Roperteacher

I have noticed for quite a while now that when my truck is pulling a load and say getting on an on ramp, or getting up to speed on freeway, or heavy cross/head wind, that I get quite a bit of clatter ( Best way to describe it) from the engine compartment. If I let off the Accelerator , it really quiets down. If I am crusing down the highway with cruise on , quiet as a mouse!!! Only under heavy load does it do this. Sometimes more, sometimes less. Different additives don't really make a big difference. WHen I am NOT running an additive it seems to be WAY LESS than when I do run one... Anyone ever experience this?

hivoltage

I have similar noises, sounds almost like "spark knock" in a gasser is the best I can describe it. Mine also comes and goes with throttle changes. I'm not sure if it's injectors but I don't worry much about it any more. The truck runs good and pulls hard so I think the sounds we're hearing are fairly common. I think with the new common rails they are quiet compared to earlier Cummins in turn making it easier to hear all of those little noises.

NickBeek

Yup, it kinda sounds like spark knock in a gasser, and mine has done it since brand new. A buddy of mine just bought a left over '06 and his does it too. I hate to sound like a lazy dealer tech....but as far as I'm concerned it is normal for this engine / drive train.

BTW, I have had valves adjusted and injectors replaced and it has not changed that sound one bit. I now have 61K miles on her.

Bark

Mine will only do it when hauling a heavy load and not watching my tach. If I let it go below 1700 when heavy I get the "spark pre ignition" sound.

Roperteacher

Thanks for the replys guys! Sounds like it is fairly common. Like stated above, my truck pulls great and runs great!

ptgarcia

Monty,

Are you lugging it when it happens? If you downshift does it go away?

jrussell

I think you effectively answered your own question there.

Mine does it sometimes. Seems to occur at around 1800-2000 RPM's the most. It's the loudest when I manually hold it in a gear at that RPM range and gently go on and off the throttle.

Roperteacher

I still agree with the above. THat would explain why when the cruise is on at say 65 MPH at about 1900 RPM is when it's loudest. Head wind really really affects it... Thanks for the help guys. SOunds like it is the nature of the beast!

Spooler

This was exactly why I stopped using additives. The clatter it causes can't be good. Straight fresh diesel for me.

chipmonk

my injector rattle all but went away, after i had 2 bad injectors replaced.

Roperteacher

Well, I had one replaced a month or so ago and they were all tested. Only found one bad one... I think I may have been luggin' the engine just a hair. So I will see! The #5 injector was at 88% the others were all good so I can rule that out..

Spooler

Another thing is where are you getting your fuel. Once had a tank of fuel from Wally World and it ran like crap, injector/timing rattle. Never bought fuel from them again even though they are cheaper.

Roperteacher

Agreed, Wolly world doesn't even sell out here. I usually get mine from the same place and when on the road I like to use Flying J and Loves, etc..

jumper

Mine does it at part throttle before boost really kicks in but while accelerating. More throttle, it stops, less, it stops as well. It'll also do it when loosening the throttle coming out of boost.

I was told by a local diesel performance shop that the stock map has a bunch of timing advance in that region for fuel economy and that's the reason for the noise. Is that true? I have no idea. He wasn't trying to sell me on a solution.

Roperteacher

Thanks for your imput Jumper. Totally sounds feasable!! I can actually hear it FAINTLY when not pulling but I think I am LISTENING for it now! LOLOL