gary arnold Posted August 27, 2020 Report Share Posted August 27, 2020 bought this truck brand new. at 65k, after years of towing an airstream trailer i started getting the dreaded howling in the drive train. noise was coming from the front diff and rear pinion, i rolled with it till at 100k , i spun out on black ice going 15mph..clipped the curb..bent a axle!. so rebuilt the rear, axles, berings, carrier& pinion berings, seals...2 days in the driveway all good. fyi - i know their is yes and no's on using a posi additive,but used it anyway.. the shitty ratchet design posi seems to really like it. well flushed the transfer case & front diff and did fresh fuilds. the rear was spinning like a swiss watch. the noise lessened but now was consentrated to just the front, making progress. ive been looking foward to doing the front diff next till today. hit the gas leaving a traffic light and BANG..sounded like when you drop a driveshaft on a holeshot. wow.. no drive..no reverse..no park..just a bad howling gearing noise even in neutral!. did the transfer case chain snap ?? did the tranny crap ?? any cues....Bueller ? Quote Link to comment Share on other sites More sharing options...
someotherguy Posted August 27, 2020 Report Share Posted August 27, 2020 There's no "yes's and no's" on the posi additive, you do not use it, period, in the Eaton Gov-Loc which is what the G80 option on our trucks is. It's not a posi, and there's a TSB from GM about why to not use posi additive but in a nutshell it can cause it to not work correctly. Beyond that, I don't know much about AWD's as I have not much experience with them on these trucks, both ours are RWD 06 models. However, from reading others' posts over the years, not having park could easily be a blown front diff, though I guess also the transfer case being bad could be possible. Normally at 100K I'd say the transmission is highly suspect but when these transmissions go you'll lose gears but not park. Richard Quote Link to comment Share on other sites More sharing options...
gary arnold Posted August 27, 2020 Author Report Share Posted August 27, 2020 thanks richard. ill look for the gm TSB. could the output tranny shaft blow out ? not a drop of fuild leaked. if the front dif blew, id think the rear would still drive..the truck just rolls. maybe the transfer case input shaft snapped clean off? kinda sounded like the chain was whipping in the case. guess ill pull the case 1st. Quote Link to comment Share on other sites More sharing options...
IndySilveradoSS Posted November 18, 2020 Report Share Posted November 18, 2020 updates? Quote Link to comment Share on other sites More sharing options...
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