1. Yanmar diesel vibrates excessivelyat lowest idle, but not at higher RPM's. Have been told I have to replace engine mounts? Do I? Motor mounts were stretched when a rope entangled around propeller shaft between the prop and the shaft support. Has any one changed the motor mounts on an 18 hp, fresh water cooled Yanmar diesel? Can it be done without removing engine? 2. Whenever I turn on the key, the red indicator light on the far right of the engine control panel in the cockpit comes on, but quickly goes out when the engine comes on. According to the literature I have it indicates low pressure. Low pressure what? 3. The engine control panel in the cockpit has to be replaced. Who is manufacturer, and where can I get a replacement? Looking forward to your replys and thanks for your help.
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Yanmar Engine Vibrations
Harry, All Yanmars vibrate at different rpms. I have a 35 hp fresh water cool Yanmar on my Hunter Legend 37 that is smooth as silk at 2300 rpms, loud and shaky at 1000 rpms, fairly smooth at 2500 rpms. Sometimes i feel the shaft will vibrate to pieces. I did ,however, discover that keeping my stuffing box and my cutlass bearing very new and tight greatly reduced the vibrations. Alignment of course is everything. Make sure your shaft is properly aligned to the engine coupling. Good Luck, Barrie
Harry, All Yanmars vibrate at different rpms. I have a 35 hp fresh water cool Yanmar on my Hunter Legend 37 that is smooth as silk at 2300 rpms, loud and shaky at 1000 rpms, fairly smooth at 2500 rpms. Sometimes i feel the shaft will vibrate to pieces. I did ,however, discover that keeping my stuffing box and my cutlass bearing very new and tight greatly reduced the vibrations. Alignment of course is everything. Make sure your shaft is properly aligned to the engine coupling. Good Luck, Barrie
Harry, Without more info on the circumstances
of your rope/prop encounter and the resulting damage, motor mounts might not be the problem, or only part of it. Unless you are a fairly good mechanic and understand the alignment, balancing and runout/clearance conditions required to check out your drivetrain I would suggest; 1. Having such a person survey this area of the boat and recommend a course of repair. This person would not be the one repairing the boat. 2. Check with your insurance broker to see if this accident is covered by your policy. 3. Having the control panel also looked at. Changing out an electronic and mechanical control center can be very, very expensive, complicated and ultimately life threatening should it fail at sea due to faulty or slipshod repair. Good luck, as this is a fairly large undertaking. Ray S/V Speedy
of your rope/prop encounter and the resulting damage, motor mounts might not be the problem, or only part of it. Unless you are a fairly good mechanic and understand the alignment, balancing and runout/clearance conditions required to check out your drivetrain I would suggest; 1. Having such a person survey this area of the boat and recommend a course of repair. This person would not be the one repairing the boat. 2. Check with your insurance broker to see if this accident is covered by your policy. 3. Having the control panel also looked at. Changing out an electronic and mechanical control center can be very, very expensive, complicated and ultimately life threatening should it fail at sea due to faulty or slipshod repair. Good luck, as this is a fairly large undertaking. Ray S/V Speedy
18 HP Vibration
I have a 18 HP Yanmar on my 320, and it vibrates very badly below 800 RPM. Once up to speed, it does OK. A quick question: Does the vibration go away under load, or is it only evident when the engine is not in gear? If it exists only when in gear, then it can be something related to rope around the shaft, IE: shaft, prop, or bearings. If the vibration goes away under load (read in gear) then it could be the motor mounts. If it vibrates in forward, and not reverse, then that might clue you in to which motor mount it is. When the suspect mount is compressed, the vibration would go away, but when stressed, it would vibrate more. You might also look for the rubber particles around a mount. I tighted up the lag bolts on my mounts, and that seemed to help my vibration, but not entirely. Remember that the lag bolts go into raw wood, and should have a sealant placed in the hole if you remove one of the bolts. If the motor mounts are moved or replaced, you will need to align the motor to the shaft. If you replace mounts, make sure you replace them in pairs, front and aft. The procedure should be in the book, at least it is in mine. I haven;t done it yet, but will in the sring when the boat is placed back in the water. It doesn't look too hard, just muscle and a feeler gage. Good luck.
I have a 18 HP Yanmar on my 320, and it vibrates very badly below 800 RPM. Once up to speed, it does OK. A quick question: Does the vibration go away under load, or is it only evident when the engine is not in gear? If it exists only when in gear, then it can be something related to rope around the shaft, IE: shaft, prop, or bearings. If the vibration goes away under load (read in gear) then it could be the motor mounts. If it vibrates in forward, and not reverse, then that might clue you in to which motor mount it is. When the suspect mount is compressed, the vibration would go away, but when stressed, it would vibrate more. You might also look for the rubber particles around a mount. I tighted up the lag bolts on my mounts, and that seemed to help my vibration, but not entirely. Remember that the lag bolts go into raw wood, and should have a sealant placed in the hole if you remove one of the bolts. If the motor mounts are moved or replaced, you will need to align the motor to the shaft. If you replace mounts, make sure you replace them in pairs, front and aft. The procedure should be in the book, at least it is in mine. I haven;t done it yet, but will in the sring when the boat is placed back in the water. It doesn't look too hard, just muscle and a feeler gage. Good luck.
Not unusual.
