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Section F
36 - 1
Synchro Shuttle Gearbox -
4WD CANNOT BE ENGAGED
In normal operation the 2/4 wheel drive clutch is spring loaded off and therefore disengaged to give 2 wheel drive. The clutch
must be pressurised to give 4 wheel drive. Before starting the more detailed fault finding procedures - eliminate the obvious:
1
Check that the transmission oil level is correct.
2
Check that the fuse for the 2/4WD circuit is intact.
3
Check that the 4-wheel drive external pipework is not damaged and that the drive train is intact.
4
Check that all the electrical connections are clean and secure. Also check that the solenoid spool is not sticking (in the
2WD position).
5
Check that the mainline pressure is correct (see 'Low Mainline Pressure').
6
Check that the pump flow rate is correct.
If the fault is not rectified after eliminating the obvious, check the following:
Possible Cause
7
Low mainline pressure
8
Low mainline pressure (due to 2/4WD clutch):
8.1 2/4WD solenoid spool sticking.
8.2 2/4WD solenoid spool O-ring failed.
8.3 Clutch shaft sealing rings leaking.
8.4 Excessive clutch shaft end float.
8.5 Wrong type clutch piston fitted.
8.6 Clutch piston O-ring failed.
9
Defective 2/4WD clutch:
9.1 Worn friction/counter plates
9.2 Mechanical failure of 4WD unit
9.3 Incorrect clutch pack end float.
9803/3280
Transmission
Fault Finding
2/4 Wheel Drive Clutch
Purchased from www.WorkshopManuals.co.uk
Remedy
7
Identify if the fault is related to the 2/4WD
disconnect:
7.1 Disconnect the external pipework to the
2/4WD clutch. Cap and plug open orifices.
7.2 Check the mainline pressure - if the pressure
is correct, the fault must be within the 2/4WD
(see step 8). If the reading is still low check
the transmission in the normal manner.
8
Rectify fault:
8.1 Strip, clean and re-assemble solenoid valve,
renew valve if required.
8.2 Renew O-ring.
8.3 Renew clutch shaft sealing rings.
8.4 Rectify fault, renew parts as required, reset
end float (should not exceed 0.03 mm; 0.001 in)
8.5 Fit correct type clutch piston (ie, without bleed
hole).
8.6 Replace clutch piston O-ring.
9
Rectify fault:
9.1 Inspect friction/counter plates, renew as
required.
9.2 Strip and inspect 4WD unit. Check that the
electrical and hydraulic circuits are functioning
correctly.
9.3 Measure clutch pack end float (should be 1.0 to
2.3 mm). Correct as required.
Section F
36 - 1
Issue 1
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