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GM Transfer Case - Averting Disaster

Mandatory ’01 to ’07 GM Transfer Case Fix

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Any time a catastrophic failure can be avoided by performing a simple upgrade, it’s worth looking into. Nickel and dime precautions taken now can save you big money and plenty of headaches later on. This month, we’re exposing a common problem found in the NP261XHD and NP263XHD transfer cases found in four-wheel-drive ’01 to ’07 Chevy and GMCs (and basically every four-wheel-drive GM from ’98 to ’07). It’s the kind of problem we’ve all grown to hate: It’s inevitable, and it surfaces without you knowing it.

Pump Rub
Within the NP261XHD and NP263XHD transfer cases, a gear pump is used to supply pressurized oil to the planetary gearset and drive sprocket sleeve. Due to the pump being driven off the output shaft, its housing floats inside the rear housing of the transfer case. Over time, one of the five indexing tabs on the pump housing wears through the factory- installed anti-rattle clip (used to fill in the tolerance between the pump housing and the transfer case housing) or effectively uses it to dig into the transfer case housing. This friction is often referred to as pump rub, and it eventually leads to a small hole in the transfer case, followed by a fluid leak. But due to the location of the hole, fluid won’t escape unless the truck is moving. So the problem is hard to detect and is usually discovered after the transfer case has been damaged from lack of lubrication.

Proactive Fix
With a reputation for bulletproofing virtually every aspect of Duramax-powered Silverados and Sierras, Merchant Automotive came up with a simple, affordable fix for the pump rub issue. The company developed an improved pump housing and now offers an all-inclusive upgrade kit for less than $100. Follow along as we install it in an electronically shifted, NP263XHD transfer case.

SOURCES
Merchant Automotive
100 N Fairview Rd Suite 30
Zeeland
MI  49464
866-399-7169
www.merchant-automotive.com
Flynn's Shop
Alexander
IL
217-478-3811
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