2001 2500HD with 8.1l and Alison. 130k on the OD.
Mostly street driven with rare off pavement miles. It's the daily driver.
Noticed a drop of oil on driveway. uh oh. crawled underneath and could not locate source of any leak, it was blown all over the rear axle. More tracing and located the problem: the dreaded transfer case pump rub. Over time the internal oil pump (retaining clip) in the transfer case saws a hole in the T-case housing. Starts out like a pin hole and expands over time. Now we have troubles. Searched the issue and its more common that I believed. Several companies make a new retention part to eliminate the rub. Was forced to drop T case, crack it open and install the new part, seals, etc. To my horror the oil level was down to less than 1/2 qt. Cleaned up the hole and sealed with JB weld. For details, Google GM pump rub and be prepared for a shock.
Noticed oil weeping from the pto plate on the alison, and all the bolts were loose. easy fix.
Then the steering. Depressing. had a noticeable pull to the right and a hard clunk making left turns. As once before, had to replace tie rod ends, inner and outer. new pitman and idler arm. in doing this, the left ball joint just fell apart. uh oh. Then to make it more fun, determined the left front wheel bearing assembly was shot. Floppy loose and grinding like full of sand. Parts run!
Then off to alignment shop. they discovered the two upper bolts on the passenger side A arm were nearly sheared thru. More uh oh. So another parts store run and now its all done.
In the process noted slight fluid weep from the transmission coolant lines. Those were replaced 2 years ago for leaking and seems the culprit is back. Research shows a common problem. the General needs to step up and make better replacement parts. Might have some cu$tom hoses made up to last longer.
Recently and at random times, the ABS and E Brake idiot lights illuminate. Sheesh. Research says its a faulty ABS module (VERY expen$ive replacement part) or a bad ground. Cleaned up the ground and---no luck. Still randomly comes on. Think i'll just live with that.
Finally, when tank is low and go for a full tank (another expen$ive experience) the fuel gauge goes bonkers, sweeping fully left, right, back and forth like a windshield wiper. Research shows possibly bad ground on sending unit. The ground is accessible without having to drop the tank. Cleaned it up, so next fill up we'll see if that helped.
And to think I was saving up for a Tacoma. Guess i'll be driving the Chevy a little longer than planned. Since all new parts and the truck is paid for, why not. Or sell and list the upgraded parts... At least its good to go for another 100k miles I just do not like the 10 mpg on a good day.
Of all the failures, the puny front steering components seem to fail regularly and the transfer case pump rub is a real concern for any late model GM with 4WD. Benchmark is 100k miles to do the retrofit.
Now, off to work to pay for all this!