Noisy Nissan 9.8 4-stroke

[BobGlover]

I have a 2012 Nissan 9.8 hp that is just out of warranty. Recently it has started sounding considerably louder than my friends 9.8 4-stroke Mercury motors.
It runs a fine as it ever has; starts easily, idles smoothly and doesn't miss at all. Any ideas? Do these motors have mufflers?

 

[pvanv]

No muffler. What sound does it make? They are really very quiet... and are identical to the Mercs.

 

[BobGlover]

You're right; Tohatsu makes'em both. A friend has an old 5 hp two stroke Mercury and my Nissan sounds remarkably like his. I don't think it's my imagination, because a friend who has a newer Mercury said mine sounded loud to him also. I ran the motor every day last week and it runs great.

 

[Sea Rider]

Newer are probably bit less noisy compared to used ones, as long yours performs satisfactorily what the heck!! If steering load is very loose, adjust steering nut to a point as to achieve for boat to travel at a straight water course when tiller is released. Sometimes this simple adjustment will remove or appease unknown sounds.

Happy Boating

 

[pvanv]

Dunno. If the exhaust cover gasket is leaky, you would be loud... but would probably also be spraying water as well. If the oil fill cap were removed, it would be loud, but also would spray oil droplets all over. As Luis suggested, if the bracket/steering bolts are not tight, any vibrational sounds will be amplified.

 

[Sea Rider]

Paul, will a 9.8 (2-4 strokes) prop match the prop of a 18 HP . Was wondering if a 3 x 8.9 x 8.5 will match provided that this prop has same shaft's lenght, spline shape and same number as of the 18 prop. Thanks.

Happy Boating.

 

[BobGlover]

Thanks a lot guys; I'll check the exhaust gasket bolts, the oil cap and the steering bolts. As I said, it runs well as is, and since fall fishing season is just around the corner, it's not coming off the boat unless it breaks!

 

[pvanv]

Paul, will a 9.8 (2-4 strokes) prop match the prop of a 18 HP . Was wondering if a 3 x 8.9 x 8.5 will match provided that this prop has same shaft's lenght, spline shape and same number as of the 18 prop. Thanks.

Happy Boating.

Nope. different splines/shaft.