I’ve got a 1990 40hp 4cyl 2-Stroke
the boat was last in the water 3 years ago and due to circumstances I’ve not had time for boating until this year so have dusted it off to get going for this season.
the last season I had the boat in the water it started making a deep bassy beating noise while underway. It was a persistent with the rpm and seemed to be in relation to how much load it was under. Wouldn’t do it while reviving in neutral though. This really concerned me and probably part of the reason I’ve not used the boat for so long.
My my initial thoughts were that he crank shaft bearings or something devastating like that was the issue but having read a few things I’ve absorbed the following:
when outboards produce a noise like this when at idle or revved in neutral it is most likely a power head issue crankshaft it similar.
But when symptoms only manifest under load - this then points towards the lower unit. Prop, broken gears etc. Prop is solid and I dings or dents. I’m going to change the LU oil at the weekend so will be looking for large metal pieces on the magnet of course.
after reading a few things I’ve come up with another possible cause. The last season I was using the boat my shift cable snapped - due to age and it was where it was curved at the transom area. I replaced it and I’m now thinking back, this was around the time this beating sound started? I’m wondering if I never setup the shift cable adjustment correctly and I might not fully be in forward gear.
does this sound at all plausible to anyone. Anyone have any experience with this?
boat not in the water yet as still fine tuning bits and pieces so cannot test the theory yet. Just want to know if it’s worth adjusting this?
thanks in advance
the boat was last in the water 3 years ago and due to circumstances I’ve not had time for boating until this year so have dusted it off to get going for this season.
the last season I had the boat in the water it started making a deep bassy beating noise while underway. It was a persistent with the rpm and seemed to be in relation to how much load it was under. Wouldn’t do it while reviving in neutral though. This really concerned me and probably part of the reason I’ve not used the boat for so long.
My my initial thoughts were that he crank shaft bearings or something devastating like that was the issue but having read a few things I’ve absorbed the following:
when outboards produce a noise like this when at idle or revved in neutral it is most likely a power head issue crankshaft it similar.
But when symptoms only manifest under load - this then points towards the lower unit. Prop, broken gears etc. Prop is solid and I dings or dents. I’m going to change the LU oil at the weekend so will be looking for large metal pieces on the magnet of course.
after reading a few things I’ve come up with another possible cause. The last season I was using the boat my shift cable snapped - due to age and it was where it was curved at the transom area. I replaced it and I’m now thinking back, this was around the time this beating sound started? I’m wondering if I never setup the shift cable adjustment correctly and I might not fully be in forward gear.
does this sound at all plausible to anyone. Anyone have any experience with this?
boat not in the water yet as still fine tuning bits and pieces so cannot test the theory yet. Just want to know if it’s worth adjusting this?
thanks in advance