AM ET (US)
dbrown...your MC 4500 control should be a Gen II control and thus uses the low friction Gen II cables. You might check to see that the cables have at least a couple of feet of unrestricted routing behind the box. (the cables MUST be free to move) Make sure they are not tie-wrapped together or to anything else for the first couple of feet after they come out of the control.
I guess it is a judgement call on your part as to whether or not you have a problem. If the shifting effort takes away from your pleasure or causes any safety issues (such as your ability to dock or get the boat easily on the trailer) I would get the dealer to take a closer look.
sosmerc posted 02-11-2008 01:07 PM ET (US)
radgroup...what is your serial number? (I don't think your engine has any switch associated with your shift system, but I would like to confirm that)
dbrown posted 02-11-2008 02:02 PM ET (US)
Thank you sosmerc for looking into it. This is only my second Merc.(I had an older 67' model 650 that, by the way, shifted like a dream) and I guess I was expecting ths one to be better than it is. Before I bought this engine, I had the opportunity on many occasions to drive a boat with an older (late 90's model) Merc. XR6 and it had the same characteristics, but also had what I thought was an enormous clunk when shifting into gear. I spoke at length with the dealer about this concern before I bought and was assured that the new models had addressed that problem. On the bright side, mine just has a very small thud when engaging forward or reverse. Also, having had many Johnson/Evinrudes for the past 20 years, maybe I'm just spoiled by their buttery smooth shifting. I will look into the cable routing and let you know if I find any problem there...
sosmerc posted 02-11-2008 03:12 PM ET (US)
As mentioned before, the Merc FloTorq III hub will reduce the "clunk" and clutch rattle, but not the ease or effort of shifting.

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Author	Topic: Trouble Shifting Mercury Four-cycle Motor
radgroup	posted 02-04-2008 11:01 AM ET (US) I have a 2005 90-HP Mercury four-cycle on my Montauk. It has always been a little stiff shifting. Recently it seems fine when I start out, but after running about 20 minutes the shifting gets very stiff. My local Mercury service thinks it might be a electronic switch that shuts off two cylinders when shifting and it may be not working. He suggests replacing the switch. Does that sound like a reasonable cause for this problem?
dbrown	posted 02-04-2008 06:34 PM ET (US) Never heard of a Mercury 90 that shuts down cylinders. Sounds like when the fluid warms up and thins, it get tougher to shift. My 90 FourStroke is also hard to shift at times. Especially when coming out of gear to neutral. Sounds like yours is getting worse with time though...
swist	posted 02-05-2008 09:01 AM ET (US) The shifters on that generation of motors were the subject of a lot of discussion here, probably a year ago. I'm sure a little searching will find the topics. In summary, the detents are vague, the action can be stiff, and it can be hard to get a smooth shift without grinding gears. Most of us have learned to cope. Unfortunately, if you have a real problem with your shifting mechanism, it can get masked by the poor design of the shifter.
Marlin	posted 02-05-2008 09:14 AM ET (US) I don't believe that there is a cylinder shutdown on the Mercury 4-strokes (that is, the not-quite current 90 and 115 engines with the Yamaha powerheads); it's certainly not apparent given the whump that they typically shift with, and I don't recall seeing anything about it in my service manual. My 2003 115 shifts with a grind and a clunk, has a poorly-defined neutral position without a detent on the shifter, and requires practice to avoid accidentally going into the opposite gear when trying to shift into neutral. Again, as swist said, with practice you deal with it and it becomes not a very big deal. If yours is particularly difficult, I'd recommend a change of the lower unit lube. -Bob
radgroup	posted 02-05-2008 10:50 AM ET (US) Thanks everyone for your suggestions.
montaukman	posted 02-05-2008 04:38 PM ET (US) I had this same problem on my 4 stroke 90 (when I had my 170). You need to shift quickly and decively otherwise you will get the grinding noise. Also it was difficult to know where and what gear you were in since there was not a really good detent feel. Mine was also stiff. I seem to recall that the loud thunk you get when going into and out of gear was due to the weight of the stainless prop that came with the 4 strokes. Used to annoy the heck out of me. My buddy had an older merc that ran great and never did that and he used to tease me about the money I spent and how his shifted so much more effortlessly. Good Luck, Alan
Marlin	posted 02-05-2008 08:24 PM ET (US) Yes, at least part of the thunk is supposedly due to the heavy stainless props. The Flo-Torq III hub is supposed to help alleviate that. I'm hoping to try one out this spring. -Bob
bigjohn1	posted 02-05-2008 11:42 PM ET (US) Without a doubt, switching to the Flo-Torq III hub will greatly improve the way this engine shifts and acts at low speed. Tom Clark recommended this to me and it really improved things. There is no “electronic switch” on your engine that switches cylinders off during shifting. The ECU computer will begin to shut down certain cylinders when you over-rev the engine but that’s an entirely different situation. If you don’t want to believe me, buy the official factory manual for your engine (not the puny little owner’s manual you got with the boat). It has a very detailed explanation of the ignition and fuel delivery systems and will explain things to very clearly.
