BD Diesel 1061531 8L90 Cooler Bypass Delete for 19-23 Silverado/Sierra 1500

Vehicle Fitment

• 2019-2021 Chevrolet Silverado 1500/GMC Sierra 1500 (4.3L Gas, 8L90)
• 2019-2023 Chevrolet Silverado 1500/GMC Sierra 1500 (5.3L Gas, 8L90)

Fitment Notes

• Fits GM 8L90 transmissions with 1/2" cooler lines only
• Replaces OEM part numbers 85048209, 84443930, 84963102, 84969051

Features

• Eliminates the factory transmission cooler bypass valve
• Forces 100% fluid flow through the external transmission cooler at all times
• Keeps transmission temperature at its lowest possible operating point
• Removes a known failure-prone component in the 8L90
• Includes all new seals required for installation
• Includes magnetic service plug

Specifications

• Transmission: GM 8L90
• Cooler line size: 1/2"
• Replaces OEM: 85048209, 84443930, 84963102, 84969051

Included Components

• 1x Transmission oil cooler bypass eliminator kit
• New seals for installation
• 1x Magnetic service plug

Product Description

The BD Diesel Cooler Bypass Delete (1061531) addresses a known weak point in the GM 8L90 8-speed automatic: debris can jam the internal bypass valve in recirculation mode, starving the external transmission cooler and letting fluid temperatures climb toward premature failure. This kit eliminates the bypass valve entirely, forcing 100% of transmission fluid through the external cooler at all times.

It's a simple, low-cost fix that removes a failure-prone factory component rather than waiting for it to cause a problem, and comes with all new seals and a magnetic service plug for a clean install. For 2019-2023 Silverado/Sierra 1500 owners running the 4.3L or 5.3L gas engine with the 8L90, it's a preventive upgrade that keeps the transmission running at its coolest possible operating temperature.