Among the engine problems I have been having lately, one was a vibration at low rpm's. Yanmar sent a tech over to check out the vibration (among other things) and he found one of the mounts to be "bottomed out." On further inspection he noticed that the port side mounts were 150's and the starbored side mounts were 100's. These numbers apparently represent load capability. He had never seen differential mounts set up side to side and was sure they should be set up for differential loads fore and aft. All this was discovered after hours, so we didn't have anybody to call... does anybody know if this is the correct mounting? (H380 3JH3E) Brian
Engine mounts
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Someone Goofed
Someone goofed. You're correct, they should not be matched up on the same side. Don't have my shop manual here but I believe the larger numbers go forward which may seem counter-intuitive as you'd think the transmission would add more weight. It's been a long time since I looked at this but I remember the counter-intuitive part. Someone correct me if I'm wrong. Correct - the numbers do represent load - Kilograms? (I know it's metric). Ditto the above paragraph.
Someone goofed. You're correct, they should not be matched up on the same side. Don't have my shop manual here but I believe the larger numbers go forward which may seem counter-intuitive as you'd think the transmission would add more weight. It's been a long time since I looked at this but I remember the counter-intuitive part. Someone correct me if I'm wrong. Correct - the numbers do represent load - Kilograms? (I know it's metric). Ditto the above paragraph.
That was quick
Wow.. I put in a call to the dealer. I will be interested to hear what they have to say. Thanks Brian
Wow.. I put in a call to the dealer. I will be interested to hear what they have to say. Thanks Brian
John is correct.
I spoke with the folks at Mac Boring (Yanmar parts and repair servicers) and they told me the front mounts were the heavier ones. ~ Happy sails to you ~ _/) ~
I spoke with the folks at Mac Boring (Yanmar parts and repair servicers) and they told me the front mounts were the heavier ones. ~ Happy sails to you ~ _/) ~
Mount technical data
Gentlemen, I will refer you to the Yanmar Marine Engine Installation Manual- Version IV. Pages 11-1-1 through 11-2-30 will keep you informed of your questions. Generally the Yanmar engine does have offset mounts on the larger engines. The installation described by Brian is in fact very correct. Page 11-2-30 of the installation manual shows "considerations for engine installation" on the 3JH3E Yanmar marine engine. Engine construction, starter positions, alternators and other weight distributions will determine engine mount locations. Most Yanmar engine owners have never seen or heard of the Yanmar Engine Installation Manual. It covers more ground than has ever shown up in this forum during its life time. I suggest you obtain a copy for winter reading. Did you know that those engine mounts have torque specs for securing following engine alignments?
Gentlemen, I will refer you to the Yanmar Marine Engine Installation Manual- Version IV. Pages 11-1-1 through 11-2-30 will keep you informed of your questions. Generally the Yanmar engine does have offset mounts on the larger engines. The installation described by Brian is in fact very correct. Page 11-2-30 of the installation manual shows "considerations for engine installation" on the 3JH3E Yanmar marine engine. Engine construction, starter positions, alternators and other weight distributions will determine engine mount locations. Most Yanmar engine owners have never seen or heard of the Yanmar Engine Installation Manual. It covers more ground than has ever shown up in this forum during its life time. I suggest you obtain a copy for winter reading. Did you know that those engine mounts have torque specs for securing following engine alignments?
JB, I would like to know WHY Yanmar engineers
its' mounts as it does. Anything in the manual that explains the need for different size and weight capacities? Do they explain their torque specs or is that one of those 'idiot specs'? You know, they think they have to give a 'value' or somebody will leave 'em loose. The reason I ask is because, like many original equipment parts, after my rebuild of our H34, the engine mounts are landfill. I replaced them with aluminum mounts that are much smaller. They are rated for more weight capacity each, than the total engine weight. They allow me to run stuff like a hydraulic pump for my primary winch conversion. And the total price for four of them? Less than $100.00. And they work great. The engine doesn't dance around and is smooth at all operating speeds. I have never understood why a Yanmar should dance around so much especially at startup or shutdown. There are glimpses of my new mounts in several pictures on my web site.
its' mounts as it does. Anything in the manual that explains the need for different size and weight capacities? Do they explain their torque specs or is that one of those 'idiot specs'? You know, they think they have to give a 'value' or somebody will leave 'em loose. The reason I ask is because, like many original equipment parts, after my rebuild of our H34, the engine mounts are landfill. I replaced them with aluminum mounts that are much smaller. They are rated for more weight capacity each, than the total engine weight. They allow me to run stuff like a hydraulic pump for my primary winch conversion. And the total price for four of them? Less than $100.00. And they work great. The engine doesn't dance around and is smooth at all operating speeds. I have never understood why a Yanmar should dance around so much especially at startup or shutdown. There are glimpses of my new mounts in several pictures on my web site.
