Quieter engine

[HAS]

I noticed some outboard motors have sound absorbing material in the covers
and on the inside of the wrap around cowl assembles, a lot of it is 1/2 inch
foam. The parts book for the 1975 Mercury 850 has a sound absorbing blanket
for the wrap around assemdly on page 6. Would it harm the engine in any way if I put a piece of 1/2 inch foam on the inside of the wrap around cowl on My
1985 50hp. 4cyl. Mercury ? would it make the engine to hot ? would more heat damage the electronics ? it did not have any sound absorbing material when new.
THANKS............HAS

 

[sschefer]

Re: Quieter engine

The airflow to the engine comes from any venting that might be present in the top of the cowling. What you want to use is neoprene like wet suits are made from to get the best sound deadening. Just don't block the vents on top and you'll be fine. There are never any vents on the bottom cowl. Some Mercs had venting on the cowl sides up near the front. I use to cut them in for motors I thought could use the extra air for the carbs. Once you do that, don't bother with trying to kill the noise cuz it aint gonna work.

 

[HAS]

Re: Quieter engine

sschefer
Thank you, I put a piece of foam on the wrap around cowl and it made the engine much quieter, it is only temporary, I`ll
tey to find the neoprene and use that. .............HAS

 

[carholme]

Re: Quieter engine

Be very wary about the use of foam unless it has a sealed surface or you are going to be doing a lot of carb cleaning. As it heats. cools and ages, there will be continuous loss of foam bits which have a tendency to wind up in the carb throats. The one you see in the parts book is completely sealed.

Gerry

 

[xjma]

Re: Quieter engine

You might look into 'dynamat,' which is a sound deadening product people use for car stereo (and other) applications. Peel and stick, and it's really thin so as long as you're not blocking any vents I wouldn't really worry about heat buildup....but not cheap either. You do get what you pay for.

No experience with the stuff in this application but a few pieces stuck to the floor of my jeep (I run mud terrain tires) makes it like a whole new vehicle inside.