Ready for Review s9

Ready for Review

► Automatic transmissions require periodic maintenance, which includes checking transmission fluid and replacing fluid and filters.

► If transmission fluid levels are low, identify the source of fluid loss.

► Visually inspect transmission fluid and replace as necessary.

► Diagnosis of transmission problems requires a thorough transmission inspection.

► Use extreme caution and wear proper protective clothing and equipment when diagnosing a transmission in a running vehicle.

► Diagnostic transmission tests include the fluid check, road test, visual inspection, scan of the computer for codes, stall test, hydraulic pressure test, leak check, pan inspection, air check, cooler flow test, and noise, vibration, and harshness test.

► Always perform a diagnostic test-drive under a range of operating conditions.

► Using a factory scan tool allows technicians bidirectional transmission control.

► Stall testing involves determining whether the engine can achieve manufacturer-specified rpm in each gear.

► Hydraulic system pressure testing should be performed via manufacturer-supplied test ports.

► In-vehicle transmission repairs include replacement of the vehicle speed sensor, extension housing bushing, and power train mount; repair of the valve body and the external gaskets and seals; and adjustments of the servo and bands.

► Leaks from gaskets or seals may require bushing replacement to properly repair the leak.

► Repair of power train mounts is critical for keeping the engine and transmission in proper position.

► Hydraulically controlled transmission vehicles will likely require a test-drive to determine functionality of the torque converter clutch.

► Adjust the shift linkage and transmission range sensor as part of automatic transmission servicing.

► Always follow safety precautions and wear personal protective clothing and equipment when removing the transmission for repair.

► Thoroughly inspect the flex plate, even though it is unlikely to need repair.

► If not replacing the torque converter, be sure to inspect the bolts, pump drive, pump drive tangs, pump drive lugs, and converter snout, and to check the end play.

► Always clean and inspect the transmission oil cooler and lines prior to installing a new or repaired transmission.

► Check bearings to ensure preload and end play are at optimum levels.

► Disassemble a transmission in a stepwise fashion to avoid missing transmission failure clues.

► Take care during transmission disassembly to not lose or damage any parts.

► Check planetary gear sets for discoloration, cracked or worn teeth, and end play.

► Inspect the smaller transmission parts, including bushings, thrust bearings, and washers.

► Disassemble and inspect one-way rollers for signs of damage.

► Visually inspect sprags, as they cannot be completely disassembled.

► All components of the oil delivery circuits must be inspected for debris, damage, and proper operation.

► Inspect the transmission case for damage or warping, and ensure the vent is unclogged.

► Inspect bands for damage, wear, or burns; inspect the drum for wear and warpage.

► Always rebuild clutch assemblies during transmission rebuilding, and thoroughly inspect all components for damage and wear.

► Measure clutch pack clearance after reassembly.

► Disassemble the transmission valve body, and inspect each valve for wear.

► Both gear-style and chain-style transaxle assemblies must be inspected for wear.

► Carefully reassemble the transmission in the correct sequence, with all components properly lubricated.

► Install the torque converter and ensure that all three components (oil pump drive, stator support, and turbine input shaft) engage with their mating parts.

► When finished, test-drive the vehicle and double-check the fluid level to ensure there are no leaks.