Any Beneteau 351 or related, owners have any experience with an engine that "jumps" when put in reverse? Even at low RPMS, on several occasions the engine jumps so much that the binnacle shakes. My cutlass bearing is being replaced but the yard is aslo suggesting new engine mounts. Previous owner mentioned that he had the mounts replaced, but the yard claims they are the wrong size. If anyone has had such an issue, I would welcome hearing about it. David
Beneteau engine jumping in reverse
- Thread starter David21341
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Take hold of the engine with both hands
when it is shut down and try to rock or shake it. What you discribe seems to me to indicate that something has gone adrift. If the engine mounts are good you should be able to move the engine a little against the rubber cushions but it shouldn't feel the least bit sloppy.
when it is shut down and try to rock or shake it. What you discribe seems to me to indicate that something has gone adrift. If the engine mounts are good you should be able to move the engine a little against the rubber cushions but it shouldn't feel the least bit sloppy.
"Claims" of wrong size should get you thinking
about why they are saying that. You personally need to find out. If you know the engine model # and the type of mounts, that would be helpful information for anyone to help you to determine if they are indeed wrong, or if they are right and the yard simply wants more of your $$.
There are lots of things for you to check in addition to the cutless bearing, and what makes you think that needs replacing? Have you checked the flange coupling between the transmission and the shaft? Rumbling as you described sometimes come from loose bolts at the connection. I've had two of them get loose on me and replaced them but the vibration was horrendous. Do some checking on your own before you spend any money. A lot of checking.
about why they are saying that. You personally need to find out. If you know the engine model # and the type of mounts, that would be helpful information for anyone to help you to determine if they are indeed wrong, or if they are right and the yard simply wants more of your $$.
There are lots of things for you to check in addition to the cutless bearing, and what makes you think that needs replacing? Have you checked the flange coupling between the transmission and the shaft? Rumbling as you described sometimes come from loose bolts at the connection. I've had two of them get loose on me and replaced them but the vibration was horrendous. Do some checking on your own before you spend any money. A lot of checking.
Motor mounts
The first thing I would check is your idle speed. If it's too high it will cause the motor to jump when you place it in gear. If that check's out OK then I'd check the motor mounts next. I have a 361 that had faulty front motor mounts due to issues when they were cast. Westerbeke covered the entire repair without cost to me. Unfortunately whoever the guy was who replaced them over torqued one of the bolts that attached it to the face of the motor, which later showed up with the same symptoms you describe. Every time I'd drop it into gear it would jump. Additionally I could feel vibration where I hadn't before. What I found was not only did the mount shift downwards the adjusting nuts also moved out of position. Ultimately I did the engine to drive shaft realignment which solved the problem. BTW Westerbeke recommends checking/performing the shaft alignment on an annual basis as the rubber in the motor mounts does wear away under normal conditions causing the motor to shift position, if only slightly. If you do the alignment check you'll also get to check the flange coupling as Stu recommended. Good luck Mike
The first thing I would check is your idle speed. If it's too high it will cause the motor to jump when you place it in gear. If that check's out OK then I'd check the motor mounts next. I have a 361 that had faulty front motor mounts due to issues when they were cast. Westerbeke covered the entire repair without cost to me. Unfortunately whoever the guy was who replaced them over torqued one of the bolts that attached it to the face of the motor, which later showed up with the same symptoms you describe. Every time I'd drop it into gear it would jump. Additionally I could feel vibration where I hadn't before. What I found was not only did the mount shift downwards the adjusting nuts also moved out of position. Ultimately I did the engine to drive shaft realignment which solved the problem. BTW Westerbeke recommends checking/performing the shaft alignment on an annual basis as the rubber in the motor mounts does wear away under normal conditions causing the motor to shift position, if only slightly. If you do the alignment check you'll also get to check the flange coupling as Stu recommended. Good luck Mike
Beneteau Engine shake
I had a similar problem on my 331, but it was new so I knew it was not the vibration isolators, (motor mounts). Mine would jump when I backed up and put the engine in Reverse or Forward. Turns out the idle was set to low. Your Yanmar should idle at approx 900 RPM. Adjusted the idle and no more jumping!( Incidently I did not think of this by myself, my Beneteau dealer told me when I described the problem to him). He came out and adjusted it showing me what to do. The next time, I adjusted it myself with my wife on the helm. (The throttle cable will expand and contract due to heat and cold.) Hope this helps!
