At or about 85 mph and 2500 rpm there is a ticking or tapping noise that the engine makes. I can speed up or let off and it goes away.


What is that????

Might be wrong I'm still a bit of a diesel newbie...but at 2500 rpm your pilot injection is on and that makes a helluva lot more noise than under 2500. I'm sure someone with a bit more knowledge will either correct me or append to this


Mark


Edited by: DURAMAXED03

At or about 85 mph and 2500 rpm there is a ticking or tapping noise that the engine makes. I can speed up or let off and it goes away.


What is that????





My '03 did the exact same thing at 85 to 90 mph on level ground. The dealership said there was no problem and did not explain what it was. In another thread, someone mentioned that they thought the ticking, or rattling, sound was the "pilot injection" going one and off. My '04 does the same thing, so I'm pretty sure there is no problem. http://www.dieselplace.com/forum/smileys/Big Smile.gif

Mine does this too, very consistently starting at around 2000-2100 rpm while on the highway going up hills or into a headwind, or while under heavy acceleration. I am also a new diesel owner (about 900 miles on my lly now). This noise is very annoying to me and has me thinking about taking it in to the dealer to have it checked out. It sounds kinda like a gas engine does when it pings or knocks due to cheap gas, or when the timing needs adjusted. I love the sound of my duramax up until 2000 rpm and then this "knocking noise" drives me crazy!


I am not convinced that something isn't wrong with my truck. Does this happen to anyone else at 2000 rpm's? Does this annoying noise go away after the d/a gets more broken in?

WitsEnd,


My truck does exactly the same thing, also drives me crazy. Makes a ticking or tapping noise at about 2000 RPM, but only under moderate load such as going up hill or towing. If I let up on the accelerator the noise goes away, then returns when I get back on the accelerator. It kind of sounds like the noise a loose rocker arm makes (I know it's not a loose rocker arm) just sounds like it. It also is not the pilot injection turning off, I know what that sounds like and it's much different. The truck runs fine, gets good mileage and no fuel in the oil, so I haven't brought it to the dealer yet. If you find out what it is let me know!


Edited by: BVoyles

My truck does exactly the same thing, also drives me crazy. Makes a ticking or tapping noise at about 2000 RPM, but only under moderate load such as going up hill or towing. If I let up on the accelerator the noise goes away, then returns when I get back on the accelerator. It kind of sounds like the noise a loose rocker arm makes (I know it's not a loose rocker arm) just sounds like it. It also is not the pilot injection turning off, I know what that sounds like and it's much different. The truck runs fine, gets good mileage and no fuel in the oil, so I haven't brought it to the dealer yet. If you find out what it is let me know!





Well, I decided to stop by the dealer this morning and requested to have their diesel tech go along for a ride with me. He drove and I rode. He indicates that the 2000 - 2500 clicking noise (which sounds like a loose rocker arm) is indeed the pilot injection turning off. He says my truck is fine. He said the rpm's in which it occurs seems to vary between 2000 - 2500 rpm depending on the truck - he said they all seem to sound a little different. While on the ride, I asked him about secondary fuel filtration and diesel fuel additives. Regarding secondary filtration, he says it is not necessary as long as the fuel filter is changed every 10,000 miles. He also said that diesel fuel additives are not necessary. Given the experts that are on this board who swear by secondary filtration and additives, it kinda makes me wonder about this guy. Anyway, I am now not as worried about my lly blowing up - I will just have to learn to live with the clicking noises above 2000 rpm. http://www.dieselplace.com/forum/smileys/Confused.gif

yes guys, it's the pilot injection turning off. Pilot injection is a small injection just before the full injection. It's what quiets the noise and helps with emissions.

Above 2200 or so, pilot injection is turned off by the computer. That's when you hear the true diesel sound.

You want to know what it would sound like without it, listen to an older Cummins Dodge or a 1997 vintage Ford Powerstroke. They are loud.... all the time.Edited by: hoot