demonte1997 Posted October 10, 2013 Report Share Posted October 10, 2013 I know sounds are difficult to diagnose over the net but was hoping someone can help point me in the right direction here. It is a rhythmic thunking sound that starts around 10mph (when truck shifts into 2nd) and continues all the way up until about 45mph. It goes quicker with speed and I can feel it in the floor/pedal/steering wheel slightly. It only happens when I'm on the gas. As said, it goes away at higher speeds. It also seems to go away if the rpms are high enough (ie: if I put load on the system and the rpms are at 1500, I get more thunking than if the rpms are past 2,000). The sound is similar to what a locomotive sounds like as it winds up and gathers speed. :/ I'm fearing the worst - transfer case or front diff. Some people have said it could be wheel bearings and I have a set of Timkens to put on but I'm pretty doubtful. Others have said it might be missing teeth in the front diff. Even others saying possibly stretched chain in transfer case.. Truck has high miles so I'm sure the driveline is worn.. a lot. I replaced the oil in the diff and it looked fine. Also changed out the fluid in the transfer case... not that it will fix either. 2002 Sierra Denali AWD with 171,000 miles on it. If anyone lives in New England, I'd be happy to drive out to them and let them take this thing for a drive. Quote Link to comment Share on other sites More sharing options...
ccgoodwrench Posted October 10, 2013 Report Share Posted October 10, 2013 Did you check your u-joints Quote Link to comment Share on other sites More sharing options...
shawnss Posted October 11, 2013 Report Share Posted October 11, 2013 Is it in the steering or does it sound like more of a drive train issue? Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted October 11, 2013 Report Share Posted October 11, 2013 My opinion.... If teeth were missing in the front diff you would feel more than what your feeling. You would get the front diff locking up and horrible noises. As for the wheel bearings, dont use the Timkens, get yourself some Moogs. They are built better with better quality bearings. I have seen tons of the timkens fail within the first few months or within a year. I would check for play in the intermediate steering shaft and the bearing that it uses under the dash. Those will clunk around while driving, going over bumps, turning etc. A stretched chain in the T case will cause noise and shuttering though. Its basically one of those things where if you can talk to a GM tech that deals with these repairs, he can tell you right off what and how to look for the issue. Otherwise you will be stuck with everyone saying this and that, and then you having to go spend hours and money on replacing things that might not be broken. If the fluid looked good in the front diff, and you didnt have things falling out of it, its not the cause. I had 142,000 on my 04 and I never had any issues with my driveline. The only thing I ever had to replace was 1 wheel bearing, and a set of inner and outer tie rods. Then again everyones vehicle wears differently. If you have a Harbor Freight near you, you can pick up a what is similar to a bore scope for like $50. It has a camera screen so you can see whats going inside of say the T case etc and that will help you eliminate the big things. Quote Link to comment Share on other sites More sharing options...
demonte1997 Posted October 11, 2013 Author Report Share Posted October 11, 2013 Front and rear u-joints replaced first as I was hoping that was the issue. Nothing changed after so I'm afraid the originals weren't causing the noise. Good to hear that it shouldn't be the front diff. I'm still leaning towards the transfer case. The Harbor Freight bore scope sounds like a great idea. Might be able to see what's going on up there. I'm kinda stuck with the Timkens as I bought them two months ago and don't see any way I'd be able to replace them. Not sure why I had a brain fart and forgot about Moog. I've used their tie rod ends and lower control arms on w-bodies with great success. :/ Is anyone from New England on this board? I'd be curious if someone with a higher mileage truck could give it a listen and lmk what they think. Very much appreciate the info and time from you guys. As always. Quote Link to comment Share on other sites More sharing options...