Harry: I do not think that the rough at low RPM's is that unusual. I would think that your boat is getting to an age that the motor mounts may need to be looked at. Be sure that you use the Yanmar mounts and not the aftermarket ones. There have been several posts regarding this issue (check the archives). I recommend that you have a Yanmar service person check them out before you decide to swap them out. I think that the mounts run about $100/ea. So changing them if that is not the probelm is really not prudent. The control panel is a yanmar part. Why do you think it needs to be replaced. The cover/mounting plate can be replaced without the entire panel. We replaced our plate several years ago for about $35 or so. Ours was cracked because of the fuel shutoff control. That is why we moved ours down below. When you turn on your engine the panel goes through a diagnostics function. If you do not have any buzzers or lights on when the engine is running, I do not think that there is anything wrong. I believe that the pressure indicator is the Oil Pressure. Unless the engine is running you cannot tell if there is a low pressure situation.
Harry: I do not think that the rough at low RPM's is that unusual. I would think that your boat is getting to an age that the motor mounts may need to be looked at. Be sure that you use the Yanmar mounts and not the aftermarket ones. There have been several posts regarding this issue (check the archives). I recommend that you have a Yanmar service person check them out before you decide to swap them out. I think that the mounts run about $100/ea. So changing them if that is not the probelm is really not prudent. The control panel is a yanmar part. Why do you think it needs to be replaced. The cover/mounting plate can be replaced without the entire panel. We replaced our plate several years ago for about $35 or so. Ours was cracked because of the fuel shutoff control. That is why we moved ours down below. When you turn on your engine the panel goes through a diagnostics function. If you do not have any buzzers or lights on when the engine is running, I do not think that there is anything wrong. I believe that the pressure indicator is the Oil Pressure. Unless the engine is running you cannot tell if there is a low pressure situation.
Engine control panel
I have a 1987 Hunter 31. I found that my local Yanmar dealer has some of the control panels. I do not know what the problem is with your panel, but the one on my boat broke aroung the engine stop cable pull and I was able to repair it. I moved the cable pull below the panel and mounted it through the fiberglass under the panel. I then found a piece of black hard plastic (part of an old battery box) and trimmed a new piece of plastic to fit over the crack in the control panel. I then glued the plastic to the panel with black silicone sealer. This made it water tight and you cannot tell that it was ever broken. I hope this helps...
I have a 1987 Hunter 31. I found that my local Yanmar dealer has some of the control panels. I do not know what the problem is with your panel, but the one on my boat broke aroung the engine stop cable pull and I was able to repair it. I moved the cable pull below the panel and mounted it through the fiberglass under the panel. I then found a piece of black hard plastic (part of an old battery box) and trimmed a new piece of plastic to fit over the crack in the control panel. I then glued the plastic to the panel with black silicone sealer. This made it water tight and you cannot tell that it was ever broken. I hope this helps...
Other Engine Roughness Sources
A two cylinder engine will run rougher than a three or four cylinder engine. Valve adjustment could be a factor. Bleeding the engine might help and could be a cheap fix, especially for reducing low RPM roughness. If the roughness returns after bleeding then I'd suspect upstream air leaks. Caution: the screw on the top of the engine fuel filter tends to leak air (suction leak). Yanmar recommends the copper washer be replaced under the screw. I've used a very small amount of Permatex on the screw threads and that seems to work. If one of the fuel filters are getting plugged from contamination then this would increase the suction and could introduce air into the fuel system which would cause more roughness. Replace filters and tighten hose clamps. It's possible a fuel hose can develop a pinhole leak typically near a clamp or barb end. If the hose is long enough cut off the small section that fits over the barb and reclamp. The drive train (prop, shaft, zinc, etc.) can all cause balancing problems. There is one shop that advertises they balance fixed blade props, both dynamically and for pitch of the blades using an Australian machine. Their ads are probably in power boat magazines. The cast bronze prop that comes with the boat is roughly balanced at best. The zinc is a probable cause because it degrades unevenly. If your fuel tank is old and has never been cleaned that's another potential problem. Dirty fuel will tend to clog up the fiters quickly but I don't know if this would contribute to low RPM roughness.
A two cylinder engine will run rougher than a three or four cylinder engine. Valve adjustment could be a factor. Bleeding the engine might help and could be a cheap fix, especially for reducing low RPM roughness. If the roughness returns after bleeding then I'd suspect upstream air leaks. Caution: the screw on the top of the engine fuel filter tends to leak air (suction leak). Yanmar recommends the copper washer be replaced under the screw. I've used a very small amount of Permatex on the screw threads and that seems to work. If one of the fuel filters are getting plugged from contamination then this would increase the suction and could introduce air into the fuel system which would cause more roughness. Replace filters and tighten hose clamps. It's possible a fuel hose can develop a pinhole leak typically near a clamp or barb end. If the hose is long enough cut off the small section that fits over the barb and reclamp. The drive train (prop, shaft, zinc, etc.) can all cause balancing problems. There is one shop that advertises they balance fixed blade props, both dynamically and for pitch of the blades using an Australian machine. Their ads are probably in power boat magazines. The cast bronze prop that comes with the boat is roughly balanced at best. The zinc is a probable cause because it degrades unevenly. If your fuel tank is old and has never been cleaned that's another potential problem. Dirty fuel will tend to clog up the fiters quickly but I don't know if this would contribute to low RPM roughness.
oil light
that should be your oil pressure light, you should have an audio alarm that comes on too, when you turn the key on. you can get a panel from yanmar. your yanmar manual will tell you what each square is on the panel. low oil, low voltage, and overheating.
that should be your oil pressure light, you should have an audio alarm that comes on too, when you turn the key on. you can get a panel from yanmar. your yanmar manual will tell you what each square is on the panel. low oil, low voltage, and overheating.
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