We had a Tohatsu 8hp four stroke from 2012 that had a whine from new. It occurs at
RPM a bit over tickover, under light loads; for instance when reducing speed.
I complained under warranty, and was told it is intake induction noise. I was given a
propeller with a bigger pitch. This reduced it.
Since 2014 we have a 9.8 four stroke which is basically the same design. It has exactly the same problem: under light loads when reducing speed.
I stopped worrying about it.
We now use the
engine since more than 9 years and have had the following issues besides the whine:
- Spark plugs fail suddenly. Good to take a spare
plug and tool for longer distances
- The prop
shaft seal started to leak, replaced
- The
engine suspension rubbers failed, replaced
- Some
corrosion issues; not too bad since when I bought it I took almost all bolts out and re-installed them with grease; and used Waxoyl especially under the engine cover.