• Erratic line pressure
  • Soft upshifts
  • Low line rise in Forward
  • Low line rise in Reverse


Bore wear near the small valve causes harsh or delayed Reverse depending on the location and severity of the leak, and the temperature wear near the end plug causes soft shift quality and low line rise.


Sonnax drop-in boost valve kit delivers oil 360° around the valve, reducing side-load. Also the surface contact of the spools is greater, which improves durability and reduces oil loss.


Boost Valve Kit
Part No. 84754-30K

You need this if... View Instructions Find a Distributor

Vehicles with GM 4T65-E transmissions often exhibit such problems as soft upshifts (especially 1-2), delayed Reverse and low line rise. This can be traced to wear of the OE boost sleeve assembly. The OE boost sleeve assembly consists of two steel valves and a steel plug that reside in the boost sleeve. The steel valves wear the aluminum sleeve and allow leakage of boost pressure. The OE boost assembly is not serviceable separately from OE, which forces the purchase of a new and expensive valve body. Sonnax boost valve kit 84754-30K replaces the worn OE parts and allows the OE valve body to be salvaged, restoring the hydraulic integrity of the circuit.

  • Hardcoat anodized aluminum valves combat premature wear
  • Valves are designed to increase oil lubricity, center the valves and increase longevity
  • Line boost valve is longer than the OE valve to increase wear surface area
  • Sleeve is made of highly wear-resistant aluminum and has been designed with oil channels to evenly distribute boost valve oil
  • Drop-in Zip Valve™ parts install quickly and easily
Learn More About Zip Valve™ Drop-In Repairs
  • Boost Valve & Sleeve Assembly

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

GM 4T65-E Valve Body Layout

GM 4T65-E Valve Body Layout

  • 4T65-E Boost Valve Kit 84754-30K
  • 4T65-E Boost Valve Kit 84754-30K
  • 4T65-E Boost Valve Kit 84754-30K details

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

4T65-E Boost Valve Kit Vacuum Test Locations