I just bought a 1978 Catalina 30 with a Yanmar 11 hp motor. It has a pretty good knock in her and I wasn't sure at what point I should be concerned. Any advise on the knocking? Thanks
Excessive knocking w/Yanmar 11hp
- Thread starter Scope
- Start date
Hi Scope
Most small diesels (and larger ones too) will knock at one stage of their rev range.
Either low, mid range or high revs.
Many will knock at startup, when cold and calm down as they warm up.
So in general we learn to live with it.
A ticking or clicking sound that indicates metal to metal could be something different , like loose tappets.
That sound will be there all through the rev range and get worse as the engine revs climb.
Big end bearing knock (which is pretty apparent in gasoline engines) is a bit more difficult to ascertain because of all of the rattling that goes with a diesel engine.
The basics of running a small diesel is to run it hard and fast.
High speed idle and always run in mid rev range.
In close quarters, I run mine (YSE 12 hp Yanmar) at a speed where I can engage gear reasonably smoothly and do all low speed maneuvering by dropping her into and out of gear. Not by increasing or decreasing the revs.
I would go for a long motor and see how it is after a good two hour warm up.
Ear plugs or wi-fi headphones might fix the problem.
PS never heard of an 11 hp Yanmar.
Gary
Most small diesels (and larger ones too) will knock at one stage of their rev range.
Either low, mid range or high revs.
Many will knock at startup, when cold and calm down as they warm up.
So in general we learn to live with it.
A ticking or clicking sound that indicates metal to metal could be something different , like loose tappets.
That sound will be there all through the rev range and get worse as the engine revs climb.
Big end bearing knock (which is pretty apparent in gasoline engines) is a bit more difficult to ascertain because of all of the rattling that goes with a diesel engine.
The basics of running a small diesel is to run it hard and fast.
High speed idle and always run in mid rev range.
In close quarters, I run mine (YSE 12 hp Yanmar) at a speed where I can engage gear reasonably smoothly and do all low speed maneuvering by dropping her into and out of gear. Not by increasing or decreasing the revs.
I would go for a long motor and see how it is after a good two hour warm up.
Ear plugs or wi-fi headphones might fix the problem.
PS never heard of an 11 hp Yanmar.
Gary