montaukman	posted 02-06-2008 09:04 AM ET (US) Hi, I thought on the Merc 90 4 stroke, when you are running below a certain RPM, only some cylinders are working and once past that RPM you get the full power. I don't remember where I heard it but it sounds familiar to me. Alan
sosmerc	posted 02-09-2008 11:53 AM ET (US) Your 2005 90hp Merc 4 stroke runs on all 4 cylinders all the time. I have encountered the "shift problem" you describe on a number of my customer engines. Merc has addressed the issue on the very latest engines in that horsepower class by redesigning the shift mechanism inside the gearcase. According to my brief research, the changes cannot easily be made to older gearcases. The only thing that you can do to improve the quality of shifting on your motor is: make sure the engine is idling as slow as possible before attempting to shift from forward back to neutral. Install the latest model remote control with the Gen II low friction cables. Replace your lower unit with the newest version that has the new desmodronic shift system. Perhaps Merc will come up with some kind of "retro-fit" kit for older 4 stroke engines that experience the problem. The newer engines produce much more torque than the old 90 2 strokes at idle and this creates issues when trying to dis-engage the clutch. (the gearcase used on the early 4 stroke 75/90/115 is very nearly the same as the gearcase used on the 75/90 L3 2 stroke)
dbrown	posted 02-09-2008 09:06 PM ET (US) sosmerc, do you think switching to a different lubricant would help or is this strictly a mechanical problem? Oddly enough, my engine (90 FOURSTROKE) has the desmodronic shift system and it's still a bit fickle. I'm currently using the Merc. Premium. I was thinking of switching to the High Performance Gear Lube...
sosmerc	posted 02-10-2008 12:26 PM ET (US) dbrown...can you post your serial number? I'd like verify that you really do have the latest shift design. I do recommend the Merc High Performance gear lube, but I don't think it is going to make any difference with regards to this issue. I would disconnect the throttle and shift cables and see how much effort it takes to shift the engine manually back at the motor. It would be best to do this with the boat in the water. The engine needs to be warmed up and idling as slow as possible. I would also (with the cables still disconnected) shift the remote control through its full range...it should be very smooth and effortless. I have not yet had a chance to "play" with one of the very latest gearcases, but I am hoping to see a MAJOR improvement. (I'm hoping your engine isn't the latest design...I'd hate to find out that the "fix" hasn't been that successful). Please keep us posted. Thanks.
dbrown	posted 02-10-2008 03:14 PM ET (US) Thanks for the reply sosmerc. My serial number is 1B466307. What I have noticed is that the hard shifting is most prevalent when the boat is still moving at a small forward or backward motion, such as when docking or moving at idle speed in gear. It's then that you need to be more aggressive when pulling the control back to neutral. Not so much when the boat is totally stopped. Anything you can find out would be appreciated..
sosmerc	posted 02-10-2008 06:34 PM ET (US) Using your serial number I did verify that you have the newest gearcase design. Next I would ask specifically what control is used in your boat as well as the specific control cables. And what is your idle rpm after the engine is completely warmed up. Maybe in your case it is a rigging problem. How does it shift from forward to neutral with the engine OFF? (never attempt to shift from neutral to reverse without the engine running or someone turning the prop....neutral to forward and forward back to neutral with the engine off is ok) How long have you had this rig and has it ever been back to the shop for any adjustments? Was it a repower, or a new boat with matching new controls and rigging? I'm very interested in resolving this problem.
