GM: Transmission Not Moving Or Excessive Slipping – UnderhoodService

GM: Transmission Not Moving Or Excessive Slipping

When a GM 6L80/90 transmission finds its way into your shop with a complaint of no forward or reverse movement, or is slipping badly in all ranges, initial inspection may reveal a cracked or split sump filter. However, filter quality may not be the underlying issue.

Models: GM Models with 6L80/90 transmissions

Condition

When a GM 6L80/90 transmission finds its way into your shop with a complaint of no forward or reverse movement, or is slipping badly in all ranges, initial inspection may reveal a cracked or split sump filter (see Figure 1). However, filter quality may not be the underlying issue.

Damage to the pump itself may be found upon disassembly of the transmission (see Figure 2). This damage can cause high-pressure spikes, which can force fluid into the filter neck and cause the filter to split or crack. When the filter is found in this condition, always check for pump damage as well as other possible internal distress.

Solution

To correct this issue, it is recommended to repair or replace of the damaged pump parts, or replacement of the pump assembly, along with installation of a new, high-quality sump filter.

Courtesy of Raybestos Powertrain

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