Issues with Mercury 150 4 Stroke

[jmzubris]

Looking for some advice on what to do with this motor. I am currently running a 2012 Mercury 4 Stoke on a z18. Motor has 220 hours and was maintained regularly. Running at around 5700 rpms I noticed a loud banging from the upper engine. Powered down immediately and got towed to a nearby ramp. Compression is fine but my oil was very thin and my mechanic believes its a bearing issue, possibly damaging the entire powerhead? Has anybody been in a similar situation?

 

[Larry Williams]

not heard of this problem- please keep us posted as you learn more about the problem. Thanks

 

[JohnB]

Just a few weeks ago my buddy’s Yamaha did something very similar. At first, the dealer thought bearing, too. However it turned out to be a sheared flywheel key. When it was all said and done, it was only $234… which pales in comparison to the cost of a rebuild.

 

[jerry shack]

Looking for some advice on what to do with this motor. I am currently running a 2012 Mercury 4 Stoke on a z18. Motor has 220 hours and was maintained regularly. Running at around 5700 rpms I noticed a loud banging from the upper engine. Powered down immediately and got towed to a nearby ramp. Compression is fine but my oil was very thin and my mechanic believes its a bearing issue, possibly damaging the entire powerhead? Has anybody been in a similar situation?

The first thing I would look at is the oil for any metallic shavings or a shining in the oil when looking at it in the sun light that would be bearing material
The oil is thin any ways 0W-20 and 5W-30 Easy way to tell if it is a rod (not to tell your mechanic his job) bring each piston to the top and just before the piston goes back down there is a 2 degree swing where the crank moves but the piston does not. at that point the load is off the piston that's when you get a screw driver and thru the spark plug hole and see if the piston moves when you push on it. You will have to do each cylinder to find the bad one even if there is one. Sometimes when a fuel pump spring breaks it will cause a knocking noise. Or JohnB is right.