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post #7 of Old 07-21-2011
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Multiple Mount Failures

How are your mounts failing? Did the stud break? Or, was it a rubber failure?

We have twin Yanmar 4Jh4E motors. All four mounts failed on the port engine last weekend. The studs sheared off just inside the bottom thread on the lower adjusting nut. We were underway, and with the motor free to move since all four mounts were broke, lots of water came into the engine room real fast through the so-called drip-less shaft seal- thank God for twin pumps and a good crew with buckets. The front outboard mount on the starboard engine is also broken; the other three are not. The nut on the engine mount is resting on top of of the broken-off stud in the mount, off-set by about the diameter of the stud. If I continued to operate the engine, I'm sure the other three mounts would fail, in a cascading-type failure, since the remaining mounts would be overloaded.

I agree with the previous post concerning the mounts being aligned with each other. Some basic measurements should provide insight into the relative mount alignment. On a 4Jh4E, the stud-to stud center line athwart-ship distance is 470 mm (18.5"); the fore-aft distance is 506 mm (19.9"). I plan to make some measurements this weekend
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