noise

[bones774]

I have been hearing noise at the rear of my engine, iI thought it was some type of rattling/banging driveline noise. As I got closer to engine bay for inspection I put my hand on the port side exhaust(the large metal pipe after the rubber connectors heading down and out) and felt the noise and vibration kinda coming from that pipe. Could there be something in that piupe thats loose or flapping?
I had the outdrive off this winter and the u-joints looked fine, so i didn't think it was them.
Any ideas,
thnaks

 

[Turn-n-Burn]

Re: noise

sounds like your water shutters.....

 

[bones774]

Re: noise

I'm not familiar with marine engines, yet. I Kinda get the idea but could you elaborate on diagnosis and repair please. Thnaks

 

[Don S]

Re: noise

The water shutters (Item 6 in drawing) are a flap of SS in the exhaust designed to prevent (slow down) water sloshing up the exhaust when the engine is no running.
When the shutters wear the rubber off, or the rubber gets burned off in an overheat, and the engine is idleing, you can sometimes hear them quickly opening and closing as they bang against the inside of the pipe.

 

[bones774]

Re: noise

Repair or replace? any diagnosis to ascertain for sure?
Thanks

 

[Don S]

Re: noise

Follow the noise to locate, take it apart and inspect. If the rubber is gone, replace the shutters.

 

[bones774]

Re: noise

Did some additionla research and seems like an older 3 piece manifold requires engine removal for shutter replacement. Does anyone know if a 1988 350 Merc is considered an "older" engine with 3 piece pipe?
Thaks

 

[Turn-n-Burn]

Re: noise

from what I gathered.......is this what your exhaust looks like leading from the risers?

if so....just remove the elbow

 

[Don S]

Re: noise

Does anyone know if a 1988 350 Merc is considered an "older" engine with 3 piece pipe?

I used the serial number you have listed in your signature, so the picture I posted earlier is for your engine.