4T65E

Symptoms:

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

Cause:
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.

Correction:
Sonnax 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.

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. The Sonnax boost valve kit 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

Contents:

• Boost Valve & Sleeve Assembly

SONNAX Installation Instructions