Yamar Shock Mounts
I am not a Yanmar engineer so I cannot give you a complete answer. I can provide some information that relates to your question. The Yanmar flexible engine mount is designed to make the vibration transmission rate (engine amplitude rate) small in the engine's operational range. The idea is to reduce hull vibration to a maximum 80db level. This is the same level of vibration present in a passenger car. At the resonance point, which is encountered at both engine starting, low rpms and stopping, the amplitude may be large, but the mode of vibrations as such times is rolling, centered around the propeller shaft(engine dancing around). The upper part of the engine may be vibrated to a certain degree, but there is almost no vibration transmitted to the propeller. The torque specs are determined as in standard engineering practices. They need to be tight enough to prevent predetermined engine vibration and resonance from loosening the fasteners during working loads, but not so tight as to over stress the fastener and create failure. The shock mount values are determined by the elasticity of the rubber. That varies in each different mount. The loading of the rubber determines where the propeller will exit the hull centered in the shaft log. The design of the hull and the engine weight distribution during operation will determine the size of the shock mount. I deal with these engines on a daily basis from those in warranty to those that have been around for many years. One can violate every Yanmar recommendation in the books and the engine will operate. The final determination - How soon will one have a premature failure or have to overhaul as opposed to the projected normal life of the engine? Professionals follow the books and specs. Engineers have designed the engine and provided the information that will provide the longest life for their product. They are not sales people and they haven't any idea of retail sales prices for replacement parts.
I am not a Yanmar engineer so I cannot give you a complete answer. I can provide some information that relates to your question. The Yanmar flexible engine mount is designed to make the vibration transmission rate (engine amplitude rate) small in the engine's operational range. The idea is to reduce hull vibration to a maximum 80db level. This is the same level of vibration present in a passenger car. At the resonance point, which is encountered at both engine starting, low rpms and stopping, the amplitude may be large, but the mode of vibrations as such times is rolling, centered around the propeller shaft(engine dancing around). The upper part of the engine may be vibrated to a certain degree, but there is almost no vibration transmitted to the propeller. The torque specs are determined as in standard engineering practices. They need to be tight enough to prevent predetermined engine vibration and resonance from loosening the fasteners during working loads, but not so tight as to over stress the fastener and create failure. The shock mount values are determined by the elasticity of the rubber. That varies in each different mount. The loading of the rubber determines where the propeller will exit the hull centered in the shaft log. The design of the hull and the engine weight distribution during operation will determine the size of the shock mount. I deal with these engines on a daily basis from those in warranty to those that have been around for many years. One can violate every Yanmar recommendation in the books and the engine will operate. The final determination - How soon will one have a premature failure or have to overhaul as opposed to the projected normal life of the engine? Professionals follow the books and specs. Engineers have designed the engine and provided the information that will provide the longest life for their product. They are not sales people and they haven't any idea of retail sales prices for replacement parts.
JB, Thank you very much. Good post.
I have been an avid boater since the sixties and a hot rodder even longer. The hot rod part of me has always led me to question the Yanmar mount setup. In hot rodding, (I've said this here before) there are as many different ways to mount an engine into a vehicle as there are engines and vehicles. The only thing that counts is the anticipated use of the setup, not longevity. After all, we are talking about engine mounts, not pistons for Gawd sakes! So JB, thanks for the scoop, I rest easy.
I have been an avid boater since the sixties and a hot rodder even longer. The hot rod part of me has always led me to question the Yanmar mount setup. In hot rodding, (I've said this here before) there are as many different ways to mount an engine into a vehicle as there are engines and vehicles. The only thing that counts is the anticipated use of the setup, not longevity. After all, we are talking about engine mounts, not pistons for Gawd sakes! So JB, thanks for the scoop, I rest easy.
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