My wife recently asked the question when people were filing in the campground for the weekend "why are most of the diesels so noisy?" The only real answer I could give was because they made it that way because they like it that way. I never really complain because I'm sure I have annoyed many when I was a kid with my jacked up 70 GTO with headers and straight so-called mufflers and now my no so quiet motorcycle. The point of the post is I was totally taken by surprise today. I went to the dump to get rid of some tree branches and this HUGE Caterpillar front end loader came in next to me to move the brush pile and you could barely hear it. Do you think the big "quiet" truck will catch on? Nah, big boys like noisy toys.

The newest diesels are nearly as quiet as their gas counterparts and are more quiet than big block gas engines of yesterday. It's hard to hear them until they're right next to you.

Diesels really don't have to be noisy. Little boys like their toys.

Diesels are noisy by nature, you wanna hear a Deutz air cooled on cold start up. The manufacturers have gone to great lengths to quiet them down, I am really impressed with our 05 Cummins, but there is a certain element that feels the need for straight pipes and megaphone tips.

You can't hear the new ones, especially in the cab :B

The difference between the noisy ones and the quiet ones is in the injection system. Old diesels, like the 2002 and older 5.9L Cummins for example, do one injection event per combustion cycle. Newer common rail fuel injection technology (2003+ Cummins 5.9L) allows for multiple injection events per cycle, thereby spreading the explosive power over a longer time and quieting the noise of combustion.

Diesel noise | Good Sam Community

Bonefish
Explorer
Jun 01, 2013
N-Trouble wrote:
The sound you hear from your 7.3 is not the result of detonation rather noisy injectors. Most cetane boosters contain additives which lubricate injectors making them quieter. THe injectors on the older diesels are what produce most of the noise you hear, not the engine itself.

The product I use does have injector lubricant and cleaner. It was suggested by a Ford diesel mechanic and helps older diesel with the low sulfur fuel.
camperforlife
Explorer
Jun 01, 2013
I certainly appreciate the comments. My experience with diesels is limited to tractors back when I was at home on the farm many years ago. We did have one of the very early Chevy diesel pickups that seemed to be a mechanical nightmare. Pop loved to hate it. When I started this topic I wasn't sure how it would go but am happy to read many great respectful posts. When we retire in 5 years or so and plan on spending much more time on the road, a new diesel might be in my future.
mosseater
Explorer II
Jun 01, 2013
Really amazing the leaps in technology of the diesel engine. I work for Mack trucks (Volvo)and if you want to hear where most of the noise comes from, it's the high pressure pump and the nozzles. The sound of the injection pump being tested alone makes you run for the hearing protectors, and the piercing chirp of nozzles popping at 5000 psi makes my skin crawl, I can only imagine what higher pressures sound like. The two together at high speed are almost unbearable to listen to even without combustion in the picture. It's remarkable that they can quiet them down to the level they have.
4x4ord
Explorer III
May 31, 2013
phenrichs wrote:
To summarize all that has been mentioned....

There are 2 and ONLY 2 factors in the noise level of a diesel.
1 = age, older ones are noisier regardless of maintenance history. The new ones will get louder with age as well. I am referring to the engine noise only.

2 = the owner, some just like them louder, some deal with the noise as a trade-off for more performance.

Are you thinking that the only difference between a 1998 Dodge and a 2011 Ford is age? That the 2011 Ford will sound like a '98 Dodge once it gets 15 years old?
chrizg
Explorer
May 31, 2013
Guilty here, and over the top. Mine came with a 5" pipe from the turbo when I bought mine, so it is pretty loud but I like that I can move more air through the system.
Slated4Greatnes
Explorer
May 31, 2013
Bonefish wrote:
I am one of the guilty ones with a 7.3 noisy diesel and have no plans on trading it in. :B

One thing I have noticed that the noise level of my 7.3 dropped slightly when I started using the cetane booster. It appears to make the fuel burn more effeciently and eliminate the detonation rattle in the older engine.

If you want to reduce the noise in a 7.3 add a regulated return.
phenrichs
Explorer
May 31, 2013
I should add that I am guilty here too. I have an 06 Dodge and it is a bit louder than I care for because I replaced the exhaust with aftermarket because it was half the price. I would prefer quieter but in the interest of noise reduction it does keep me on the modest side when pressing the go pedal.
N-Trouble
Explorer
May 31, 2013
The sound you hear from your 7.3 is not the result of detonation rather noisy injectors. Most cetane boosters contain additives which lubricate injectors making them quieter. THe injectors on the older diesels are what produce most of the noise you hear, not the engine itself.
Bonefish
Explorer
May 31, 2013
I am one of the guilty ones with a 7.3 noisy diesel and have no plans on trading it in. :B

One thing I have noticed that the noise level of my 7.3 dropped slightly when I started using the cetane booster. It appears to make the fuel burn more effeciently and eliminate the detonation rattle in the older engine.
N-Trouble
Explorer
May 31, 2013
esfd243 wrote:
I am almost disappointed in the quietness of my 2012 D/A. I drove truck for 10 years and love the sound of a hard working diesel. Although the truck is as sweet as is comes, I love a good rumble and some black smoke now and then. I guess being as green as I can does have some disadvantages.

Have the same truck and to think if you want to make it louder means you have to drop over a grand and break the law doing so... WIth all the emissions******(DPF/SCR/DEF) you cant just go hacking at the exhaust without having a tuner to delete the emissions or you'll start throwing codes and go into limp mode. The days of making your truck louder by simply swapping out exhaust are long gone...

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