Failed engine mounts: signs, age and what replacing marine engine mounts costs

Engine mounts hold the engine to its bearers and soak up its vibration with a block of rubber. The rubber wears out quietly. It hardens, cracks, swells with oil or tears away from its metal, and the first signs are rubber dust on the bearers and more shake than there used to be. Left long enough, the engine moves on its bed, the shaft goes out of line and the coupling, the cutless bearing and the gearbox pay for it.

How a surveyor checks them

Look at each mount. Practical Sailor's Marc Robic starts with two questions: is there rubber dust round the mounts, and is there abnormal engine vibration. Some dust after about 10 years is normal; a growing amount with vibration means the mounts are going. Look for cracks, rubber separating from the metal and oil soaking the rubber.

Power & Motoryacht gives a quick visual test: if the engine's bracket sits all the way down on the mount's stud, the rubber has lost its spring. Mounts sitting fairly high on the stud are fine. On the sea trial, watch the engine as it goes into gear: a corner that lifts or twists in reverse has a failed mount.

What decides the grade

A mount that's broken or separated, so the engine moves freely, is an A: alignment is gone and the next hard gear change can do real damage. Collapsed, oil-soaked or cracked rubber with heavy vibration is a B. Light dust on old mounts that are otherwise sound is a C to watch.

What replacement costs

Replace all four at once, both sources agree. Fix any oil leak first, or the new rubber goes the same way.

Photos to take

Each mount close up showing the rubber and the stud, any rubber dust on the bearer, any oil, and the shaft coupling. With Axsail, name the mount as you photograph it and the photo goes on its finding.

Writing it up

Name each mount by position, describe the rubber, how high the bracket sits on the stud, and whether the engine moves under load. Then the recommendation: all four, then alignment.