I had a similar problem on my 331, but it was new so I knew it was not the vibration isolators, (motor mounts). Mine would jump when I backed up and put the engine in Reverse or Forward. Turns out the idle was set to low. Your Yanmar should idle at approx 900 RPM. Adjusted the idle and no more jumping!( Incidently I did not think of this by myself, my Beneteau dealer told me when I described the problem to him). He came out and adjusted it showing me what to do. The next time, I adjusted it myself with my wife on the helm. (The throttle cable will expand and contract due to heat and cold.) Hope this helps!
Yeah, could be ...
Sounds like you have a fluid drive. RND is the basic shift pattern, eh right? Okay if so, you probably have a Borg Warner Velvet drive transmission. Nice reliable tranny. Very simple and very durable. The shift selector is detented on a ball bearing spring loaded to holes drilled in the selector plate. Probably the weakest point of this unit. Reason being is, if the linkage adjustment isn't 'length related' to the shift selector then the ball detent isn't quite seated into the selector hole and thus can vibrate off position. Since this selector plate is bolted on the valve body spool, it may find control pressures high enough to pop it into reverse. Reason being is reverse is the highest pressure circuit in this tranny, and so form follows fashion so to speak. The highest fashion of force will steer the valve spool in the direction. And of course, my guess is reverse. Not that I have seen this happen, but I have bench dyno'd these transmissions and have known the shift plate to glide into that position if undetented from neutral. Playing around with such units I found drive will tend to exert a bit of pressure on the neutral side of the shift plate. Oh well, what I would do is to check the shift selector position against the shift plate position at the tranny, making certain both ends agree, in that bothe ends are dead on the selection anticipated. Should be a simple and easy check. sardo
Sounds like you have a fluid drive. RND is the basic shift pattern, eh right? Okay if so, you probably have a Borg Warner Velvet drive transmission. Nice reliable tranny. Very simple and very durable. The shift selector is detented on a ball bearing spring loaded to holes drilled in the selector plate. Probably the weakest point of this unit. Reason being is, if the linkage adjustment isn't 'length related' to the shift selector then the ball detent isn't quite seated into the selector hole and thus can vibrate off position. Since this selector plate is bolted on the valve body spool, it may find control pressures high enough to pop it into reverse. Reason being is reverse is the highest pressure circuit in this tranny, and so form follows fashion so to speak. The highest fashion of force will steer the valve spool in the direction. And of course, my guess is reverse. Not that I have seen this happen, but I have bench dyno'd these transmissions and have known the shift plate to glide into that position if undetented from neutral. Playing around with such units I found drive will tend to exert a bit of pressure on the neutral side of the shift plate. Oh well, what I would do is to check the shift selector position against the shift plate position at the tranny, making certain both ends agree, in that bothe ends are dead on the selection anticipated. Should be a simple and easy check. sardo
Yanmar?
David: If you have a Yanmar, this is a common problem when replacing motor mounts. Some think that you can go cheap and get the same performance as the OEM mounts. Everyone that has Yanmar training will tell you that it is important to use the same mounts that Yanmar recommends. They have different mounts for the fore/aft positions. There is also a difference in the density of the rubber on these units too. The idle may also be a problem, but I would suggest that someone takes a look at your cable and the adjustment too. I would do everything that is cheap before I would start changing anything.
David: If you have a Yanmar, this is a common problem when replacing motor mounts. Some think that you can go cheap and get the same performance as the OEM mounts. Everyone that has Yanmar training will tell you that it is important to use the same mounts that Yanmar recommends. They have different mounts for the fore/aft positions. There is also a difference in the density of the rubber on these units too. The idle may also be a problem, but I would suggest that someone takes a look at your cable and the adjustment too. I would do everything that is cheap before I would start changing anything.
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