Caprice V8-307 5.0L (1987)
Torque Converter: All Technical Service Bulletins
A/T - Multiple Driveability Concerns
Number:
87-304-7A
Section:
7A
Date:
May, 1989
Subject:
POSSIBLE INOPERATIVE TORQUE CONVERTER OR RELATED CONDITION
Model and Year:
1985-87 PASSENGER CARS AND TRUCKS WITH THM 440T4 OR TRANSMISSIONS
TO:
ALL CHEVROLET DEALERS
Information is provided in this bulletin for evaluation of the 245 mm Torque Converter, diagnosis and possible Torque Converter failure used in THM
440-T4/HYDRA-MATIC 4T60 transaxles and THM 700-R4/HYDRA-MATIC 4L60 Transmissions.
CAUSES FOR A POSSIBLE TORQUE CONVERTER CONDITION ARE AS FOLLOWS:
-
A broken dampener plate rivet (inside the converter). These rivets hold the dampener assembly and the torque converter clutch apply plate
together.
-
Broken or loose spring tips. The springs are used on the dampener assembly to aid in torsional shock during TCC apply and reducing converter
clutch apply feel.
-
Converter pump vanes broken or loose.
-
Hydraulic leak due to worn or damaged seals.
-
Delamination of converter clutch apply plate fiber material.
THE FOLLOWING IS A LIST OF SYMPTOMS THAT A VEHICLE MAY EXHIBIT UPON OR DURING TORQUE CONVERTER OPERATION:
-
Shudder and/or Vibration during Torque Converter Clutch Apply.
-
No Upshift due to fiber material sticking valves and/or fiber material and metal particles in filter.
-
No Drive and/or Reverse.
-
Converter sprag inoperative (no torque multiplication).
-
Noisy converter bearings or excessive end play.
-
Pinging noise (constantly).
-
Vibration, out of balance, loose vanes (Noisy).
-
Vehicle may exhibit Shudder or no TCC apply. Torque Converter Clutch lining delaminating due to coolant contamination from transmission
cooler.
-
Torque Converter Clutch crowd shudder condition. This condition is caused by a leak in the TCC circuit which could cause increased slippage and
wear away the fiber lining on the TCC apply plate.
Possible causes for TCC circuit leakage include:
worn turbine shaft seals, TCC solenoid O-ring, valve body gaskets and auxiliary
valve body gaskets, worn TCC accumulator piston pin or seal.
-
TCC apply shudder caused by converter dampener plate not parallel.
-
A Whine noise when shifted into drive that may increase when brake torqued. Torque converter Whine is usually noticed when the vehicle is
stopped and when the transmission is in drive or reverse. The noise will increase when engine RPM is increased. The noise will stop when the
vehicle is moving and there is no torque multiplication (both halves of the torque converter are turning at the same speed) or when the torque
converter clutch is applied.
With foot on brake and Gear Selector in Drive, Depress accelerator to approximately 1200 RPM for no more than 6 Seconds (Stall Test). A Torque
Converter Noise increases under load.
IMPORTANT:
This noise should not be confused with pump whine noise which is usually noticeable in park, neutral and all other gear ranges.
Pump whine will vary with pressure ranges.
