Fluid Leak Diagnosis - Pontiac Fiero 1988 Service Manual

ON-VEHICLE SERVICE
7A1-3
c. Observe 2-1 downshift.
• Accelerate car to 20 mph (32 km/h).
• Quickly open the throttle to wide
open and observe downshift.
• Place gear selector into "D".
• Accelerate car to 50 mph (80 km/h).
• Close throttle, move gear selector to
"2" and observe downshift.
3. "LOW" range (L or 1) — 2nd and 3rd gear
should be inoperative. Do not overspeed engine.
a. Observe 2-1 downshift.
b. Place gear selector into "2" and accelerate
to 40 mph (64 km/h).
c. Close throttle and move gear selector into
" 1 " . The 2-1 downshift should occur
between 25-45 mph (40-72 km/h).
4. "REVERSE" (R)
a. Place gear selector into "R" and observe
reverse.
b. Do not place gear selector into "R" while
vehicle is moving.
FLUID P R E S S U R E T E S T PROCEDURE
1. Install pressure gage J 21867. See Hydraulic
Diagnosis.
2. Note transmission model code and refer to
Hydraulic Diagnosis.
CAUTION: To avoid possible personal
injury and/or damage to the car, brakes
must be applied at all times during the
test.
Causes of Low Oil Pressure
1. Low oil level.
2. T.V. system (pressure low in "Neutral",
"Drive", and low to normal in "Intermediate"
and "Reverse").
• T.V. cable misadjusted, sticking or bro-
ken.
• T.V. linkage binding or incorrect cable.
• Throttle valve stuck.
• Manual valve stuck.
3. Oil strainer plugged or damaged.
4. Oil strainer seal leaking.
5. Fluid contaminated or lost viscosity.
6. Control valve spring weak.
7. Control valve and pump bolts loose.
8. Control valve assembly:
• Check ball missing or off location.
• Stuck or damaged valves:
— T.V. valve and plunger.
— Shift T.V. valve
— Pressure regulator valve
— T.V. valve loose
— Pressure relief valve
• 1-2 accumulator piston and/or seal leaking
or missing.
• Internal leaks.
9. ("Low" only) Low blow off valve damaged,
check ball missing or off location.
10. ("Reverse" only) Low-Reverse clutch housing
to case cup plug assembly leaking. Low-
Reverse oil pipe or seal leaking.
11. Pump vane seals cut or missing.
12. Intermediate oil passages to pressure regulator
blocked.
13. Drive sprocket support to case cover leaking.
Causes of High Oil Pressure
1. T.V. system (pressure high in "Neutral" and
"Drive" and normal to high in "Intermediate"
and "Reverse")
• T.V. cable misadjusted, sticking or
broken.
• T.V. linkage binding or incorrect cable.
• Throttle valve stuck.
• Shift T.V. valve stuck.
• T.V. lifter bent, damaged or too short.
2. Control Valve and Pump Assembly
• T.V. valve and plunger
• Shift T.V. valve
• Pressure regulator valve
• T.V. valve loose
• Pump slide stuck
3. Low blow-off valve stuck closed ("Low" only).
4. Internal pump or case cover leaking.
FLUID LEAK DIAGNOSIS
Most fluid oil leaks are easily located and
repaired by visually finding the leak and replacing or
repairing the necessary parts. On some occasions a
fluid leak may be difficult to locate or repair. The
following procedure may help in locating and repair-
ing most leaks.