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rearend metallic whinning at all speeds 2012 silverado


hzhardy

Question

Over the past 6 months my truck has eaten two pinion seals and this week it started making a very loud metalic whine at all speeds. The truck as it sits has 42k on the clock. At this point I wish they would just replace the whole unit since it has been this troublesome. I am reaching out here to ask is there anything I should push for, what should I expect and are the dealers usually set up with proper trainjng to tebuild the driveline (no offence towards the techs I just dont figure the have the tools)

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Any dealer I worked at had some general mechanics, and some specialists. Where I worked I was automatic transmission and general, we had one mechanic that did differentials and manual transmissions. A couple of tune-up specialists, with the rest being general. This was before the elimination of carbs.

 

Any time a seal is replaced due to leaking, it is usually a defective seal, or something external cut or scratched it. When it happens twice, and the second seal shows no signs of incorrect install(like mis-shappen from hammering it home) then it is time to go deeper and find the cause. The only thing running against the pinion seal is the pinion flange. They should have already looked at the surface the first time it was out though. If the flange nut was not torqued correctly the pinion may now be "loose" in the bearings. If that is the case, it will be whiney and will make the seal oval in shape. Good news is, if this is the case, they will be replacing ring and pinion this time.

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The tech they assigned it to is doing exploratory surgery in an engine for a knock and would not be able to get to my truck till late Thursday. What should I expect as a turn around time to replace the gear set? I figure if there are shavings larger than what is normal in the pumpkin it will get new bearing too. Do dealers usually stock specific drive line parts like that? Luckily they put me in a 2015 GMC Z71 crew cab that is ten times nicer than my truck. Thanks for your help and time.

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Given the range of demographics across North America, could not offer any real info on what your dealer happens to carry in inventory. I know my dealer can get parts from GM in anywhere from 12 to 48 hours depending on when order goes in. Anytime I have had to have parts ordered, they would arrive sometime during the night(delivery driver for GM Parts has keys to all parts departments or some secure area at that dealer), and dealer would have parts in technician's hands by first coffee break on a really busy day. That is in the GTA in Canada, no idea if US GM Parts have same or similar system.

 

Anytime you have to pull bearings off of the carrier to re-shim, you would usually change at least the first set removed. It is strange how the loaner vehicle impacts the direct need to have your vehicle back. I am exactly the same way, give me a crappy loaner, I become a crappy customer. Luckily enough for me, due to number of vehicles purchased, when a loaner is required, they go past the in-house car rental, straight out to managers demo rides for my loaner. The one I won't get is the owners 'vette. Can't get in and out of it due to my back anyways.

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I hear about the crappy loaners, I only take my truck to the GMC dealer because their smallest car is the terrain and will not get stuck in a sonic. I hurt and ache to bad to get in small cars. I contemplated using the Cadillac dealer to try and get their loaner, but I don't think that would work out for me lol

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Was able to talk to the tech yesterday about my truck. The pinion bearings were severelly pitted so that tells me the previous tech quite possible over torqued the pinion nut resulting in to much pre load and is probally why I felt a loss of performance.

 

As for the front end he explained to me that the tend to make a noise like that on dry pavement especially as the tires start to wear inconsistantly which makes sense because my right front shows more wear than the left front, but he said he would take it for a spin once he gets the rear assmbled.

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Lastly, my front end started making a light growl on deceleration and turning. The service adviser said it was normal due to having a floor shift and deceleration loads the back of the pinion. I just wanted you opinion on that to see if i should have them look into it.

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If it is normal, why did just start up recently? Where has this normal noise been all this time? By saying it has a floor shift, is he actually saying that if you had bought the SLT model, or the some SLE package that includes the auto 4x4, this noise would not happen? Can't see how the front end really cares where the shifter is mounted. Ask him to unbolt and remove the shifter to show you that the noise won't happen.

 

I would expect to see any noise in the front wheels that changes when steering wheel is turn right to left back to right is caused by wheel bearings. Noise on decel may be resonance from the rear diff that is already noisy. BTW, is the truck in 4 wheel drive when you are getting the noise on decel from the front? If it is in 2wd, there is no load on the front diff regardless of accelerating or decelerating.

 

Not meaning to lump all service writers into a single group, but, getting specific diagnosis such as "decel loads the back of the pinion" sounds a lot more like at sometime in his career he heard this diagnosis, liked the sound of it, and has been waiting for a time to repeat it. Used to be a service writer at the last dealership I worked at that would keep a list of possible diagnosis that he would say when the car was brought in. Luckily, the only person that ever heard that diagnosis was the customer, and on the odd occasion a passing mechanic that would run out to the shop to avoid laughing. Used to bring up some interesting conversations after the real issue was found, and the customer wanted the mechanic to explain it because the service writer would take the baffle with bullshit approach if he did not understand what was happening. Oddly enough, they kept that service adviser around as entertainment. He never actually damaged anything or sold unnecessary service. He was just embarrassing to be around when customer came in. This was in a small rural type city, people are different there.

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I rarely use 4wd and when I have it has been offroad. It had been upwards a year since I had used it, but since I moved to Oklahoma I ended up using it when it snowed. My truck is a ls 4wd so it has the manual shift transfer case. He claimed that since there is a hole in the floor board it allowed more noise to enter the cab and that the noise truning was from the the front being engaged were it is normally not. He essentially scared me off with the diagnotics fee since I am on a fixed income being a veteran student. I think I am going to have them inspect it since it is already in for driveline issues.

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Alot of my issues are my aftermarket 4inch exhaust with the 5.3 drowning out noises, but if I can hear it over it I just feel something is wrong

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