I know what you're saying but this knock we're all talking about really sounds foriegn to the sound of a Cummins. It's not a "normal" knock and to me it just sounds wrong.

 

While knocking noises in a diesel are common, a knock that seems to come from one or two cylinders and not the rest is not normal.

 

Hello All,
I am new to this forum and diesels for that matter, but I do love my 2004.5 600 Q/C 4x4 shortie. However, I think that I may have the infamous injector knock. I am getting about 13mpg city/ 18mpg highway, so I have no complaints about mileage and power seems to be awesome as well. But... I do notice a slight knocking noise when I go from neutral to drive at idle and also at 1500 to 1600 rpm during acceleration. I am located in Sacramento and would like to know if anyone can recommend a good dealer to take my truck to for service. All input is appreciated. Thanks in advance!

 

SAC600 .that sounds pretty normal and with those mileage numbers I think you are ok . I drive concrete trucks with Cummins and man you ought to hear those L-10 and M-11's ........Cummins are clattery engines but outlast them all !! Thank god these don't have that metallic ring of the big engines ...flame meeting the metal I was told causes the ring .

 

Would anyone say it's safe to say that this "knocking" sound is definitely one or more bad injectors? Does anyone have a story about getting injectors replaced and the sound going away? I am trying to whether to take the truck to the dealer or not.

 

Mixer Man,
Thanks for the reply. I think that it sounds "normal" also, but I am paranoid due to all of these posts about bad injectors. I appreciate all input, especially from experienced diesel owners/drivers like yourself.

 

I had all 6 injectors replaced at 2,000 miles for engine miss . The pinging sound was reduced by half , but its coming back again at 9,000 miles ( but no miss ) .

 

So I guess it's possible there's no connection between "bad" injectors and the pinging sound.

 

I put some Diesel Additive when I filled up and it made a difference in the knocking. Says it lubes and quiets the pump, seems to do just what it says.

 

Sorry I haven't responded earlier but have been offline since Hurricane Frances. I have run 5 tanks of fuel thru my truck since having #5 injector replaced and every tank I have consistantly inproved by 1 MPG. I know average 16.5 MPG, I also think I have one more injector that needs replacing but it only knock once in a while. The truck still sounds much better, you know like a Diesel should and not like its about to through a rod. I have also decided NOT to use ANY ADDITIVE.

 

Ok, how would a new diesel owner know what is considered severe knocking? Even for a first gen owner moving up (?) to a 600, the sound is completely different. When I shift into drive at idle, I hear a disticnt, rather loud, sound that sounds like tink-tink-tink-tink. Is this what everyone is calling injector knock? My dealer says it sounds like every other diesel, but I don't hear it coming from 3rd gen 555's my friends own. How do I know if I have a real problem or not? My mpg seems a little low, but pretty much in line with what I am hearing.

 

Well, on mine the knock occured between 800 and 1100 RPM's and made a very distinctive knock like a rod knocking. Normal diesel noise is more like a lite knocking and lots of valve like clattering. At least to me it seems this way.

 

Yes, Yes! That's just what mine does. With my truck, if you're driving slow, about 850 rpm in 3rd gear, the sound goes on and off. It's about 1 second making the sound then 1 second not and this cycle repeats...

 

I got the loud knocking at 7,000 miles. Was most pronounced at idle and in gear. Decided to try Hammerdown #1500 diesel fuel conditioner. After 3 days, the knocking disappeared. I just passed 10,000 miles and still very quiet. Just like the day I drove it off the lot.

 

I also had a mild engine knock. I took it to the dealer and they changed out the timing gears and the lifter rack, seems to be alot better. I too have the 70 mph vibe and have to wait for a fix. HERES A TIP, if you have many problems push for a full bumper to bumper 100K warranty, they just might give in.