Making a Yanmar 4jh2 quieter

[carlo de leo]

Originally Posted by a64pilot

Have you had the injectors out to be tested and cleaned?
Varnish on an injector can disrupt the spray pattern and make a Diesel noisier than normal.

No injectors were moved, painted or anything else.

[carlo de leo]

Originally Posted by Perna

IMHO you should have an air filter to decrease engine wear, and maybe prevent catastrophic failure if it tries to ingest debris. It makes no sense not to have one and it will also quieten things down.

Otherwise if you are talking about noise, not vibration, then improving the noise insulation in the engine compartment would help.

best of luck..

Yes, I'll search for an air filter

[carlo de leo]

Originally Posted by sailorboy1

How do you really know this? Is it because it's "pretty"? Have you cut a section to see what is really in there? Is it sound insulation or just heat insulation?

Personally I think builders use the bare minimum engine sound insulation.

It's not a series build boat. Everything in it was carefully chosen by the first owner, and yes it's pretty in deed! I'll try to take a picture next time. But it's not torned, it's firmly glued, with no spaces or voids...