Anyone update old generator with new mounts and exhaust?

[twistedtree]

If going to the trouble of installing a separator, I would do it correctly with a below water outlet. You might as well get the full benefit that it offers.


I can't really tell from the videos how much of the outside noise is water and spitting vs exhaust note. It's entirely possible that your existing muffler is correctly sized, in which case it's just a matter of adding the separator, and of course confirming that it won't exceed back pressure allowances.

 

[Steve91T]

If going to the trouble of installing a separator, I would do it correctly with a below water outlet. You might as well get the full benefit that it offers.


I can't really tell from the videos how much of the outside noise is water and spitting vs exhaust note. It's entirely possible that your existing muffler is correctly sized, in which case it's just a matter of adding the separator, and of course confirming that it won't exceed back pressure allowances.

There’s a lot of exhaust noise

 

[Steve91T]

Ordered an Centek 2” inline muffler. We’ll see next weekend what kind of a difference it makes.

 

[AZ2Loop]

I'm looking forward to hearing your results. I have a noisy 4-cylinder Kubota from the mid 90's, and it's bigger than we need. It runs (knock on wood) like a new one, but it is noisy and positioned about 3 feet from the pillows in our master suite.

We only use it for about 1 to 1.5 hours/day when anchored. Such little use that it has not been a priority. Until this thread, I have never even thought of trying to make it quieter, other than contemplating a sound shield. I just accepted it as the nature of the older beast. Now I am rethinking that. Maybe it was more quiet in 1996? Good luck with your project and when time allows, please let us know how it goes. This may be something I should do as well.

 

[Steve91T]

I'm looking forward to hearing your results. I have a noisy 4-cylinder Kubota from the mid 90's, and it's bigger than we need. It runs (knock on wood) like a new one, but it is noisy and positioned about 3 feet from the pillows in our master suite.

We only use it for about 1 to 1.5 hours/day when anchored. Such little use that it has not been a priority. Until this thread, I have never even thought of trying to make it quieter, other than contemplating a sound shield. I just accepted it as the nature of the older beast. Now I am rethinking that. Maybe it was more quiet in 1996? Good luck with your project and when time allows, please let us know how it goes. This may be something I should do as well.

I was expecting everyone to say to just throw it away and get a new one. But this generator, even with 5000 hours, runs great and uses virtually no oil.

I think what I’m going to do is buy a 2” 90 degree mandrel bent SS exhaust pipe. I’ll either mount the muffler vertically straight over the lift muffler or horizontally right before it exits the boat.

I already have the before videos. I’ll make sure to post an after video.

 

[rslifkin]

I'd go with horizontal before the exit. I'm not sure adding an inline muffler vertically after a lift muffler is a good idea.

Also, if you have the option, use fiberglass pipe and elbows, not metal. Even 316L stainless is more corrosion prone than fiberglass when hot, salty water is involved.

 

[Steve91T]

Yeah I know but I’m not spending over $100 for an elbow. I’d rather swap this SS pipe every year or two.

 

[rslifkin]

I'm seeing the 2" 90* fiberglass elbow Centek sells for about $50. Still more expensive than the stainless one, but not terrible.

Personally, I wouldn't trust thin wall 304 stainless in a marine exhaust. If it were thick I'd be ok with it, especially if it were a higher grade stainless, but typical automotive exhaust tubing is pretty thin.

 

[Steve91T]

I'm seeing the 2" 90* fiberglass elbow Centek sells for about $50. Still more expensive than the stainless one, but not terrible.

Personally, I wouldn't trust thin wall 304 stainless in a marine exhaust. If it were thick I'd be ok with it, especially if it were a higher grade stainless, but typical automotive exhaust tubing is pretty thin.

You’re right. I must have looked at something incorrectly as I remember seeing $125 for a 90 degree fiberglass pipe.

Anyway, canceled the pretty SS pipe and ordered the fiberglass one.

I think there’s room to mount the muffler horizontally. I’ll try for that.

Thank you

 

[Keysdisease]

I'd go with horizontal before the exit. I'm not sure adding an inline muffler vertically after a lift muffler is a good idea.

Also, if you have the option, use fiberglass pipe and elbows, not metal. Even 316L stainless is more corrosion prone than fiberglass when hot, salty water is involved.

Good advice. You do not want water in a vertically mounted muffler at shut down to drain back into the lift and overfill it. that could lead to a backflood situation with water at the engine. Also height of any lift is a contributing factor as exhaust gas pushes water uphill.

And when you think about it, diesel exhaust has some serious corrosive gasses mixed together, then mix that with salt water. Add that to some of the inherent problems stainless has with this mix and fiberglass is the best choice.

 

[Steve91T]

Good advice. You do not want water in a vertically mounted muffler at shut down to drain back into the lift and overfill it. that could lead to a backflood situation with water at the engine. Also height of any lift is a contributing factor as exhaust gas pushes water uphill.

