While poking around my truck trying to figure out what is going to fall off next. I found something odd (well that I don't know of)

Anyway, I was looking at fuel lines, the one that supplies the CP3, the return fuel line on the CP3, and then the High Pressure to the fuel log. Well then off of the log are the 6 injecter lines, and the one return off of the pressure relief valve. Ok, now I look again, there's a fuel line, and banjo that runs to the back of the cylinder head. No it's not the number 6 incjecter line, it runs to the back of the cylinder. Almost like it's a fuel return from the injecter lines? Is this what keeps fuel circulating? I know the CP3 will pump back to the tank, but what the heck is this line for?? I will try and take a picture, it's really hard, but if you have a newer gen truck, check it out, any help would be appreciated.

 

Is it the heated fuel return?

 

Low pressure injector excess return. The banjo on the back of the head actually isn't a banjo but a one way check valve. If you ever pull the lines for any reason don't get them mixed up.

 

Interesting. Are the pre and post injections lower pressure?? I wasn't sure if it was like a pressure valve too or what? I would think that any pressure the injecters see is high. Hmm, that's unique.

Still hunting down this nose. I really think a front acc. pully bearing is about to bite the dust. Gonna check a few more this weekend.

 

i think i have the same noise, it happens more when you have the windshield defrost on, and the AC pump kicks in. thats where i get it the most, or when i first start up the truck, and it heat cycles for a while, seems when the alt is loaded up, or the belt it self is loaded up, it make the noise, never while driving though, until i stop at a light or some thing , then i hear it again. let em know if you find it, because i am still looking, been months now.
i will be changing the water pump and bely soon, and will be checking all pulleys and bearing in the idler and tensioner, i will let you know what i find then.

 

Does this noise sound kinda hollow. Like in a coffee can. Bend down and put your ear right in front center of the radiator. See if you can hear it really good there. If so, then it's either your belt tensioner or water pump.

 

sorry to get off topic, but it sounds more like a vib that you can hear, but does really vib at all. i have been under the hood while running, cold and hot, putting my ear everywhere with out getting sucked into the fan blades. i have a small crack in one of the fan blades , and i though it was making the noise, but it isn't that. only loaded does it do it, ac pump running, heating gride on cold start up, etc. seems to me it is some thing related to a pulley, bad bearing, tensioner, cracked alt mount, water pump, which is either leaking, or have a bad gasket, only leaks when cold, and only some times.gets warm, and it doesn't leak. had a hell of a time finding that one, just so happened to add washer fluid at start up one day, and had a peak to see anything, and there it was, leaking.

 

Jammer, sounds very close, I do hear it when cold, in fact yesterday, head in front of radiator, and it sounds "Squilishy" however once warm it's gone. It's only while driving that I hear the really odd noise, I have no idea what the heck it is. Other than that it's a great truck, but man do I worry about it breaking down more than others. Gonna go out and check the pully, will let you know what I find.

 

I have a similar noise sometimes when cold.It sounds like someone blowing into a pop bottle lasts a little till truck warms up and then goes away.Mentioned it to dealer so it is recorded.He mentioned to shift truck int o neutral to elimanate the tranny as the sound goes lower and higher with rpm's.Lately it is not doing it seems to happen in below 0 conditions one of those ghost in the machine noises