Pacific Performance Engineering 8L90 Transmission Thermal Bypass Valve for 2015–2018 Silverado/Sierra 1500 — 3/8" OE-fit

High-quality replacement thermal bypass valve engineered to manage transmission fluid flow for 2015–2018 Silverado/Sierra 1500 trucks with the 8L90 transmission and a 3/8" cooler line.

This PPE Power (Pacific Performance Engineering) transmission fluid thermal bypass valve is a direct-fit service part designed for 8L90-equipped 2015–2018 Silverado and Sierra 1500 trucks that use a 3/8" cooler line. It regulates when fluid is routed to the external cooler versus recirculated internally, helping the transmission reach and maintain optimal operating temperature during varying driving conditions. Built to meet OE-style fit and function, this valve is presented as a durable replacement component for technicians and DIY owners who need a reliable thermal control solution.

How does this bypass valve affect transmission temperature control?

The valve opens or closes based on fluid temperature so the transmission either sends oil through the external cooler or bypasses it back into the circuit. This helps the system avoid over-cooling in cold conditions and promotes efficient heat rejection when the fluid gets warm.

• Temperature-actuated valve operation tailored for 8L90 circuits.
• Direct replacement for OE-style flow management functions.
• Reduces unnecessary cooling during short trips or cold starts.
• Engages external cooler under load or high-temperature situations.

Will this part fit my 2015–2018 Silverado or Sierra 1500 with the 8L90 transmission?

Yes—this PPE Power valve is specified for Silverado and Sierra 1500 model years 2015 through 2018 that are equipped with the 8L90 transmission and use a 3/8" transmission cooler line. Installation requires matching the vehicle’s cooler line diameter and mounting location to ensure correct alignment and operation.

• Designed for 8L90 transmission applications in listed model years.
• Compatible with 3/8" cooler line plumbing used on these trucks.
• OE-style connections intended for straightforward installation.
• Verify vehicle build and factory cooler line size before ordering.

What are the practical benefits of replacing a worn thermal bypass valve?

Replacing a failing valve restores proper fluid routing which helps the transmission reach efficient temperature quicker and prevents excessive cooling or overheating under load. A functioning valve supports consistent hydraulic performance and can reduce strain on internal components caused by improper fluid temperatures.

• Improves thermal stability across varied driving conditions.
• Promotes correct hydraulic pressure and shift quality.
• Prevents extended operation with overly cool or overheated fluid.
• Helps protect internal transmission parts from temperature-related wear.

How difficult is installation and what should I prepare?

Installation is typically straightforward for anyone familiar with basic transmission cooler plumbing—expect to drain or cap lines, remove the old valve, and install the replacement with correct sealing and mounting. Use proper tools, inspect hoses and clamps, and follow a service manual or OEM guidance to ensure no leaks and correct routing.

• Basic hand tools and line-clamping or fluid-capture gear recommended.
• Inspect and replace worn hoses, clamps, or seals during service.
• Torque fittings per vehicle specifications to prevent leaks.
• Test drive to confirm proper warm-up and no leaks after installation.

Who this part is for: This PPE Power 125071000 thermal bypass valve is intended for automotive technicians, performance shops, and owners of 2015–2018 Chevy Silverado or GMC Sierra 1500 trucks with the 8L90 transmission and 3/8" cooler lines who need an OE-compatible replacement component. Choose this valve when you want a like-for-like repair item that restores correct fluid routing behavior, supports stable transmission operating temperatures, and fits directly into the factory cooler plumbing without major modifications.