Wondering about exhaust maintenance on 330 DA

Capt.Will

Capt.Will

Active Member
Aug 15, 2016
148
Lake St. Clair
Boat Info
1997 Sea Ray 330 Sundancer
Engines
7.4 MPI Mercruiser Inboards
Vessel: 1997 Sea Ray Sundancer 330
Engines: 1997 7.4L Mercury Bluewater MPI

Issue: Occasionally in choppy water and when I have the tabs slightly down to take off to plane the boat I hear a grumbling sound which sounds like louder exhaust noise than normal. It's not all the time this happens but when it does it seems to be on the STD side of the boat. Could be wrong about which side, but generally speaking it's just louder.

Question: Are there parts or flaps in this exhaust system that wear or need replacement or maintenance in the life of the system? I ask because I have no idea what's inside the system because I have never seen it off the boat.

Thanks for any insight to this matter.
 
Capt.Will said:
Vessel: 1997 Sea Ray Sundancer 330
Engines: 1997 7.4L Mercury Bluewater MPI

Issue: Occasionally in choppy water and when I have the tabs slightly down to take off to plane the boat I hear a grumbling sound which sounds like louder exhaust noise than normal. It's not all the time this happens but when it does it seems to be on the STD side of the boat. Could be wrong about which side, but generally speaking it's just louder.

Question: Are there parts or flaps in this exhaust system that wear or need replacement or maintenance in the life of the system? I ask because I have no idea what's inside the system because I have never seen it off the boat.

Thanks for any insight to this matter.
Click to expand...
No, not to my knowledge. Is the through-hull exhaust dropping down into the water by chance, and you're hearing that noise? Choppy water and the stern dropping down as you get up on plane suggest it could be that. You don't say this is something you've always heard, or if it's recent.

Can you determine if the sound is coming from the engine compartment or where the exhaust exits the hull?

My 3780 Regal had twin 7.4's. Both of them had some sort of mechanism inside the exhaust hose that was delivered supposed to keep water from backfilling in, like the blades you see on an airplane engine. My 330DA Sea Ray didn't have that though.
 
Does anyone know who the manufacture of the exhaust system is on this vessel? Thinking I could see if there are some other break downs of the internals of the system.
 
i had a '95 330DA for 9 yrs. I had something similar. Our best guess on this noise is coming from the strb exhaust bullet. Depending on weight, trim, seas, etc, it would appear that the exhaust bullet would develop a "vorticies" that allowed an open air path for the exhaust and it got louder. There were no issues, other than extra noise at times. Never did figure out the exact reasons.

For my boat, there were no moving parts to fail in the exhaust, but you might check the insides for any delamination of the hoses or fiberglass parts.

just my .02
 
I think the manufacturer is going to be Sea Ray. My Merc manual only goes so far as the manifold. I think everything else is up to the boat MFG but I could be wrong.

Both my 340 and now my 400 did/do what you're describing on occasion. Sea state, wind direction, how much fuel I'm carrying all seem to impact when/how I'll hear the change in exhaust note. IIRC I think it's more prominent for me in a following sea...I think.

I don't think anything's wrong with your boat. But it certainly wouldn't hurt to inspect all the bits and pieces of the exhaust...

1697644492334.png
 
Ohh and in the "for what it's worth" category, removing those exhaust tubes is not fun. Unless there is a trick I don't know about, it's a lot of brute force and patience to get those buggers to let go...
 
Capt.Will said:
Vessel: 1997 Sea Ray Sundancer 330
Engines: 1997 7.4L Mercury Bluewater MPI

Issue: Occasionally in choppy water and when I have the tabs slightly down to take off to plane the boat I hear a grumbling sound which sounds like louder exhaust noise than normal. It's not all the time this happens but when it does it seems to be on the STD side of the boat. Could be wrong about which side, but generally speaking it's just louder.

Question: Are there parts or flaps in this exhaust system that wear or need replacement or maintenance in the life of the system? I ask because I have no idea what's inside the system because I have never seen it off the boat.

Thanks for any insight to this matter.
Click to expand...
You probably will want to inspect the exhaust hoses and manifolds for damage but it’s possible that it’s a more simple issue. Make sure your impellers are pumping enough water. If they are not then the mufflers will not fill properly and that may be the issue.

Another possibility: I have at times had the exhaust start to sound louder while running in weedy areas. I believe that weeds are building up on the front of the bronze outlets and creating an air pocket of sorts that creates noise. To clear it I come off plane and let the boat stop. Then put it in reverse for a few seconds. That seems to clear the weeds and all is well again.
 
What Creekwood said... I have notice in chop or "weeds" that the exhaust note or sound would change, almost sounds like the exhaust is no longer exiting through the bottom of the boat (more like a normal through hull exhaust). I always assumed it was an air-pocket or some other anomaly that allowed the exhaust to travel from underwater exhaust to the transom maybe in a pocket or path of air for lack of a better description. I could usually get the sound to go back to "normal" buy turning the boat back and forth.
 
Sorry I was thinking you were referencing the thru hull exhaust, not the underwater exhaust.
 
I did find the manufacture tab on the mufflers. The maker is Centek Industries.
 
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