Loud exhaust Westerbeke 8KW diesel generator

M

Matt

Member
May 6, 2008
97
Braintree, Ma.
Boat Info
400 Db
Engines
Cummins 6cta8.3m 450
I have been trying to diagnose my generator exhaust being noisier than I think it should be on my 400DB. I have replaced the raw water impeller. pulled and cleaned the heat exchanger, cleaned the intake screen and the through hull screen. I still see a almost continuous stream of water out the exhaust port and from time to time I see a larger spurt of water out of the exhaust pot but mostly it's just a steady stream.
The generator has 1100 hours on it I am wondering if it might be the exhaust elbow that needs cleaning or replacing?
Does any one have a video of what the exhaust flow should look like that they could post?

Thanks
 
What type of generator? Westerbeke? Onan?

The water flow pattern you described is normal for the Westerbeke 8.0. A clogged up elbow restricts flow and that probably wouldn't increase the exhaust noise but would reduce the generator's efficiency. If this is a Westerbeke, and I suspect it is in an '01, the elbow is a cheap part (by Westerbeke standards, anyway!) so replacing it on a15 year old boat is probably a good idea.

The 8.0BTD generator engine noise level is normally pretty high. You can quieten it down some by having the valves adjusted to factory specs, but most of the noise is the normal fuel knock inherent in all mechanical diesels so there isn't much you can do about it.

Some owners have tried replacing the factory muffler with a different type, but t he results have been mixed.
 
fwebster said:
What type of generator? Westerbeke? Onan?

The water flow pattern you described is normal for the Westerbeke 8.0. A clogged up elbow restricts flow and that probably wouldn't increase the exhaust noise but would reduce the generator's efficiency. If this is a Westerbeke, and I suspect it is in an '01, the elbow is a cheap part (by Westerbeke standards, anyway!) so replacing it on a15 year old boat is probably a good idea.

The 8.0BTD generator engine noise level is normally pretty high. You can quieten it down some by having the valves adjusted to factory specs, but most of the noise is the normal fuel knock inherent in all mechanical diesels so there isn't much you can do about it.

Some owners have tried replacing the factory muffler with a different type, but t he results have been mixed.
Click to expand...

Okay there is another same year boat at the club and it sounds to me a little quieter. there is another boat with the 7KW gas version and there is almost no exhaust sound from his exhaust just a gush gush gush when his generator is running. my boat is a 01 so maybe I should just replace the elbow. My generator runs fine it stays around 190 degrees and the water out of the exhaust port is barely warm. so maybe I am not really chasing a problem just being over sensitive to the sound.
 
I have an 01 400DB with the same genny, and find it is a tad loud. The water flow out the exhaust is exactly the same on mine with a constant flow.
 
I have a 10BTD and had similar issues. My muffler was a 6" if I remember correctly. I changed that out to a 9" and the difference was remarkable. One of the best things I have done. The therory is that the muffler was too small and basically blew out all the water instead of letting it pool in the bottom of the muffler and quieting the sound. Westerbeke did not recommend adding an additional in line muffler due to back pressure.
 
Frank makes a great point on valve adjustment. Got mine done this winter and it made a significant improvement. Even my wife noticed the difference. I have the same generator.
 
Great things to know about maybe a larger diameter muffler and doing a valve adjustment.

Thanks
 
You could always add a sound box...
 
The last thing you want on an 8.0BTD Westerbeke is a sound box, anyway.

The water pump mounts on the back of the engine well out of sight. It takes a concerted effort (almost mirrors on some boats) to see it to check for leaks. A water pump leak that is undetected drips down the motor onto the motor mount and runs down the mounting rail. If you don't see the leak, you find out about it when the motor mount collapses and the rail is gone. That amounts to about $1300 worth of parts plus the water pump repair ($480) to fix the leak. With a sound box on the generator, there is no way to even look at the back of the engine.

I own one of these things and, while they are nearly bullet proof, they are noisy as hell. Roughly 80% of the noise I get is mechanical clatter from the valves and injectors, not exhaust noise. A sound box would help that, but they are difficult to deal with and can easily lead to over looking the issues mentioned above just because you cannot see or access the back of the engine without removing the sound box.
 
LMBoat said:
I have a 10BTD and had similar issues. My muffler was a 6" if I remember correctly. I changed that out to a 9" and the difference was remarkable. One of the best things I have done. The therory is that the muffler was too small and basically blew out all the water instead of letting it pool in the bottom of the muffler and quieting the sound. Westerbeke did not recommend adding an additional in line muffler due to back pressure.
Click to expand...
A repair person who specializes in generators and house systems told us that Sea Ray did not do us any favors in putting 6" generator mufflers on our boats. He called them undersized and recommended to replace with a larger diameter as you have done.
 
I have a soft side sound box around mine and it seems make a big difference.... When it's time for maintenance you just pull the velcro seams apart....
 
I did consider a hush box but have decided against it. the raw water pump is not a real issue on the 40DB as you can see it and replace the impeller without to much fuss. I just don't think the hard hush box will fit. there is no room really above the generator for a box. I did not look at the soft side ones. I worry that I will miss something if I had a box in place and the extra heat kept in by the box would worry me some. The admiral will just have to put up with the noise if she wants the A/C running!
 
I know you guys have deisel westerbeke and mine is gas. Yours are a little bigger then mine. I have a 3 cylinder 4.5
But the only thing u hear when mine is running is the exhaust water hitting the bay water. Basically you hear nothing feel nothing and most of the big diesel guys that I boat with ask me if I have generator when there standing on my boat on the hook and I say yes it's running. I can't imagine why yours would be so much louder? I have the typical exhaust setup with a lift style muffler.
 
You could try 2 things:

1. Install a larger muffler, like an Onan 14" aqualift unit. I did and it made a huge difference.
2. Install a water separator at your next haul out, if the geometry of your boat will permit it. This will make the largest improvement. Also involves the most work (thru hull, strainer, hoses etc).
 
I also got a soft sided sound enclosure and it works great. Very happy with the result. Removal for water pump and other maintenance takes 30 seconds.
 
LMBoat said:
I also got a soft sided sound enclosure and it works great. Very happy with the result. Removal for water pump and other maintenance takes 30 seconds.
Click to expand...

Where did you get the soft sided enclosure? Who is the manufacturer? I cannot find any when I searched for it.
 
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