-4-
Model T31643 (Mfd. 9/19)
Symptom
Possible Cause
Possible Solution
Forks will not lift
to max height.
1. Hydraulic oil low.
1. Fill pump assembly with hydraulic oil.
Forks do not lift. 1. Hydraulic oil low/contaminated.
2. Too much hydraulic oil in pump assembly/air
in hydraulic system.
3. Pump valve nut too tight.
1. Fill pump assembly with hydraulic oil. If necessary,
drain old/contaminated oil and replace.
2. Pump off extra hydraulic oil/air.
3. Loosen pump valve nut.
Forks do not
lower.
1. Lifting components jammed with debris.
2. Pump valve nut too loose.
3. Lifting components bent/damaged.
1. Inspect mechanism, clear debris.
2. Tighten pump valve nut.
3. Inspect/replace damaged lifting components.
Forks lower by
themselves.
1. Impurities in relief valve/hydraulic oil.
2. Relief valve faulty/damaged.
3. Seals worn/damaged.
1. Clean relief valve/change hydraulic oil.
2. Inspect/replace.
3. Inspect/replace.
Forks lower too
slowly.
1. Pump valve nut misadjusted.
1. Tighten pump valve nut.
Forks lower too
quickly.
1. Pump valve nut misadjusted.
1. Loosen pump valve nut.
Oil leaks.
1. Relief valve damaged.
2. Oil fill plug gasket damaged.
3. Seals worn/damaged.
4. Cracked/worn/damaged parts.
1. Inspect/replace.
2. Inspect/replace.
3. Inspect/replace.
4. Inspect/replace.
Troubleshooting
3. Replace lower plug and add replacement oil
to upper fill hole until level reaches bottom of
hole.
4. Without replacing fill plug, pump one lift
handle 10–15 times to expel any trapped air.
5. Replace fill plug and clean up any hydraulic
oil residue. Old oil can be stored in a sealable
metal or thick plastic container and recycled
at a recycling center near you.
2. Remove both hydraulic cylinder plugs (see
Figure 10) and allow oil to drain completely.
Figure 10. Hydraulic cylinder plug locations.
Pump valve nut on the back of the hydraulic cyl-
inder controls how open the pump valve is (see
Figure 9). If the nut is too loose, the forks will not
lower correctly, and if too tight, they won't lift.
Changing Hydraulic Oil
Hydraulic oil in the cylinder may need to be added
periodically after prolonged use or if it leaks
noticeably. We recommend ISO 32 or 46 grade
hydraulic oil.
To add hydraulic oil:
Adjusting Pump Valve Nut
1. Lower forks completely.
Figure 9. Pump valve nut location.
Pump Valve Nut
