Duramax noise

[thor]

you could also put a deeper trans pan and a differital pan this will double your trans oil and rear end temps will drop by 50 degrees i put both pans on my truck and they will increase the life of both some of the best add ons i have added

[SlickWillie]

quote:Originally posted by Trailer Trash 2

Well I still say it's the waist gate opening on a hard pull with high boost. or the gate isn't closing all the way due to a weak spring.

I don't think the 2004.5 year model up Duramax utilizes a waste gate; rather a variable vane turbo.

[Tom S.]

quote:Originally posted by thor

you could also put a deeper trans pan and a differital pan this will double your trans oil and rear end temps will drop by 50 degrees i put both pans on my truck and they will increase the life of both some of the best add ons i have added

Regarding the transmission, there are some common misconceptions here. Adding a deeper pan will not double the trans oil capacity. Stock, the Allison trans holds something like 8 quarts. No one makes a pan that will hold 8 additional quarts. Also, the only effect it will have on cooling is prolonging the time it will take for the trans to get to operating temps. More oil doesn't equal cooler oil - more cooling surface does. If you want the trans to run cooler, you need to increase the capacity of its cooling system by either adding a larger cooler, or adding an additional cooler. Some folks have added an additional cooler with by-pass valves so they can shut it off during winter driving. As for the rear differential, an aluminum cover can help reduce temps because aluminum transfers heat better than steel and if the pan is finned, it also offers more cooling surface.

[KathyandDave]

Although our problem turns out not to be the problem of the OP, I thought I'd follow through for the benefit of any who are interested. Our transmission would not upshift after some strain, so it made lots of noise and the transmission temp would get high. The quick fix was to pull over and keep the diesel idling until the temp dropped and the upshift would work, then carry on. Later, the GM dealer reported that a "Limp Mode" code had been generated. It turned out that the fuel filter had gotten down to 4% life remaining. Since we swapped it out, shifting has been fine and the temp has been fine, although we haven't really strained the system hard over five hours of towing plus some grocery-getting. How did I let the fuel filter get that bad? Well, it was at 21% a couple of weeks previously. The GM guy said that it drops like a stone from around 20%, or if there's some contaminant.

[SlickWillie]

quote:Originally posted by KathyandDave

Although our problem turns out not to be the problem of the OP, I thought I'd follow through for the benefit of any who are interested. Our transmission would not upshift after some strain, so it made lots of noise and the transmission temp would get high. The quick fix was to pull over and keep the diesel idling until the temp dropped and the upshift would work, then carry on. Later, the GM dealer reported that a "Limp Mode" code had been generated. It turned out that the fuel filter had gotten down to 4% life remaining. Since we swapped it out, shifting has been fine and the temp has been fine, although we haven't really strained the system hard over five hours of towing plus some grocery-getting. How did I let the fuel filter get that bad? Well, it was at 21% a couple of weeks previously. The GM guy said that it drops like a stone from around 20%, or if there's some contaminant.

I'm just curious. Back when GM added the fuel filter minder (seems like 05 or 06) it was my understanding the minder was based on mileage only. Am I incorrect, or have they changed that?

[dsprik]

I also experienced this noise - only once - in my 2002 LB7. 2 years ago pulling through the mountains in TN. Got a little hot and the siren started up. Very disconcerting. I pulled over to let my gauges drop a little. They got near the red line, but not over.

When the engine cooled down a little, there was no more noise. I vote for Trailer Trash's "waste gate sticking" explanation for my screaming under the hood I had that one time. It was definitely not a cooling fan sound that I have ever heard. I have had the diesel that hot again, but the noise has never returned...

*On Edit~ I should also mention that the sound was directly related to engine RPMs - discounting any electric fan.

[sreigle]

My Fords used to get a bit loud, similar to what you GM guys are describing, when towing up long steep grades on hot days and I'm convinced it was the fan. The sound would vary louder and less loud as the fan speed varied. I assume it varied with the temperature. My Dodge also has a fan but I've only heard it once and it was essentially a whisper compared to my Fords. I've never seen the Dodge get over about 210 degrees so maybe that's why it wasn't very loud.

[Tom S.]

quote:Originally posted by dsprik

I also experienced this noise - only once - in my 2002 LB7. 2 years ago pulling through the mountains in TN. Got a little hot and the siren started up. Very disconcerting. I pulled over to let my gauges drop a little. They got near the red line, but not over.

When the engine cooled down a little, there was no more noise. I vote for Trailer Trash's "waste gate sticking" explanation for my screaming under the hood I had that one time. It was definitely not a cooling fan sound that I have ever heard. I have had the diesel that hot again, but the noise has never returned...

*On Edit~ I should also mention that the sound was directly related to engine RPMs - discounting any electric fan.

The fan is not electric. It is mechanical but free wheels at lower temps. And when it kicks on, it ROARS! I would bet money on the noise you and others heard is the fan.

Here's a thread on a GM Diesel website that discusses it - a lot!
http://www.dieselplace.com/forum/sho...ight=fan+noise

[dsprik]

quote:Originally posted by Tom S.

The fan is not electric. It is mechanical but free wheels at lower temps. And when it kicks on, it ROARS! I would bet money on the noise you and others heard is the fan.

Here's a thread on a GM Diesel website that discusses it - a lot!
http://www.dieselplace.com/forum/showthread.php?t=313703&highlight=fan+noise

I don't know, Tom. Still not convinced it was my fan... Maybe. But like you said, a fan "roars". This really was a "scream" - very high pitched. I will check that topic out. haven't been on Dieselplace.com for a bit, but I am a member. Also, I have never heard that sound before or after in the 3 yrs I have been running it.

[SlickWillie]

On the LB7 Duramax, it is unusual to have much fan activity. My son has never heard the fan on his early 04 LB7. However, he knows what the fan sounds like, as he has driven my truck.

[Tom S.]

quote:Originally posted by SlickWillie

On the LB7 Duramax, it is unusual to have much fan activity. My son has never heard the fan on his early 04 LB7. However, he knows what the fan sounds like, as he has driven my truck.

On my LBZ, the fan also runs in the morning after first starting up, but is not nearly as loud, and quits after less than a mile. I have read that this is due to thickening of the fluid in the clutch mechanism when cold and is normal. It may not be as noisy because I don't run hard when cold and the fan may not be engaged as firmly as when lock up occurs from heating. Otherwise, the only time the fan has come on has been in the mountains in hot weather, and there is NO mistaking it has came on! It sounds like it does when cold - only about 10x louder.