I have an 07 Classic 1500 Z71 that has developed a rer end howl. Dealer replaced rear end some time ago, last year I believed and has been fine till a couple weeks ago. I put the truck up on the rack this weekend and verified it was coming from the rear end. Everything feels tight and there are no visible leaks. Of note I did add nearly 1 qt of rear end lube last week to top it off and the noise did not change. Not sure if dealer did not put enough in or if it is dissapperaing somewhere else. Any ideas on what is wrong? Any additives that could be added to quieten it down?

 

If you had to add a quart to it, ouch. I'd pull the cover off, drain it, and look at the gear wear.

 

Yep,

She's burnt up being that low on oil (howl confirms it). You'll probably find a leaky axle seal.

Allan

 

Called the dealership yesterday. Service Mgr said was likely a bearing. Said that being a quart low wouldn't hurt it! I'm dropping it off there tomorrow and will let him tear into it and tell me what he thinks. I told him I thought that they had either not put enough oil in it when they rebuilt it or had set it up wrong and the gears had worn wrong causing the howl.

Allan, I can't find a leak anywhere on the rearend. I know this doesnt mean that there isnt one but there is nothing apparent.

 

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If you have additional questions or concerns, please feel free to contact me privately.

Louis
GM Customer Service

 

I don't think that diff holds quite 2 qts. So, if it where 1 qt. low thats 50% low. I hope it is a bearing as that would be the cheaper fix.