03AWDSS Posted December 18, 2013 Report Share Posted December 18, 2013 I just went through the same noise issue on my SS last week and it was my front diff, pulled it apart and my carrier bearings are toast. ( i only have 104k But does the sound get louder like with wheelspeed or on acceleration/deceleration ? Quote Link to comment Share on other sites More sharing options...
demonte1997 Posted December 20, 2013 Author Report Share Posted December 20, 2013 (edited) I wouldn't say the sound gets louder. It's the worst at around 20mph if the rpms are low but I'm putting load on the system. As the speed climbs and the rpms are higher, the sound seems to level out and I don't feel the vibration through the floorboard. One thing I will add is that I can hear a little bit of a whining/roaring sound when I let off the gas between 40-50mph. That sounds like the front diff. I got a used low mileage front diff from a reliable source. Thinking about a transfer case too as I'm sure the chain is stretched out just from mileage and possibly other worn internals. Thanks for the replies. Always appreciated. Edited December 20, 2013 by demonte1997 (see edit history) Quote Link to comment Share on other sites More sharing options...
juriha Posted December 20, 2013 Report Share Posted December 20, 2013 I got 2 years and 10k miles on Timken hub assemblies... throw em on. When mine went bad it was more of a clicking noise with random clunks. I'm in VT. Where in NE are you? Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted December 20, 2013 Report Share Posted December 20, 2013 (edited) I wouldn't say the sound gets louder. It's the worst at around 20mph if the rpms are low but I'm putting load on the system. As the speed climbs and the rpms are higher, the sound seems to level out and I don't feel the vibration through the floorboard. One thing I will add is that I can hear a little bit of a whining/roaring sound when I let off the gas between 40-50mph. That sounds like the front diff. I got a used low mileage front diff from a reliable source. Thinking about a transfer case too as I'm sure the chain is stretched out just from mileage and possibly other worn internals. Thanks for the replies. Always appreciated. Sounds like what my truck was doing and it was the front driver Hub assembly. I heard front groaning low speeds and whining at higher speeds. Dont think the worst, I did that and drove myself crazy into hot sweats thinking about the front diff. What you can do but you have to be very careful. Lift the truck up and put it on jackstands, make sure they are stable push on the truck to make sure in several spots. Have a buddy put it in drive and slowly let off the brake pedal. Listen for the noise near the front wheels. Once done gently apply the brakes. make sure you have atleast 3 inches of space between the wheels and the floor. Edited December 20, 2013 by Blown 346 (see edit history) Quote Link to comment Share on other sites More sharing options...
demonte1997 Posted December 24, 2013 Author Report Share Posted December 24, 2013 I got 2 years and 10k miles on Timken hub assemblies... throw em on. When mine went bad it was more of a clicking noise with random clunks. I'm in VT. Where in NE are you? I live in southern CT. I put the Timkens on and there hasn't been any change in sound. One of the original hubs was absolutely gone. You couldn't turn it at all. The darn thing was red from all the heat over the years. Sounds like what my truck was doing and it was the front driver Hub assembly. I heard front groaning low speeds and whining at higher speeds. Dont think the worst, I did that and drove myself crazy into hot sweats thinking about the front diff. What you can do but you have to be very careful. Lift the truck up and put it on jackstands, make sure they are stable push on the truck to make sure in several spots. Have a buddy put it in drive and slowly let off the brake pedal. Listen for the noise near the front wheels. Once done gently apply the brakes. make sure you have atleast 3 inches of space between the wheels and the floor. ^ I threw the Timkens in and it didn't resolve anything. Was hoping for the best. Will report back when I'm able to do more sleuthing. Thanks again for the responses! Quote Link to comment Share on other sites More sharing options...
03AWDSS Posted December 24, 2013 Report Share Posted December 24, 2013 I wouldn't say the sound gets louder. It's the worst at around 20mph if the rpms are low but I'm putting load on the system. As the speed climbs and the rpms are higher, the sound seems to level out and I don't feel the vibration through the floorboard. One thing I will add is that I can hear a little bit of a whining/roaring sound when I let off the gas between 40-50mph. That sounds like the front diff. I got a used low mileage front diff from a reliable source. Thinking about a transfer case too as I'm sure the chain is stretched out just from mileage and possibly other worn internals. Thanks for the replies. Always appreciated. you need to put the truck in the air, so you can spin the drive line and try to pin point the sound, ( bc i just put my front diff back in and now my transfer case is clunking, and its on the output shaft for the front diff... theres a good bit of slack on the drive shaft ) NOT saying that is yours but best to have all 4 wheels off the ground to find it Quote Link to comment Share on other sites More sharing options...
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