ZF Repair Manual: ZF63IV, ZF80IV, ZF80-1IV
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Repair Manual and Spare Parts List
Section 9: Troubleshooting
Symptom
Possibly cause
Remedy
7. No shifting pressure available
7.1 Direction of engine rotation does not
agree with arrow on transmission
7.2 No fluid in the transmission
7.3 Fine filter is dirty
7.4 Fluid level in transmission is too low
7.5 Fluid pump worn out
7.6 Fitting key in input shaft for fluid
pump drive is broken
7.7 Spring of shifting pressure Replace
control block relief valve is broken
7.1 Replace with engine of correct of rota-
tion
7.2 Refill with fluid
7.3 Replace fine filter
7.4 Top-up with fluid. In case of loss of
fluid check transmission, cooler and
pipelines for leakage and remedy
same, also refer to 10. through 13.
7.5 Replace control block
7.6 Remove control block
7.7 Replace fitting key, replace any other
faulty parts
8. Excessive fluid temperature
8.1 Fluid cooler is too small
8.2 Excessive fluid in transmission
8.3 Fluid cooler is dirty on water side
8.4 Worn fluid pump in control block
8.5 Faulty piston rings in control block
8.6 Clutch is slipping
8.7 Clutch does not open completely due
to worn disc support
8.8 Clutch does not open completely due
to worn disc support
8.9 With fluid cooler in bypass and unfa-
vorable arrangement of pipelines too
little coolant water flows through by-
pass to cooler
8.1 Use a larger fluid cooler
8.2 Remove excessive fluid with commer-
cial suction pump
8.3 Detach coolant water lines and clean
fluid cooler on water side
8.4 Replace control block containing fluid
pump
8.5 Remove control block, replace piston
rings. In case of wear in the control
block due to faulty piston rings re-
place control block as well
8.6 Refer to 3.
8.7 Dismount transmission and coupling,
replace all faulty parts
8.8 Dismount transmission, replace inner
disc support and/or clutch
8.9 Correct bypass pipeline
9. Water in the fluid, fluid looks milky
9.1 Fluid cooler faulty
9.2 High water level in engine compart-
ment, water entering through output
shaft seal
9.1 Repair leakage at cooler or replace
cooler. Change transmission fluid
9.2 Remedy cause for water level in en-
gine compartment change transmis-
sion
10. Fluid leakage at output shaft
10.1 Breather clogged with paint or dirt
10.2 Shaft seal faulty
10.1 Remove paint or dirt from breather
10.2 Disassemble transmission, replace
seal. If seal location on output shaft
is worn-seal lip should bemounted
offset
11. Fluid leakage at breather
11.1 Excessive fluid in transmission
11.1 Pump excessive fluid out with com-
mercial hand pump
12. Fluid leakage at joints
12.1 Bolts are not tight
12.2 Seals on bolts have been used sev-
eral times
12.3 Mating faces are contaminated, no
surface seal applied
12.1
Tighten bolts with prescri-bed torque.
12.2 Replace seals, tighten bolts with
prescribed torque
12.3 Unscrew housing half, finish mating
faces with oilstone or finishing file,
apply surface seal.
Assemble
trans-mission,
tighten
bolts with correct torque.