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350 mag Engine noise

J

Jfer112

New member
Please help can anyone tell me what is causing this noise, it started after i changed the oil i used mercury 25w40 thats what was given to me at the shop, the engine has 151 hrs on it. Link to video at bottom Thank you.

 
Sounds like rod end.

I know of many engines with this issue that were driven/used for thousands of miles. However, on a marine engine you should get it fixed soonest.
 
Jfer112 said:
Theres oil coming out it made a mess as i was trying to adjust the valves, the oil pressure bounces between 45 .4 to 49 .7
Click to expand...

While adjusting dynamically is very accurate, it can be messy.
You may want to try using the 8 stop static adjustment procedure.
Start with #1 cylinder @ TDC C/S and adjust both #1 int/exh as per OEM specs, and then go right on down the firing order one cylinder at a time.
Keep in mind that you're ultimately setting the depth of the cam follower's hydraulic plunger.

This is a tried and proven procedure. When done correctly, you should not need to go back through them dynamically.



As for the noise.... use the P of E...... process of elimination.



.
 
Last edited:
And disrespectful spew continues, with cartoons no less. Misguided advice for valve lash adjustment "it can be messy", me thinks that the original poster alluded to already experiencing that. Missing the noise question altogether. More uselessness!
 
I believe he means that one of your piston connecting rods is a knocking........
But it is all a guess...........your video is not very good.

I would redo it keeping the camera stationary in one place where the noise is the loudest.

Also Chris suggested eliminating the belt so no accessories are being driven to eliminate them from the noise equation.
 
Remember in The Grapes of Wrath when they had to pull out a piston and replace it? Sorta the same deal for you. Repair would require removing the engine, taking off the intake, cylinder heads and oil pan. The offending rod and piston assembly is removed, fit with new bearing shells, and then the whole mess gets put back together and put back in the boat.
Common wisdom says that going to this much trouble for one piston is not cost effective and that a reconditioned engine should be installed. If it is indeed a bad rod, then you should consult with a marine mechanic and weigh the options.
 
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