I had my 2008 suburban at the dealership for lube, rear u-joint replacement in mid-March (80,000 miles). Mid-May, after a 1,000 run to my vacation destination, the transfer case locked up while backing into a parking space. Bottom line, another dealer diagnosed problem as loss of fluid in transfer case. Drain plug was only in 1 1/2 threads. Neither dealer has ever heard of them coming loose. Mechanic provided some nice pictures. I don't suspect foul play. Any ideas?

 

i wouldn't imagine it just came loose on its own, maybe someone mistakenly loosened it and forgot to tighten. I've heard of some wacky stories of people draining tcases when they pull the driveshaft, hard to say without being there when it happened

 

If no one touched it since the mid march service/lube, then you know what happened. The first dealership didn't tighten it all the way and it slowly loosened. Things happen and everyone makes mistakes. Getting them to admit it is something else.

 

I think, the mechanic might have forgotten to look at the drain plug while taking picture. Remove the oil and also metal shavings present inside the oil. Fill new oil and then check the transfer case again.

 

BMB: Welcome to the forum.

Even if it was only screwed in 1.5 threads, I doubt it would drain the Xfer case. If it did, the undercarriage would be coated w/ the lube. More likely scenario if it truly was empty is the original dealer drained it and didn't refill.

Did the mechanic check to see if it had been cross-threaded? That would explain why it was only in 1.5 threads.