Merchant Automotive Transfer Case Pump Upgrade and Repair Kit | Gas


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Transfer Case Pump Upgrade and Repair Kit | Gas
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Product Information

The Merchant Automotive Transfer Case Pump Upgrade is the best upgrade you can perform on your 1998 to early-2007 GM transfer case by completely preventing the ever increasing problem of pump rub and catastrophic transfer case fluid loss. The basic kit can be installed proactively in a transfer case that has not yet succumb to a pump rub failure as a preventative maintenance measure. If your transfer case has already had a pump rub failure the MA Transfer Case Pump Upgrade can be installed as part of your repair to prevent future failure.

This kit is designed to include the parts necessary to perform an upgrade and repair to a transfer case that has suffered a pump rub failure requiring replacement of the rear case half for vehicles using the NP136, NP149, NV149, NP236, NP246, NP261, NP261HD, NP263 and NP263HD transfer cases with gas engines. Note that transfer cases operated without lubrication may also have additional internal damage that will not be evident from external inspection and could require additional parts. When properly installed this kit is backed by a Limited Lifetime Warranty against pump rub failure from Merchant Automotive.

To view/download installation instructions click here.

To view the Merchant Automotive installation Video click here.

To view the Truck U segment on the Merchant Automotive Transfer Case Pump Rub kit click here.

What is a Transfer Case "Pump Rub" Failure?

GM transfer cases used from 1998 through early 2007 use a gear pump inside the case that is driven off the mainshaft. The pump forces oil to the planetary as well as the drive sprocket sleeve. Because the pump is driven by the shaft, the housing of the pump must "float" in the rear housing. There are tabs around the pump housing that fit into spots in the rear housing to locate the pump housing and prevent it from spinning inside the case with the mainshaft. Over time, the pump tabs can start to wear on the rear housing. GM installed a spring steel clip in the housing intended to prevent wear, but the clip can break and be rendered useless.

Since the pump housing is aluminum and is a harder material then the magnesium rear housing, it can wear a hole in the rear housing and cause a very small leak. This leak is frequently high enough on the case that it typically will not leak when vehicle is not moving and therefore not leaving any drops on the ground; it will however leak while the vehicle is in motion. Unfortunately since the transfer case does not have a low fluid indicator the pump rub failure is often not found until there is transfer case damage from running the case out of fluid.

Avoid costly repairs to your transfer case by preventing "Pump Rub" by installing a Merchant Automotive Transfer Case Pump Upgrade kit in your transfer case today, before it happens to your vehicle.

With installation of this kit, you will have a LIMITED LIFETIME WARRANTY against pump rub. If your case ever wears a hole in the new rear housing with the upgrade installed. We will buy you a new transfer case. The MA Lifetime Warranty will only apply to installations with a new rear housing.


What do I do with the OEM anti rattle clip when installing this upgrade?

Discard the factory clip during installation of the MA Transfer Case Pump Upgrade kit. It's been designed and precision machined to work with the clip removed.

What other parts will I need to install this upgrade and repair kit?

We tried to make the kit all inclusive for an upgrade and repair installation after pump rub failure has occurred without including internal parts (like bearings, shafts, planetary gears, etc...) that may not necessarily be required. Unfortunately there is no real way to know the extent of the damage inside the case until it is completely disassembled. In many instances, as long as the case has not run out of fluid, it can be repaired with the new rear housing and components included in this kit to prevent pump rub from ever happening again. Be sure to refill the transfer case with the Merchant Automotive Performance Transfer Case Fluid included in this kit for excellent lubrication and performance and replace your original drain and fill plugs with the Merchant Automotive Magnetic Drain Plug kit also included with this kit as an additional layer of protection to catch metal debris from the fluid circulating inside the transfer case as well as replacing the factory plugs which are often rounded off or damaged.

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 causing the bearing to move out of proper alignment. Verify that the snap ring is fully engaged and properly 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 is often accompanied by a low speed grinding noise and is frequently caused by the rear output bearing snap ring not being fully seated causing the bearing to move out of proper alignment. Verify that the snap ring it fully engaged and properly seated in the rear housing and the locating groove in the bearing.

1998-2007SILVERADO/SIERRA1500, 1500HD, 2500, 2500HD, 3500NP246, NP261HD, NP263HD
1999-2007ESCALADE, ESV, EXTALLNP149, NP246
2002-2007AVALANCHE1500, 2500NP149, NV149, NP246, NP261, NP263, NP263HD
1500, 2500NP246



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