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The Merchant Automotive Transfer Case Pump Upgrade and Repair Kit is for gas engine GM trucks and SUVs with 1998-early 2007 transfer cases that have suffered a pump rub failure and need a new rear case half. It includes our Transfer Case Pump Upgrade Kit, a new OEM magnesium rear transfer case housing, the seals, snap ring and grommet for the rebuild, our magnetic drain plug kit, 2 quarts of our performance transfer case fluid and lock ring pliers. It covers vehicles using the NP136, NP149, NV149, NP236, NP246, NP261, NP261HD, NP263 and NP263HD transfer cases with gas engines (4.3L, 4.8L, 5.3L, 6.0L and 8.1L).
Gas engines only. For 2001-2007 Duramax trucks with the 261XHD or 263XHD, see the XHD Pump Upgrade and Repair Kit.
Features
- Merchant Automotive billet T-6061 aluminum CNC machined transfer case pump housing
- New OEM magnesium rear transfer case housing
- Rear output seal, pickup tube seals, speed sensor seal, snap ring and grommet
- Magnetic drain plug kit and 2 quarts of performance transfer case fluid
- Lock ring pliers included
- Limited lifetime warranty against pump rub when properly installed
What's Included
- (1) Merchant Automotive Transfer Case Pump Upgrade Kit (10001): billet pump housing, transfer case adapter gasket, RTV silicone with applicator nozzle and blue threadlocker
- (1) OEM magnesium rear transfer case housing, 246/261HD/263HD (30961)
- (1) A13 rear output seal (22507)
- (1) B30 38 spline pickup tube seal (411330)
- (1) Pickup tube O-ring (12478088)
- (1) Speed sensor seal (10238)
- (1) Output shaft bearing snap ring (10198)
- (1) Snap ring hole grommet (88958815)
- (1) Merchant Automotive Magnetic Drain Plug Kit (10185)
- (1) Merchant Automotive Performance Transfer Case Fluid, 2 Qt (10193)
- (1) 9" lock ring pliers
What is a Transfer Case "Pump Rub" Failure?
GM transfer cases used from 1998 through early 2007 have a gear pump inside the case that is driven off the mainshaft. The pump sends oil to the planetary and the drive sprocket sleeve. Because the pump is driven by the shaft, the pump housing must "float" in the rear housing. Tabs around the pump housing fit into spots in the rear housing to locate it and keep it from spinning with the mainshaft. Over time, the pump tabs can wear on the rear housing. GM installed a spring steel clip in the housing to prevent wear, but the clip can break.
The aluminum pump housing is harder than the magnesium rear housing, so it can wear a hole in the rear housing and cause a small leak. The leak is often high enough on the case that it does not drip when the vehicle is parked, but it leaks while driving. Because the transfer case has no low fluid indicator, pump rub is often not found until the case has been damaged from running low on fluid.
With installation of this kit, you will have a LIMITED LIFETIME WARRANTY against pump rub. The MA Lifetime Warranty will only apply to installations with a new rear housing.
Vehicle Applications
| Year | Vehicle | Chassis | Transfer Case Model |
|---|---|---|---|
| 1998-2007 | Silverado / Sierra | 1500, 1500HD, 2500, 2500HD, 3500 | NP246, NP261HD, NP263HD |
| 1998-2003 | Blazer / Jimmy / S-10 / Sonoma | All | NP236 |
| 1999-2005 | Astro / Safari | All | NP136 |
| 1999-2007 | Escalade, ESV, EXT | All | NP149, NP246 |
| 2002-2007 | Avalanche | 1500, 2500 | NP149, NV149, NP246, NP261, NP263, NP263HD |
| 1998-2007 | Suburban / Yukon XL, Tahoe / Yukon | 1500, 2500 | NP246 |
Before You Order
- Gas engines only: Duramax trucks use the 261XHD and 263XHD; see the XHD Pump Upgrade and Repair Kit.
- Internal damage: a transfer case that has run without fluid may have internal damage that is not visible from the outside and may need additional parts.
- Need the seal driver? See the Pump Upgrade and Repair Kit with Seal Driver, Gas.
Installation Tips
- Discard the OEM anti rattle clip. The pump upgrade is designed and machined to work with the clip removed.
- The drain and fill plugs use pipe threads. Tighten them snug only, with new Teflon sealing tape on the threads.
- Make sure the rear output bearing snap ring is fully seated in the rear housing and in the locating groove of the bearing.
Installation Resources
- Installation Instructions (PDF)
- Mechanics Minute: Transfer Case Pump Upgrade Install (Merchant Automotive YouTube)
- Truck U Segment on the Merchant Automotive Transfer Case Pump Rub Kit
Related Parts
- Merchant Automotive HD Transfer Case Rear Output Seal Driver
- Deluxe Seal Kit, 263HD Transfer Case
- Transfer Case Housing Bolt Kit
Frequently Asked Questions
What do I do with the OEM anti rattle clip?
Discard the factory clip. The MA Transfer Case Pump Upgrade is designed and precision machined to work with the clip removed.
What other parts will I need?
We tried to make the kit all inclusive for an upgrade and repair after a pump rub failure, without including internal parts (bearings, shafts, planetary gears, etc.) that may not be needed. There is no way to know the extent of the damage until the case is fully disassembled. In many cases, as long as the case has not run out of fluid, it can be repaired with the new rear housing and the components in this kit.
I hear a grinding noise at low speed after installing the kit. What could that be?
A low speed grinding noise is most commonly caused by the rear output bearing snap ring not being fully seated, which lets the bearing move out of alignment. Verify that the snap ring is fully engaged and seated in the rear housing and the locating groove in the bearing.
What would cause a speed sensor correlation code after installing this upgrade?
A speed sensor correlation code often comes with a low speed grinding noise and is frequently caused by the same rear output bearing snap ring not being fully seated.
For warranty information, see our Warranty Policy.