Worn boost valve sleeve allows reverse oil leakage and worn end plug causes imbalance of pressure regulator valve
Ensure proper main regulator valve control with this boost valve and sleeve kit with O-ringed balance oil plug. Replaces '91 current OE boost valves.
Common problems in vehicles with a 4L80-E and 4L85-E transmissions are uncontrollable line rise (upward of 500-600 psi), high line pressure in reverse, buzzing noise, broken direct clutch drums and/or broken cases. These problems are usually caused by reverse boost oil that enters the torque signal circuit due to a wear-created cross leak at the sleeve. High line pressure and buzz is created by oil leakage past the aluminum balance plug. The Sonnax boost vavle kit 34200-03K eliminates these problems.
If you detect leakage between the sleeve and pump bore, use 34200-01K, which includes an O-ringed sleeve to compensate for pump bore wear and prevent pump scrappage.
February 21, 2013
Topics: Vacuum Testing Vacuum Test Guides Transmission GM 4L80-E TransmissionRead Now
Contact a Sonnax Parts Distributor.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.