Making a Yanmar 4jh2 quieter

[carlo de leo]

Hi Folks!

I have this Yanmar 4JH2 and it's too lousy!
The housing is very well insulated, I can do a better job with some timble covers, but overall it's nice.
I heard that some work could be done at the air intake. I had already inspected this and notice there was no air filter inside the housing, but asked my mecanic and he said in this model was not necessary "everything was burned anyway".

Someone with some insight on this please?
Thanks in advance!

[carlo de leo]

In time
....he said in this model the air filtre is not necessary cause "everything is going to be burned anyway"...

[a64pilot]

It’s called intake “honk”if you look under the hood of most modern cars you’ll notice usually tubes connected to the intake that don’t seem to go anywhere or do anything, they are resonators and work to reduce the intake honk.
You can try to see if relocating your intake to another area, like the Lazarette will help, just buy some proper sized hose to see. Put the oil breather hose in a bottle for the short time for your experiment.
You may or may not notice a difference, intake honk is real, just our little Diesels may be so noisy it’s covered up.
I disagree with your mechanic, you need an air filter, there is dust on a boat, often it comes from the wear of the alternator belt, you don’t want to feed that to your engine, it won’t kill it, but I don’t believe it’s good for it either.
I put a K&N filter on mine.

[Tortuga's Lie]

Some of the noise comes from the intake, but you can also help to reduce noise by eliminating the vibrations from the engine which tend to reverberate throughout the boats structure. This is from poor engine alignment and/or bad engine mounts. Engine alignments can be fairly easy but replacing the mounts can be a hassle

[Paul L]

As Tortuga mentioned, if you have original engine mounts then they are ready for replacement.

[01kiwijohn]

You don't need a very sophisticated air cleaner, on a boat, but some modicum of filtration is beneficial. Usually, Yanmar have a filter housing and use a washable foam element as a filtering medium but the purpose of the whole "filter housing" is to reduce intake noise. Depending on how much room you have to work with, you may be able to locate a suitable housing and add a suitably sized non metallic hose to route the actual intake away from the area. If you want to get really scientific, use a manometer to measure any intake restriction so that you don't create other problems. ( I have encountered engine enclosures that were so tight that the air flow was restricted)

[carlo de leo]

Originally Posted by Tortuga's Lie

Some of the noise comes from the intake, but you can also help to reduce noise by eliminating the vibrations from the engine which tend to reverberate throughout the boats structure. This is from poor engine alignment and/or bad engine mounts. Engine alignments can be fairly easy but replacing the mounts can be a hassle

I can be wrong, but it doesn't seen to be the problem. It's noisy also when not undergoing/engaged.

Thanks

[carlo de leo]

Thanks a64Pilot and Paul. I'll try to do some of the adviced.

[Sailmonkey]

Originally Posted by carlo de leo

I can be wrong, but it doesn't seen to be the problem. It's noisy also when not undergoing/engaged.



Thanks

If the mounts are old, even the engine running without being in gear can shake so much that there is transferred noise

[Mariano]

Don't know what engine mounts you have, but try finding the hydraulic ones, instead of the solid ones. You'll note a really big difference in vibraction reduction. The only problem they have is that they don't last as long.

Fare winds

Mariano

[carlo de leo]

Originally Posted by Sailmonkey

If the mounts are old, even the engine running without being in gear can shake so much that there is transferred noise

Well, I have to say the mounts are old (original), but the motor has just 800 hours.

Originally Posted by Mariano

Don't know what engine mounts you have, but try finding the hydraulic ones, instead of the solid ones. You'll note a really big difference in vibraction reduction. The only problem they have is that they don't last as long.

Fare winds

Mariano

I don't know these mounts but I'll see if I found them in Brazil.

[Sailmonkey]

Originally Posted by carlo de leo

Well, I have to say the mounts are old (original), but the motor has just 800 hours.







I don't know these mounts but I'll see if I found them in Brazil.

800 hours or not. There are many elastomers that will degrade with time. Just simply being exposed to air will harden some rubber.

Watch your mounts closely. If the mounts are sagging or allowing metal to metal contact, it time to replace them.

[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.

[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..

[sailorboy1]

[QUOTE=carlo de leo;2630352
The housing is very well insulated, I can do a better job with some timble covers, but overall it's nice.
[/QUOTE]

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.