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.