Hi all,
I have a Mariner 50hp from 1995 and I have trouble finding why I have got this noise coming through the midsection. It's been like that for quite some time but has been quite noticeable for the past couple months. it sounds like bearing going off.
What I did:
. Removed the leg and ran the engine without the leg (plugged water inlet so that I could get water run into the cooling system) - No significant noise of bearings.
. Bought a second hand gearbox, serviced it - thinking that it could have been the bearing from the gearbox. Still the same.
. Bought a stethoscope, The noise only comes from the midsection. Checked around the crankshaft/ gearbox, I don't have bearing noise (apart from engine noise).
My hypothesis:
. Corroded exhaust tube around the midsection - No more soundproof of the driveshaft due to the corrosion.
. Exhaust tube vibrating onto the midsection.
Here is a video of the noise I am talking about: (check at 6 seconds)
https://www.youtube.com/watch?v=cdbEvyNzX6c