Home Forums Gear Hunting Trucks and Four-Wheel Drives GM Transfer Case

Anyone here experienced a dreaded “pump rub” issue with their late 90’s early 2000’s GM pickups. I noticed mine making a noise underneath this fall. It’s now got a hole in the top of it and is leaking. Anyone replaced one themselves? Or can recommend a good place to buy a new remanufactured one?

Good ol NP 246. Yes, I've done them before. Pretty easy job. Did the T-case on my wifes 99 suburban and my 2004 GMC 1500... You'll need a gasket that goes in between the t-case and tranny and new t- case fluid. The kit to fix the problem is not too expensive and is a good preventative measure that every gm owner should do, before your case develops a hole... Good luck with yours..

I did the rub kit In my Duramax last weekend.

The Merchant Automotive kit comes with the gasket, but if your case already has a hole rubbed in it, you will need a rear case half also. IIRC, Rock Auto has 'em

My 2003 started leaking at ~108K. Side of the case looked damp. I ran my finger over the area, and a spec of magnesium broke free and the fluid started to run out of the pin hole.

I patched my case, and took it to a good shop for the inspection and case saver. No more problems, 40K miles later.

When I was looking to do it myself, there were replacement cases available made of aluminum which is what was used in later units.

Merchant Automotive is where I got mine. They're a great outfit. Their rebuilt transfer cases come with all the upgrades, including the pump rub kit.

My original failed though the rear output shaft seal. It happened right after the 5 year/100K ran out. The dealer had replaced this seal and the slip yoke six times under warranty. It turned out that they damaged the drive shaft when replacing a u joint under warranty at 12,000 miles. This caused a vibration issue at 68-80MPH. It had been back under warranty over and over and over. It was under warranty, so it was their problem, right? If I touched it, it became my problem. While inspecting the transfer case that had run dry, I saw the old hammer marks on the driveshaft tube. They were covered in a light surface rust like the rest of the drive shaft. I took it to my buddy, who has a monstrous driveshaft balancer. Just beginning to spin it up, I thought the massive balancer was going to walk across the room. Dealers suck. This was a big regional dealer with many commercial accounts. They'd wasted months of my time. I have a stack of warranty service invoices that looks like a ream of paper.

Thanks everyone