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Drive knocks or vibrates

Knocking or vibration at the stern? Listen in neutral first. If you hear the noise there too, it comes from the engine, the belts or the mounts. If you only hear it in gear, it is the propeller, the U-joints, the gimbal bearing or the drive gears.

Check step by step

Select your engine on its model page to see the relevant steps and part numbers.

  1. DIY

    Listen for when the noise occurs: in neutral, only in gear or only when you turn. Do this carefully and without loading the drive more than necessary.

    The noise can come from the engine mounts, the propeller, the universal joints, the driveshaft bearing or the internal parts of the drive. When you hear it tells you a lot about where it is. A noise that only appears when turning points to the joints.

    Action: Note when the noise occurs and tell the workshop. Don't run repeated tests to provoke a metallic noise, as a damaged part can then fail completely.

  2. DIY

    With the engine off, check the propeller blades for bends and nicks, and turn the propeller to feel whether the hub is slipping.

    A bent or damaged propeller and a damaged hub are common causes of vibrations felt throughout the boat.

    Action: Remove the key before you touch the propeller. A damaged propeller is repaired or replaced by a propeller shop, and that should be done before any drive parts are replaced.

  3. Workshop

    Check the engine mounts and their bolts. Is the rubber cracked, or are the bolts to the engine bed loose?

    Worn engine mounts cause vibrations that feel as if they come from the drive.

    Action: Inspect with the engine off. Never loosen load-bearing mounts yourself. The workshop replaces them and aligns the engine with the drive.

  4. Workshop

    Does the noise seem to come from the engine? Check the belts and rock the pulleys with the engine off.

    A loose belt or a pulley with a worn bearing rattles and can sound like the drive.

    Action: Tension the belt as described in the manual. Play in a pulley needs fixing at a workshop.

    V-belt
  5. Workshop

    If the propeller, mounts and belts are in order, that leaves the universal joints, the gimbal bearing, the bellows and the internal parts of the drive. Those are workshop jobs.

    The U-joints, gimbal bearing and gears can only be reached by removing or opening the drive. The bellows, clamps and gimbal bearing are inspected by the dealer.

    Action: Let the workshop find the fault before you order parts. A new bellows won't stop a knocking bearing.

    bellowsseal kit

When to call a workshop

Call a workshop if new metallic noises come from the drive, if the boat doesn't move even though the engine is running, or if the drive is stiff to turn. Don't keep running. Tell them whether the noise started after a grounding, a propeller change or other work.

Frequently asked questions

There's a metallic knocking from the upper unit of the DP drive, even in neutral. What's wrong?

A metallic knock from the upper unit, even in neutral, usually comes from a bearing or a gear in the drive, but which one only becomes clear when the drive is opened. Stop test running and let the workshop remove the drive.

The engine runs but the drive gives no thrust and the shift lever clicks. Can I keep going?

No. If the control lever clicks but no power reaches the propeller, the gear is not engaging, in the control, the cable or the drive. Have a workshop inspect the drive and controls before you load the drive again.

Related troubleshooting

Sources

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