M/T - Pops out of 3rd Gear on Accel or Decel
88chevy06Number: 88-145-7B
Section: 7B
Date: FEB., 1988
Subject: 3RD GEAR HOP-OUT
(2ND GEAR ON THE GEAR SHIFT KNOB)
Model and Year: 1985/88 LIGHT DUTY TRUCK WITH HM-117 MM
OR CH/SM 465 MANUAL TRANSMISSION
TO: ALL CHEVROLET DEALERS
Some 1985-88 R/V and C/K Trucks equipped with a HM-117 (CH/SM 465 in 1985-88 P-chassis vehicles) 4-speed manual transmission may exhibit 3rd gear hop-out on acceleration or deceleration.
If 3rd gear hop-out occurs, it can be repaired by installing the service part package listed below.
SERVICE PARTS INFORMATION:
P/N 8672944 Service Part Package contents:
Quantity Part Description
1 3rd Speed Gear
1 3rd-4th Synchronizer Hub
1 3rd-4th Speed Synchronizer Sleeve
2 3rd and 4th Speed Blocker rings
3 Synchronizer Keys
2 Synchronizer Springs
Refill the transmission with only SAE 80W-90 gear lubricant. Do not use automatic transmission fluid or engine oil. This will cause foaming out of the vent and possible reduced durability.
Refer to the Unit-Repair Section of the appropriate Service Manual for the procedures.