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analyte

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Posts posted by analyte

  2. Confused, leaking NVG149 T/C

    in AWD, Differential, & Transmission Tech

    Posted

    Have you considered transmission issues?? Or I guess I should ask if the trans is original??? There could be pressure building up in the T-Case from a malfunctioning rear shaft seal in the trans and it is pushing fluid into the T-case. I have seen this happen. Also it could be the cheap gaskets that GM uses in there rebuild kits.

     

    Also, I am pretty sure ATF is incorrect to be using in your T-Case especially if it's All-time All-Wheel drive. What you need to be using is that Blue T-Case fluid only found at the dealership. It's pricey but meant for this applications viscosity(again especially if it All-time All-whell drive) requirements and you only need one quart anyway.

     

    Good luck

     

    Nico

     

    P.S. These are just my two cents and I am in no way a reliable source. Just trying to pass on what knowledge I have through experience.

     

    I used a rebuild kit from Monster transmission rather than a GM kit, and the parts appears to be of good quality. I also got some feedback from other sources that the kits were good to use.

     

    That said, I also switched to the Autotrac II based on a dealer recommendation, but my true reason for asking was to switch to the blue fluid to verify the trans wasn't a contributor. I'm comfortable after watching it over the past few days that it's not a trans problem. I called my friend to verify, and he confirmed all the internal bearings and chain was swapped along with the Merchant pump rub kit. The seal didn't look damaged, but changing to the blue fluid made it easier to verify the source.

     

     

    I guess my only course of action left is to swap on a new yoke to see if the that helps even though I don't see a wear pattern or groove. If it still leaks, I'll swap on a new output seal. My last option will be to pull the T/C again and have him pull it apart for inspection. The stains on my driveway are starting to drive me nuts.

     

    Thanks for all the suggestions so far.

     

    Kerry

  3. Confused, leaking NVG149 T/C

    in AWD, Differential, & Transmission Tech

    Posted

    I'm slightly confused and getting somewhat frustrated. I bought my Denali earlier this year, and it was running great with no problems. I was trying to diagnose a vibration/noise after awhile, and the local GMC dealer said it was the T/C and it needed rebuilt. I got the T/C rebuilt by a GM tech friend with all new bearings, seals, and chain. Since that time, I've been trying to figure out why I continue to have a T/C leak.

     

    When I reinstalled the T/C, I filled it with just over two quarts of Mobil 1 ATF. The T/C began leaking after the first drive as I could smell the ATF and the leak was present on the underside. I thought I had just overfilled it, so I checked the level daily for two weeks to see how much it dropped off. it finally stopped leaking when I dropped from around 1600mL to around 1125mL as drained from the T/C. I refilled it again with new M1 ATF, and it again started leaking until around 1125mL give or take.

     

    The yoke doesn't have a groove or wear marks, and the seal continues to look brand new when checked. It only leaks when driven so could pressure be building up in the T/C pushing ATF out?

     

    Any advice on this issue or possible causes? My T/C did not have the weep hole from the pump rub, and I had the kit from Merchant installed to correct. Did this kit change the overall volume to fill the T/C?

     

    Thanks,

    Kerry

  10. I found my issue, but what is this thing??

    in General SS

    Posted

    I have figured out what is making the sound under the hood. This morning the wife and I were backing out of the driveway and it started at 5mph or less. I quickly popped the hood and jumped out.

     

    It stopped, but I had the wife put it in reverse with the brakes on and start turning the wheel like I was backing out. It started again and I was able to pinpoint the origin. It's a black canister with an electrical plug-in on top right beside the brake reservoir with a hose that goes to the back of the intake. It doesn't appear to be part of the Hydroboost system so I'm not sure what it is or what it actually does.

     

    Here is a pic if it will let me attach it.

     

     

    Thanks,

    Kerry

    post-4579-0-81038600-1336845505_thumb.jpg

  11. Odd Drivetrain Noise From Sierra Denali....Any Ideas?

    in AWD, Differential, & Transmission Tech

    Posted

    Ok, I had the T/C gone through with new bearings, chain, merchant pump rub fix, and seals. I got it back in the truck, and it issue is still there.

     

    Again, it only happens under load and stops when I let off the gas. Does it at low speed and when causing, but its not constant and can't be anticipated.

     

    Turning has no effect so I've ruled out wheel bearings. Does a bad front diff howl/growl/whine constantly??

     

    Thanks

    Kerry

  12. Bad Noise Coming From Driveline......

    in AWD, Differential, & Transmission Tech

    Posted · Edited by analyte (see edit history)

    I am looking for help related to this forum thread.

     

    I had open heart surgery in August 2011 for new aortic cow valve and to rebuild ascending aorta aneurysm, so my SSS maintenance fell a little behind (that & work hours).

     

    I noted a new noise coming from the front axle (AWD) in January 2012 with 129,000 miles on the ODO, which has driven me nuts trying to diagnose. I am at 132,500 miles now and it is very prominent now. I have replaced some parts, driven in a car adjacent to the SSS at speed, and was told by Firestone mechanics, that they do not know if it is a bearing or a tire. My tires do not have the best wear pattern, but have another 5000 miles left in them, roll smoothly and track straight.

