Diesel Preignition

[Rgpracer]

Ok, this is kinda a dumb question, but, in my defense, this has been my first diesel and I still find oddities now and again.
My motor sounds like my motor from the 70' that needed more octane. It clatters quite a bit, or, it "sounds" like it anyway.
Does the Cummins require an "octane" booster additive now and again?
I use Hot Shot every other tank full or so.
Would someone please explain what is happening and what I need to do?

Thanks a lot.
Ray

 

[AH64ID]

Diesel fuel is rated in Cetane, not octane.

What hot shot additive are you using?

I haven’t noticed much of a noise change on my 6.7, but I also only do a 3 point Cetane increase for specific reasons. On my 05 a 7 point Cetane boost sounded horrible, so I haven’t done that much of a boost since.

Cetane boost is really only beneficial for low load and low temperature combustion, and cold temperature starting. The rest of the time the motor isn’t programmed for that high of Cetane and it’s not really doing anything beneficial.

Diesels chatter and make combustion noises, but I would try a few tanks without the additive to see if the motor gets quieter.

 

[Brutal_HO]

I'd lose the Hot Shots altogether unless you're using a winter blend and are concerned with gelling.

Here along the Rockies, it just doesn't get cold enough to gel the winter blend fuel.

Even then, the truck has a fuel preheat. I haven't used additives since getting the CP4 recall done, the CP3 doesn't need it and its use to help prevent a glitterbomb CP4 was always debatable.

More than one member has reported regen issues partially attributable to the use of HS EDT, partially fuel source.

 

[RTillery]

A diesel is a self igniting (no sparkplug) system that lights the fuel mixture from the heat of compression. At lower speeds the sound of this is most of the "clatter" that you hear but as speed increases it becomes less noticeable. In a gasser at idle, and at lower RPMs the combustion pressures are lower and quieter.
Preignition in a gasser typically happens at higher RPMs and under higher load conditions. A combustion event typically starts from heat of compression in a hot spot or tight spot in the chamber before the spark plug ignites and there are now, two flame fronts in the combustion chamber. These two flame fronts hit each other and create a shockwave and the noticeable "pinging" or "rattling" you hear. This shock wave impacts the combustion chamber and typically the piston with enough force to start damaging the top of the piston and maybe the valves. It can be seen as minor to major erosion around the head and can completely destroy the piston. Modern engines have "knock sensors" that immediately retard the timing and help reduce the damage occurring.
Diesels are just inherently more noisy. It's just a different cat and you can't make a direct comparison to a gasser. The new electronic controls of the fuel system have quieted them down a lot from the old days. There is still a lot heavier components moving around in a diesel so they just make their own kind of music. Perfectly normal.

 

[Trash Panda]

I'd lose the Hot Shots altogether unless you're using a winter blend and are concerned with gelling.

Here along the Rockies, it just doesn't get cold enough to gel the winter blend fuel.

Even then, the truck has a fuel preheat. I haven't used additives since getting the CP4 recall done, the CP3 doesn't need it and its use to help prevent a glitterbomb CP4 was always debatable.

More than one member has reported regen issues partially attributable to the use of HS EDT, partially fuel source.

I’m honestly surprised to read this about hot shots product. I’ve had nothing but great luck with their winter anti-gel in the winter time here in Cheyenne, and I’ve got multiple co-workers who are more than happy with their EDT/LX4 in the summer. Zero complaints of increased regens.

Learn something new every day.