Air Checking Procedures
AUTOMATIC TRANSAXLE AIR CHECKING PROCEDURESCAUTION: PROTECT YOURSELF BY WEARING SAFETY GLASSES WHEN PERFORMING THE FOLLOWING PROCEDURES.
Before you begin:
- Regulate the shop air between 80 and 100 psi. Pressure less than 80 psi or higher than 100 psi may lead to a misdiagnosis.
- Inspect rubber-tipped nozzle to verify that it is in good condition.
CLUTCH AIR CHECK PROCEDURE
1. Remove valve body.
2. Place rubber-tipped nozzle in proper apply port pressing firmly to create a good seal between nozzle and apply port.
3. Apply air to hydraulic circuit and watch for clutch to move quickly.
IMPORTANT: A small amount of air bubbles coming from the lube holes of the clutch housing that is being air checked is normal.
4. After clutch has been applied, hold air nozzle tightly against port, forming a seal, and release trigger on air nozzle. While air nozzle is still held tightly against port, clutch should hold pressure for approximately one to two seconds before slowly releasing.
IMPORTANT: If no air leak at clutch can be found, leak is most likely not a cut/torn clutch piston, but is more likely one of the other potential causes listed in the section for the appropriate clutch in question.
5. Listen and look for leaks.
1ST CLUTCH HYDRAULIC CIRCUIT AIR CHECK
To air check 1st clutch hydraulic circuit, apply air to the 1st clutch apply pressure port. Because first clutch is hidden by the transaxle end cover, the clutch plates cannot be watched for proper apply. When applying first clutch, watch for the input shaft to move slightly, indicating the clutch has applied or listen for a quick "clunk" sound to verify that the clutch has applied. If there is any question whether first clutch is applying, bench test the clutch using an air check fixture, tool P/N SA9147T.
NOTICE: A large leak in 1st gear circuit can cause a loss of other forward gears.
If 1st clutch does not apply properly when performing the air check, possible sources of leakage include:
- Damaged 1st clutch piston (1).
- Worn or damaged input shaft hub seal ring(s) (2).
- Damaged servo piston cover O-ring (3).
1st Clutch
2ND/REV CLUTCH HYDRAULIC CIRCUIT AIR CHECK
To air check 2nd clutch hydraulic circuit, apply air to the 2nd clutch apply pressure port. When applying air to 2nd clutch, a small amount of cross leakage between 2nd and 3rd clutch is normal.This is due to a small amount of normal leakage around the input shaft feed tube bushing which is located between the 2nd and 3rd clutch.
If 2nd clutch does not apply properly when performing the air check, possible sources of leakage include:
- Damaged 2nd clutch piston (1).
- Worn or damaged input shaft hub seal ring(s) (2).
IMPORTANT: If air/bubbles are observed coming from the lube port when the 2nd clutch apply pressure port is pressurized, this may be an indication that the input shaft nut is loose or not properly seated.
Input shaft nut not torqued properly/not fully seated (3).
IMPORTANT: To verify that the bushing is at the correct depth, refer to Misplaced or Loose Input Shaft Inner Tube Bushing Check.
- Delivery tube bushing in input shaft mislocated or loose (4)
- Damaged clutch housing to input shaft O-ring under 2nd clutch (5).
- Damaged clutch housing to input shaft O-ring seal between 2nd and 3rd clutches (6).
- Input shaft inner tube retaining pin out of position/missing (7).
- Damaged input shaft inner tube O-ring seal (8).
- Damaged/missing delivery tube sleeve (9).
If the complaint is for reverse, inspect the forward/reverse servo piston following the procedures below in addition to the 2nd rev clutch hydraulic circuit procedures.