     

    It is a gear-like growl which begins to be noticeable between 15 to 20 mph and seems to reach full loudness at 45 to 50mph. Shifting into neutral, coasting, accelerating or braking have no effect. Noise is based on wheel speed. Noise is more prevalent in cab than outside when driving a second car parallel to the truck. No noise from rear axle at all, even though there was a gasket leak, which required replacement/refill. Refilled rear diff, front diff, transfer case and trans at 131,000 miles with only mild metal material from front diff. Note I had let front diff go over schedule in 2/2009 at 95,000 miles with notable metal debris on the magnetic drain plug, ... but absolutely no gear noise then,

     

    I replaced all 4 brake rotors/pads with stock AC Delco and left rear brake caliper last month. I replaced front left wheel bearing/hub assembly too, as I was certain that was where the noise was coming from (didn't help). Noted that when I make a gradual left turn (i.e. full lane change within 4 to 5 seconds), that the noise goes away. Noise comes back when going straight or turning right. When I replaced wheel bearing, I noted that CV-joint/inner bearing hub assembly is attached to the wheel bearing with a sliding spline connection and that the wheel bearing is fully supported by the suspension spindle. Therefore, turning left or right should not add or subtract thrust loading to the CV joint, inner bearings or front differential. Based on this I have assumed that the noise should not be originating from the diff thru the CV joint assemblies. I have not replaced the right front wheel bearing, as thermography readings did not reveal any real temperature differences after driving 20 miles home from work. In fact non-contact thermometer readings of the center diff, wheel bearings and CV joint-diff attachment hubs have even consistent temps.

     

    The only other thing worth noting is my 3rd set of tires (Yokahama Parada Spec X) are well worn with the inner edge of both left wheels (directional tires rotated from front to rear only) are more worn (close to bald), which tell me the left wheel alignment has too much camber now. However, the truck tracks straight with no shudder or tire feathering. I have had tires make alot of noise before (i.e. 315mm Yokohama Advan R-compound rain tires on modified Z28, but it just does not seem to be coming from there in this case.

     

    Have you gents or ladies had any issues like this. I have NEVER had any gear growl since I bought the truck new with 400 test drive miles on it in 12/2003.

     

    I have already spent $1100 on brakes and left bearing. If it were a diff, I don't want to run to failure due to higher costs. But if it is just an outer wheel bearing or a worn tire, then I could wait. Trying to stay on a budget for now with past Open Heart Surgery massive costs.

     

    Is the sound constant, or does it have a start and stop numerous times while driving?

  13. Would You Be Scared Of A 1 Owner Ss With 200K Miles On It And All Serv

    in General SS

    Posted

    If you don't have/know a trusted independent then the dealer is the next best thing. I bought my truck out or state so I used the local GMC dealer. If gave me a good chance to see under the vehicle and get estimates, although inflated, so I had a good idea what needed to be done maintenance wise. It cost me $105 for the inspection.

     

    As said before, get the records beforehand. With a VIN, the dealer will print them out for you.

     

    Kerry

  14. Would You Be Scared Of A 1 Owner Ss With 200K Miles On It And All Serv

    in General SS

    Posted

    I just picked up an 06 Sierra Denali with just over 200K on the clock for around the same price. It may be more than some would pay, but it was also a one owner truck that was never wrecked with maint. records. The interior is in better shape than most with half the miles so the previous owner is more important than miles to me. I've done a full service on it, and it drives like a dream. I fully expect to get many more miles out of it, but I still got a pre-purchase inspection from a non-biased party just to be safe.

     

    Kerry

  15. Odd Drivetrain Noise From Sierra Denali....Any Ideas?

    in AWD, Differential, & Transmission Tech

    Posted

    Ok, I've done some searching and I've found the following options for NVG/NP 149 hard parts from Monster among other suppliers. Any preferred resellers for these items?

     

    - Master rebuild Kit

    - Overhaul kit (bearings and seals mainly)

    - Replacement chain

    - Alum. replacement rear case (if hole is found)

    - pump rub fix from Merchant Automotive

     

    What should I get for the rebuild? Should I get the complete master kit or only replace the bearings and seals that are bad? I'll most likely get a chain since I'm over 100K in the truck for my own sanity...

     

    Do the hard part kits come with the new style clip for the pump, or do I have to buy that separately somewhere else?

     

    Thanks again,

    Kerry

  18. Odd Drivetrain Noise From Sierra Denali....Any Ideas?

    in AWD, Differential, & Transmission Tech

    Posted

    Front diff?

     

    Not sure since this is my second vehicle with 4wd/AWD. I don't know how they sound when they fail or start to fail. I just drove it this morning to the store, and it did it twice going and three times coming back over just a few miles. Does a bad diff make this type of on and off sound when the bearing is going out?

     

    does it do it with a/c or defrost off?

     

    I drove the truck without the A/C on and it still had the issue. I know the compressor is free-wheeling, but I don't know if that definitely rules it out or not.

     

    Thanks,

    Kerry

  19. Odd Drivetrain Noise From Sierra Denali....Any Ideas?

    in AWD, Differential, & Transmission Tech

    Posted

    I'm chasing an odd sound that I hope someone can help me with that's more familliar with these trucks. It sounds like a compressor or motor kicking on and off. It only lasts around 3-7 seconds each time it's heard, and it isn't constant going on and off when driving.

     

    It only happens when under load, speeding up and at cruise on the interstate. Therefore, I can't look for it while idling in the driveway. I have tapped the brakes and it doesn't affect or end the sound/vibration. I can feel it slightly through the gas pedal while also hearing it inside at speed. If I let off the gas pedal it seems to go away, but I've yet to be able to confirm it.

     

    I feel confident that it's coming for the engine side and it almost sound like a compressor refilling a tank, though muffled. It doesn't appear to be a PS problem, but I wonder if it could be my A/C compressor coming on and off since it's climate control. It is totally random and doesn't always appear when accelerating or when cruising. Is there anything else on these trucks that would make that sound? Could it be a bearing in the A/c compressor?

     

    Thanks for any help.

     

    Kerry

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