And when you think about it, diesel exhaust has some serious corrosive gasses mixed together, then mix that with salt water. Add that to some of the inherent problems stainless has with this mix and fiberglass is the best choice.

Good point. I didn’t think about the amount of water this muffler might have. I’ll try to have it aimed downward towards the through hull if anything.

 

[Steve91T]

Before and after pics. I need to run to the auto parts store and grab more hose clamps so I can double them up. I’m also expecting once the generator runs and warms up the hose, it’ll become more flexible and it’ll level the muffler.

Can’t wait to start it up and see what kind of difference it makes. Gotta wait until my 2 year old wakes you from his nap. If i wake that kid up my wife will kill me.

 

[Steve91T]

Forgot the pics...

Ok what’s the deal with the sideways pictures? Anyone know how to fix that?

 

[Steve91T]

Just ran the generator. Exhaust noise reduced by about 50%! I’ll take it.

Videos will come later when I have time to upload.

 

[rslifkin]

I wonder... Does the inline muffler smooth out the splashing from the water discharge?

 

[twistedtree]

Nice job.


It's so hard to tell from pictures, but that lift muffler sure does look small. Barely larger that a paint can, would be my guess?

 

[Steve91T]

Yeah it’s a small lift muffler.

Adding the inline muffler changed the spraying of the water but I’m not sure it made it quieter.

 

[syjos]

I wonder... Does the inline muffler smooth out the splashing from the water discharge?

Only way to stop the splash noise is with a Gen Sep and underwater water discharge.

 

[rslifkin]

Only way to stop the splash noise is with a Gen Sep and underwater water discharge.

Agreed. I was mostly curious if having more volume after the lift muffler gave more of a steady stream pouring out and less spraying / splashing.

 

[Steve91T]

Agreed. I was mostly curious if having more volume after the lift muffler gave more of a steady stream pouring out and less spraying / splashing.

That’s what I was hoping for.

But. Last month my daughter and I were in the electric dink at sunset chasing dolphins and I couldn’t believe how annoying the exhaust note was. And we were a ways a way. At that distance I couldn’t hear splashing. So maybe this inline will at least help the neighbors at anchor.

 

[syjos]

Agreed. I was mostly curious if having more volume after the lift muffler gave more of a steady stream pouring out and less spraying / splashing.

I'm not sure about the muffler Steve installed, but the Vetus plastic inline muffler is like a maze inside and tend to steady the water stream a bit. I have installed Vetus mufflers on clients generators to quiet them and did notice a small change in the water flow exiting the transom. The amount of change depended on the generator, size of the water lift and the length and diameter of the exhaust hoses. With a large water lift, water collects in the water lift and exits when the water gets high enough and the pressure builds and wooshes the water out.

Back before Gen Seps were widely available, we would install a hose on the generators transom exhaust fitting and slope it down so the water had less height to drop. Only issue was burbling when the hose dipped underwater so adjusting the height above the water was critical.

Side benefit to the exhaust hose extension was reduced soot on the transom by exhausting away from the transom and reducing the "station wagon effect".

 

[Steve91T]

So after dinner I did more work on the boat and decided to fire up the generator again. I forgot this old girl needs some time to quiet down. Might be air in the fuel. Might just need some temperature. Anyway she started up smooth and quiet. From the outside...I couldn’t believe it. It sounded like a dryer vent that was splashing water. The difference was remarkable.

We’re taking the boat about 3 hours north tomorrow morning to anchor for the night. The generator will be running the entire time. I’m looking forward to seeing what kind of difference we notice.

 

[Steve91T]

I am thrilled! The generator is so much quieter! And it hasn’t effected (affected?) performance. We’ve been running it hard with all 3 ac units while underway. Now we are anchored and cooking using a ninja foodi grill (1650 watts) and it’s doing great. We did shut one ac unit down though to be safe.

We notice a difference inside the boat definitely quieter. Outside is a world of difference

Next on the list is an induction muffler. That’s where all the noise is coming from now.

If we can quiet the induction noise then I’ll be done. I’m not going to bother with the water separator. I my opinion it’s not worth the price.

Here are some videos. Hope you can hear the difference


First video is that before. Last 2 are the after.
https://youtu.be/7r4L7YqJfAw

https://youtu.be/61o81AY_gcI

This one was me hanging over the side of the boat at anchor. I wonder if there’s a way to straighten out the water as it exits? Probably not worth it. If someone is bothered by splashing water they are too close.
https://youtu.be/JiNvVBroe3o

 

[twistedtree]

Wow, that is a remarkable difference. Nice job. I guess it's confirmation that the original muffler is way undersized.

 

[syjos]

That is a big difference in noise. Good going!

 

[Steve91T]

Yeah the lift muffler was definitely too small. Maybe it would have been better to just get a larger lift muffler. Either way I’m happy with the results of my inline muffler.

Now I need to deal with the induction noise.

What do you guys recommend?