2003 Mercuiser 350 MAG MPI

[Sea N Sun]

Hello

A few days ago my engine started making noise when it started, this noise has decreased a little now however when I took the boat out and was in gear will not go over 3000 rpm and the engine will vibrate a lot.

Any idea what the problem is?

 

[Bondo]

Re: 2003 Mercuiser 350 MAG MPI

Ayuh,... Welcome aboard,....
At this point, with the Info provided,...
I'd say you need a Mechanic....

 

[Sea N Sun]

Re: 2003 Mercuiser 350 MAG MPI

Hi

Since last time I had a mechanic look at the boat and he told me that may be a connecting rod or a wrist pin however to be sure he wants to take the drive out and check the engine again.
I have by now done compression test and all cylinders have 190 to 200 psi.
I clean the spark plugs and distributor cap, had the fuel/water filter changed, open the valve cover no water in the oil, no water in the cylinders and yesterday I took the boat out of the water and checked the drive oil no water or any metal there.
During the drive yesterday to take the boat out the noise was still there however the rpms increased over 3000 to 4000 and the boat increased speed no problem however I did not want to push the engine and I just did this for a minute or two.
Any advice as to what is happening. I also listen to the engine with a stethoscope and the noise appears o come from the back port side. The engine only has 140 hours.

Thank you
John