I just picked up a 2012 Checkmate Pulsare 2100BR with a Merc 250 Optimax PROXS. Running a 24" SS prop, only 85 hours, I noticed a weird vibration at low speeds, it smooths out as I throttle up. I've owned other big Mercs that felt a bit like this too. I am still curious if anyone's nailed down the exact cause?
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low-speed vibration on my 2012 Merc 250 Optimax
- Thread starter H20 Guy
- Start date
WaterGambit
Member
- Joined
- Jun 16, 2025
- Messages
- 6
I've heard something similar from my network and they said the low-speed vibration with a big Opti is just a common characteristic.
One guy explained it has something to do with the firing order and the way the direct injection works at lower RPMs but it tends to smooth out when the engine's under load.
If you've already checked your prop for dings and balance, and the motor mounts seem solid, it's likely just part of the package.
One guy explained it has something to do with the firing order and the way the direct injection works at lower RPMs but it tends to smooth out when the engine's under load.
If you've already checked your prop for dings and balance, and the motor mounts seem solid, it's likely just part of the package.
I think what youre describing is pretty common on big Mercs at low RPMs, often its just the prop or shaft alignment causing minor vibration that smooths out as speed and load increase. It's usually not a sign of anything serious, but checking prop balance and engine mounts can help rule out anything that might worsen over time.