I've had my '04 LLY for about 2 months now and in the first week that I had it, all was well. I was taking it easy to brake it in real smooth.


I took it out on a dirt road and put it into 4WH and 4WL to test out the xfer case and got back on pavement in 4WH for about a quarter mile at about 45-55 and realized I hadn't dropped back to 2WD so I slowed down and dropped it back into 2WH and took off.


I can't be certain, but I'm pretty sure things didn't sound right - the truck still sounded like it was in 4WH, so I pulled over again, transferred back and forth a few times real slow, tried reverse, and everything I knew to do from owning previous 4WD trucks but couldn't seem to shake the noise.


Now it could just be because the truck is new but it just seems like it sounds like it's in 4WH. The noise I'm hearing (or maybe THINK I'm hearing) is not the turbo whine, or the Diesel "rocks in the dryer" sound - it sounds like gears that are very tightly meshed that are not designed for high RPM that are engaged, kinda like being in 4WH. Then again, when I engage 4WH or 4WL, there is a noticeable change in the traction, RPM, feel of the gearing, and transmission braking, and everything seems to be working fine, so I'm starting to think I'm nuts.


Only problem is, the best I've gotten on this thing is 14.2MPG and I hear all you other guys getting 18MPG out of the gate. My truck is still bone stock. Anyone think something sounds wrong here?


My build date was 2/4/04 - she was born at 9am and off the line by around 6pm - yeah, I'm a bit nuts like that and actually know that stuff. http://www.dieselplace.com/forum/smileys/Approve.gif


BTW: have been doing 70% highway and 30% local miles. HIghway I usually run 65-85 - that probably explains the mileage but the noise still has me a bit worried. Just being overly-cautious with my baby.Edited by: dduffy

dduffy, not having ridden in your truck, it's hard to say. Fuel mileage-wise, 14 definitely sounds low BUT if you are doing a lot 85 mph when on the highway (vs 65-70) that WILL make a big difference.


I would take it to the dealer and ask him to check it out. It could be your axles are low on fluid, possibly additional whine from the tranny which could also be low on fluid, or anything else. At least if you take it to the dealer and even if he doesn't find anything, you've started a paper trail in case you have further problems on down the road.


Good luck.


Steve


PS: How did you get the build date/times? I would love to know that about my truck!Edited by: Raven

Check you fluids.


I'm also intrested in how you know your build times. I would love to know mine.

I haven't gotten 18mpg yet! And i've got 4000 miles on my truck now. The best I've gotten is 16.9 on premieum diesel, and that was babying the truck. The reason for this may due to the fact that the stations here in michigan are still selling winter blend. But right now i'm like you, and have NOT seen 18mpg. Ask the guys that are getting 18mpg where they live. I bet most will be somewhere warm. I noticed your in Cali so i'm not sure why your getting crappy mileage though. Can you here your turbo spooling up when you take off from a stop?

ddufy,


I don't know if it is still possible on the late model trucks, in rare instances the transfer case would uncouple the front from the rear driveshafts correctly when returned to 2WD - however the front differential actuator would remain engaged - usually a mechanical fault, not an electrical one, leaving the front axle carrier & driveshaft rotating (drag & wasting fuel). The front wheels should not be coupled together, but rather able to spin freely, each at their own speed & direction - without the necessity of the front driveshaft rotating, if the actuator has disengaged the front axle correctly. Hope this helps, sort of a dealer issue really - but sometimes they need a little help too.http://dieselplace.com/forum/smileys/Ermm.gif


Todd.

I


The noise I'm hearing (or maybe THINK I'm hearing) is not the turbo whine, or the Diesel "rocks in the dryer" sound - it sounds like gears that are very tightly meshed that are not designed for high RPM that are engaged, kinda like being in 4WH.





The Allison will whine slightly and change pitch while in first gear. This is normal. http://www.dieselplace.com/forum/smileys/Approve.gif

I have about 2300 on mine now and I hear a whine every now and then.


I also don't get 18 miles to the gallon. I would say my freeway/street driving is the same as yours and the best I have ever seen is 16. I usually drive 65-70. My last tank was 14.5 miles to the gallon. I was expecting 18+ miles to the gallon. I haven't been putting #1 in 'cause we don't get it here in very many places-not cold enough.

http://www.dieselplace.com/forum/smileys/Broken Heart.gif I too have not seen the fuel mileage that others have been posting. 15 mpg driving solo in combo local and freeway situations. 11 mph towing 38 ft. horse trailer. Have 1000 miles on new lly gmc dully. Am hoping for improvement when have more miles on odometer. Like the truck and am hoping for better mpg figures.

When ever I go from 4hi or 4lo to 2hi I ALWAYS back up at least 10 feet to make sure the transfer case has disengaged. I know it's a pain, but it cost virtually nothing to do. I use 4wd just about every day and I guess I'm anal about it disengaging before I go onto pavement.


ROB

Try doing the math instead of relying on the DIS. Make sure the tires are properly inflated. Later! Frank

When I first got mine, I thought there was a problem. Mine was just the Allison whine. My sons 2001 2500HD w/8100 gasser/Allison came with a Video Tape about the Allison, and it explained the Allison Whine. My 2003 didn't come with this tape.

PS: How did you get the build date/times? I would love to know that about my truck!


Hi Raven.


Thank you and all the rest of you for your responses! Raven, to answer your question, you'll laugh - I just drove it straight home from the dealer, and before the stickers on the exhaust pipe even had time to burn off, I'd crawled all around under that thing taking pictures of every part of the truck, and every sticker that I could find. Probably spent 2 hours on my back under the truck. The stickers all had the same date and I presumed, that with my delivery taking place a couple of weeks after the date on all the stickers, and the fact that all the stickers had varied within about a 14-hour period, that this was about when each part was installed onto the truck. Couldn't have been the production time on each part since the parts come from all over the place and I doubt that they'd all be built within the same 14-hour period, from different mfgrs. And the boys in Detroit also left some of their internal paperwork stapled to my radiator with all the build codes on it showing the times that the truck apparantly rolled into each station on the assembly line. Was really cool to see how my baby was built.


My dealer (Liberty Chevy, Selma CA) was probably supposed to remove that (as part of the infamous dealer "prep" that they ding you for) and did a great job with leaving the paperwork stapled to the radiator - they also smashed my windshield fluid line when they installed the battery. Obviously they tested the windshield wipers after they installed the juice...NOT. Nice. http://www.dieselplace.com/forum/smileys/Clap.gif


I'm going to check my rear diff fluid just in case they overlooked that too - might explain some of the racket, but like a lot of you say, it may just be the Allison.

Raven, My pickup was used it had 2000 miles on it when I purchased it, I asked the Sales Manager if he could run a profile on my pickup. He got me all the information. It came from GM Vehicle Inquiry Systems - Vehile Build It has the Build Date and all the Option Codes. You might ask your salesman if he could get a copy of that for you, it is nice to know that much more about your truck. You may want to contact Howard M18 here he may be able to get that for you. He has access to a lot of that information, and has been real helpful to most everyone here!!!! Edited by: BIGMoe

U2horse, the HD get better mileage because of the bigger tires, the 1 tons are stuck w/ the real small rubber which makes u run more RPM at cruise speed.


Some 245 or 255 would make an improvement.


More miles will improve the MPG too.

dduffy,


Thanks for the build info! I have little stickers all over. Looks like mine was built on Sat. 1-24-04 at 09:52:54. I'm glad it wasn't built on a Monday or Friday, but it explains why they forgot to install my Pressure Relief Valve, they must have been hung over from Friday nighthttp://www.dieselplace.com/forum/smileys/Angry.gif.