jimh	posted 02-10-2008 08:10 PM ET (US) In an earlier article I wrote about the change Mercury made to the shifting mechanism of their outboard motors in which they improved the mechanism by employing a desmodromic actuator. See: http://continuouswave.com/ubb/Forum1/HTML/015209.html In that article the 90-HP motors are mentioned, and the epoch of c.2005 is mentioned as when the desmodromic mechanism was introduced in that model. It is somewhat common that in high power motors an ignition interruption circuit is actuated during the shift process in order to momentarily reduce the torque produced by the motor and allow the gears to disengage more easily. This is seen on V6 motors in the 200-HP range. I have confidence in sosmerc's knowledge, and I would put more weight on his opinion (that such an ignition cut out is not employed on a 90-HP Mercury four-cycle motor with a Yamaha power head) than on the contrary opinion of your local mechanic. A lot of Mercury outboard engineering was revised during the period (2000 to 2005) when George Buckley was the CEO and he hired German auto engineer Claus Bruestle from Porsche to take charge of their four-cycle outboard motor development program. Claus told this anecdote about his experience with Mercury outboard motor shift mechanisms during an interview he gave when the Verado motor was being introduced: quote: When I joined Mercury, people were very nice to me and taught me how to drive and dock a boat. I remember one of my first experiences driving a boat, when I shifted and it made this great clunk. I said, "We are going to stop this—it sounds like a 1950s truck." People said, "Why? It's always been that way." I said, "Exactly." (The Verado motor, by the way, had a completely new design for the gear case and used electrical motors and actuators to accomplish the shifting. It shifts beautifully and without any KLUNK.) I think what you are experiencing in this particular motor is some of that Mercury engineering that was pre-Claus Bruestle. At the time your engine was being made, c.2005, Mercury knew it would be abandoning that design in the near future. In c.2007 Mercury replaced the Yamaha-Mercury 90-HP with the new Veradito model, based on the Verado block, which probably has a different gear case. Ultimately, both Buckley and Bruestle left Mercury. In all older outboard motors, part of the shifting process is learning how to shift in a manner that is most compatible with the particular gear case you are using. Most of them like quick, firm shifts which rapidly engage or disengage the gears. Being tentative with the shift mechanism does not lead to smooth shifts. In addition, if your cable mechanisms have any stretch or elasticity, or if your shifter lever and actuators are not properly aligned, you may have difficulty. Check the cables and the shift alignment to make sure all is well.
dbrown	posted 02-10-2008 08:37 PM ET (US) It shifts fine when the engine is off or when the boat is stationary and the engine is running. The engine idles right at 700 RPM's, which per the manual is correct. I bought the boat and motor new last April. It has been back for a starter replacement and at that time I had them check the linkage. They said is was correct and the shifting characteristics were normal. It has the standard cables and the Binnacle control MCC 4501..
OutrageMan	posted 02-10-2008 08:45 PM ET (US) Just a point of order. 1) Buckley was CEO of Brunswick, Pat Mackey is (was then) President of Mercury Marine. 2) Claus was hired by Fred Brightbill, then President of Mercury Outboard Division (he and Claus were the chiefs responsible for Verado). Of all of those people, Mackey is the only one left. Brian
sosmerc	posted 02-11-2008 11:20 AM ET (US) Just for clarification...dbrown's motor is the latest Verado-based 4 cylinder 90hp 4 stroke and it uses the latest design shift system (desmodronic). I have not had my hands on one of these yet, but I would bet that there is a switch associated with the shift arm that basically tells the engine computer when the engine is in neutral and when it has shifted. I do not call it a "shift switch" simply because it does not have any effect on shift effort. The engine has "overspeed" protection in neutral...and the engine computer needs to know when the motor is in neutral. radgroup (that started this thread) has the older design 90hp 4 stroke and his gearcase is the older design. I really don't recall if it has a shift activated switch or not, but if it does it most likely functions the same as the Verado-based system.
sosmerc	posted 02-11-2008 11:30 AM ET (US) dbrown...your MC 4500 control should be a Gen II control and thus uses the low friction Gen II cables. You might check to see that the cables have at least a couple of feet of unrestricted routing behind the box. (the cables MUST be free to move) Make sure they are not tie-wrapped together or to anything else for the first couple of feet after they come out of the control. I guess it is a judgement call on your part as to whether or not you have a problem. If the shifting effort takes away from your pleasure or causes any safety issues (such as your ability to dock or get the boat easily on the trailer) I would get the dealer to take a closer look.
sosmerc	posted 02-11-2008 01:07 PM ET (US) radgroup...what is your serial number? (I don't think your engine has any switch associated with your shift system, but I would like to confirm that)
dbrown	posted 02-11-2008 02:02 PM ET (US) Thank you sosmerc for looking into it. This is only my second Merc.(I had an older 67' model 650 that, by the way, shifted like a dream) and I guess I was expecting ths one to be better than it is. Before I bought this engine, I had the opportunity on many occasions to drive a boat with an older (late 90's model) Merc. XR6 and it had the same characteristics, but also had what I thought was an enormous clunk when shifting into gear. I spoke at length with the dealer about this concern before I bought and was assured that the new models had addressed that problem. On the bright side, mine just has a very small thud when engaging forward or reverse. Also, having had many Johnson/Evinrudes for the past 20 years, maybe I'm just spoiled by their buttery smooth shifting. I will look into the cable routing and let you know if I find any problem there...
sosmerc	posted 02-11-2008 03:12 PM ET (US) As mentioned before, the Merc FloTorq III hub will reduce the "clunk" and clutch rattle, but not the ease or effort of shifting.