1. Plug off the reverse pressure from the forward/reverse servo to 2nd clutch apply port.
2. Place a rag over 1st, 3rd and 4th oil-to-servo piston port to avoid spray.
CAUTION: AS PRESSURE IS APPLIED TO THE REVERSE PRESSURE TO FORWARD/REVERSE SERVO PISTON PRESSURE PORT, AIR PRESSURE WILL CAUSE A SPRAY-BACK OF OIL OUT OF THE 1ST, 3RD AND 4TH OIL-TO-SERVO PISTON PORT. IN THE EVENT OF HOT TRANSAXLE OIL, THIS COULD RESULT IN PERSONAL INJURY.
3. Apply pressure to the reverse pressure to forward/reverse servo piston pressure port.
When following the above procedures, the forward/reverse servo piston should move, pulling the fork toward the reverse driven gear. If the forward/reverse servo piston does not apply properly, inspect for:
- Damaged forward/reverse servo piston cover O-ring (10).
- Damaged forward/reverse servo piston seal ( 11).
IMPORTANT: For detailed information on delay/harsh engagement into reverse, refer to Delay/Harsh Engagement Into Reverse Diagnostic Chart.
2nd/Reverse Clutch (in Reverse)
2nd/Reverse Clutch (in 2nd)
3RD CLUTCH HYDRAULIC CIRCUIT AIR CHECK
To air check 3rd clutch hydraulic circuit, apply air to the 3rd clutch apply pressure port. When applying air to 3rd clutch, a small amount of cross leakage between 3rd and 2nd clutch is normal. Second clutch should not immediately apply when applying air to the 3rd clutch apply port, while blocking the 2nd clutch apply port. However, it is normal for 2nd clutch to apply within 2-3 seconds after applying air to the 3rd clutch apply port when the 2nd clutch apply port is blocked. This is due to a small amount of normal leakage around the input shaft O-ring seal between the 2nd and 3rd clutch.
If 3rd clutch does not apply properly when performing the air check, possible sources of leakage include:
- Damaged 3rd clutch piston (1).
NOTICE: To verify that the bushing is at the correct depth refer to Misplaced or Loose Input Shaft Inner Tube Bushing Check.
- Delivery tube bushing in input shaft mislocated or loose (3).
- Damaged clutch housing-to-input shaft O-ring seal under 3rd clutch (4).
- Damaged clutch housing-to-input shaft O-ring seal between 3rd and 2nd clutches (5).
- Damaged input shaft inner tube O-ring seal (6).
- Damaged/missing delivery tube sleeve (7).
- Input shaft inner tube retaining pin out of position (8).
3rd Clutch
4TH CLUTCH HYDRAULIC CIRCUIT
To air check 4th clutch hydraulic circuit, apply air to the 4th clutch apply pressure port.
If 4th clutch does not apply properly when performing the air check, possible sources of leakage include:
- Damaged 4th clutch piston seal (1).
- Damaged/missing delivery tube sleeve (2).
- Damaged clutch housing-to-output shaft O-ring seal under 4th clutch (3).
- Delivery tube bushing in output shaft mislocated or loose (4).
- Output shaft tube retaining pin out-of-position (5).
- Damaged output shaft hub O-ring seals (6).
- Damaged output shaft tube seal ring (7).
- Output shaft check ball missing (9).
4th Clutch
TCC HYDRAULIC CIRCUIT
The TCC circuit cannot be checked reliably using air with the exception of checking for a missing input shaft check ball (3) or checking for a leaking Teflon_ seal that separates lube from TCC disable (4).
IMPORTANT: When applying air to the lube pressure port, a small amount of leakage will normally be observed coming from TCC disable and/or converter out. If a gross leak is observed, inspect for a missing input shaft check ball (3) or leaking Teflon_ seal that separates lube from TCC disable (4).
To check for a missing input shaft check ball (3) or a leaking Teflon-seal that separates lube from TCC disable (4), regulate air pressure to 25 psi. Apply air to the lube pressure port (next to TCC apply) and look for a significant amount of air coming from TCC disable or converter out ports.
Other sources of leaking in the TCC circuit, which cannot be detected with an air check include:
- Damaged input shaft seal ring(s) between TCC disable and lube or converter out (1), (4).
- Damaged input shaft to converter O-ring (2).
TCC