What's the proper sound of a diesel?

[Seasoned Carpentry]

I have a Jinma 354 with 200 hours that runs fine. I had a fight with some branches in the woods and the muffler lost, so I put on a modified exhaust system using a stock tractor muffler from the local auto parts store. Had some leftover parts from when the exhaust was routed under the tractor. Hated that so changed it to straight up. I connected an offset angle to the straight up elbow off the exhaust manifold. Muffler slides over the offset at about a 30 degree angle to the rear and I routed exhaust pipe using another elbow straight along the ROPS to the rear. Love it. Keeps the exhaust out of my face and the tractor purrs like a sports car.

However it put the exhaust noise to the rear allowing me to hear engine sounds more clearly. I hear what I feel is a definite knock, somewhat metalic sounding, from the engine. This being the first diesel engine I've owned I wonder how much knock is normal for a Jinma diesel. This baby has run fine for two hundred hours, so I tend to assume it's normal and that I'm hearing it more clearly now that the exhaust has a more tuned sound than the original muffler and is separated by distance from the engine sound. Any comments would be appreciated.

 

[Bird]

Of course, I don't think anyone can say for sure without actually hearing it, but I'll bet it's a normal diesel "knock". When you're accustomed to gasoline engines, diesels, especially when idling and cold, sound like the pistons, rods, and crankshaft are about to go separate ways.

 

[JohnS]

I agree with Bird. When I got my first Jinma, worried about the same thing. If it was my car, I'd be in a panic. The chinese diesels, especially the non-epa approved engines, tend to have a little higher compression than many other diesels. Makes for slightly more knocking.

 

[DieselPower]

Unlike most gas engines that all sound the same diesels greatly vary by engine design. Some are rather quiet while others can be heard in the next state. It's just a diesel thing. Most mechanical fuel system diesel engines have a very noticeable "knock" to them.

 

[California]

What's the proper sound of a diesel?

There's probably a lot of variety between different models - but 'proper' seems to include a sound like a few guys banging on a manhole cover with sledges. When I bought mine I tried stuffing a rag in the exhaust to distinguish exhaust noise from the rest of the racket, exploring to see if a new muffler might quiet it down. But that muffled a single slight baritone note and the clanging racket continued unchanged. Just the nature of the design, apparently.

There's a sound file at the bottom of my sig photos. I compressed it for faster download which took some of the sharpness out of the sound I recorded - it was even harsher in the original version.

 

[3RRL]

Sounds to me like you are describing the normal racket from a diesel. Have you adjusted the valve lash on the Jinma yet? If not, that might make a difference? But it will never sound like a car though.

 

[johnk]

Sounds like a 50 caliber machine gun profiling. Nothing wrong with that sound.. No smoke, good power, don't worry...

 

[quicksandfarmer]

Seasoned Carpentry -- Can you post a picture of your muffler routing? I have a 354 too, and it only took me about 15 hours to have a run-in with a tree like yours. I had it welded back, but I'm trying to get a more protected routing.

Thanks.