ZF Repair Manual: ZF63IV, ZF80IV, ZF80-1IV
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Repair Manual and Spare Parts List
Section 9: Troubleshooting
Symptom
Possibly cause
Remedy
13. Transmission noise becomes lou-
der
13.1 Fluid level too low so
that pump
sucks in air.
13.2 Damage starting on flexible coupling
due to wear or fatigue, possible due
to misalignment between engine
and transmission.
13.3 Beginning damage of bearings in
transmission, e.g. due to torsional vi-
brations, running without fluid, over-
load, wrong alignment of transmis-
sion excessive engine output
13.4 Beginning damage of gearings, e.g.
due to torsional vibrations, running
without fluid, overload
13.5 Fluid suction pipe in transmission
has come Ioose
13.1 Top up with fluid to marking on dip-
stick.
13.2 Replace flexible coupling.
Check alignment between engine
and transmission.
13.3 Disassemble transmission, replace
bearings concerned and other faulty
parts. Find causes and remedy.
13.4 Disassemble transmission, remove
faulty parts.
13.5 Disassemble transmission, fix fluid
suction pipe.
14. Chattering transmission noise
mainly at low engine
14.1 The engine or propeller generate tor-
sional vibrations in the drive unit
which produce a "chattering" noise
in the transmission
14.2 Misaligned cardan shafts on input or
output
14.1
Mount a flexible coupling with another
stiffness factor between enging and
transmission; a coupling with a higher
stiffness factor might be sufficient.
Otherwise analyse the torsional vibra-
tions to find out the required stiffness
for the coupling.
14.2 Mount and align cardan shaft strictly
according to instructions issued by
cardan shaft manufacture
15. Low pressure
15.1 Fine filter is dirty
15.2 Fluid level in transmission is low
15.3 Control block is broken
15.4 Problem at control valve
15.5 Piston rings on input shaft
are faulty
15.6 Piston rings inside the clutch
are faulty
15.7 Defective cover filter : air suction
15.8 Oil suction hose not properly
adjusted
15.9 Fitting key in input shaft for fluid
pump drive is broken
15.10 Possible wear of the piston ring
grooves
15.1 Replace fine filter
15.2 Refill with fluid
15.3 Replace control block
15.4 Replace control block
15.5 Remove control block and replace
piston rings
15.6 Disassemble transmission, replace
piston rings
15.7 Replace cover filter
15.8 Replace the seal and adjust cor-
rectly the suction hose
15.9 Remove control block replace fit-
ting key, replace any other faulty
parts
15.10 Replace the input shaft
16. Oil leakage
16.1 Porosity
16.2 Seals
16.3 Joints
16.4 Bracket with flatness error
16.5 Bolts are not tight
16.6 Fittings loosen
16.7 Dipstick is not tight
16.8 Filter is not tight
16.9 Excessive fluid in transmission
16.10 Breather clogged with paint or dirt (
fluid leakage at output shaft )
16.11 Aluminium washers used more
times
16.1 Replace faulty parts
16.2 Replace seals
16.3 Check if bolts are tighten with the
correct torque. Clean the surface
and reseal with Loctite 518
16.4 Replace bracket
16.5 Reseal and tighten bolts with pre-
scribed torque
16.6 Tighten or replace
16.7 Tighten dipstick or replace o-ring
dipstick
16.8 Tighten filter or replace o-ring filter
16.9 Remove excessive fluid with com-
mercial suction pump
16.10 Remove paint or dirty from
breather
16.11 Replace aluminium washers