JLG 450A_AJ Series II Service Manual - Manual (Page 170)

SECTION 3 - CHASSIS & TURNTABLE
3-120 – JLG Lift – 3121180
3.17 GM ENGINE GENERAL MAINTENANCE
Drive Belt Maintenance
The serpentine drive belt utilizes a spring loaded tensioner
which keeps the belt properly adjusted. The drive belt is
an integral part of the cooling and charging systems and
should be inspected frequently.
When inspecting the belts check for:
• Cracks or breaks
• Chunking of the belt
• Splits
• Material hanging from the belt
• Glazing and hardening
• Damaged or improperly aligned pulleys
• Improperly performing tensioner
Check the belt tensioner by pressing down on the midway
point of the longest stretch between pulleys. The belt
should not depress beyond 1/2 inch (13mm). If the
depression is more than allowable adjust the tension.
ENGINE MANUFACTURER DOES NOT RECOMMEND USE OF
“BELT DRESSING” OR “ANTI SLIPPING AGENTS” ON DRIVE
BELT.
Engine Electrical System Maintenance
The engine electrical system uses computers and micro-
processors to control engine ignition, fuel control, and
emissions. Periodic inspection of electrical wiring is
required due to sensitivity of computers to good electrical
connections. When inspecting electrical system:
• Check and clean battery terminal connections and
ensure connections are tight.
• Check battery for any cracks or damage to the case.
• Check positive and negative battery cables for corro-
sion, rubbing, or chafing. Check connection to chassis
is tight.
• Check entire engine wire harness for rubbing chafing,
cuts, or damaged connections. Repair as needed.
• Check all wire harness connectors are fully seated and
locked.
• Check ignition coil and spark plug cables for harden-
ing, cracking, chafing, separation, split boot covers
and proper fit.
• Replace spark plugs at the proper intervals as pre-
scribed in the engine manufacturer’s manual.
• Make sure all electrical components are fitted securely.
• Check ground and platform control stations to ensure
all warning indicator lights are functioning.
Checking/Filling Engine Oil Level
AN OVERFILLED CRANKCASE (OIL LEVEL OVER THE SPECIFIED
FULL MARK) CAN CAUSE AN OIL LEAK, A FLUCTUATION OR
DROP IN THE OIL PRESSURE, AND ROCKER ARM “CLATTER” IN
THE ENGINE.
CARE MUST BE TAKEN WHEN CHECKING THE ENGINE OIL LEVEL.
OIL LEVEL MUST BE MAINTAINED BETWEEN THE “ADD” MARK
AND “FULL” MARK ON THE DIPSTICK.
To ensure you are not getting a false reading, make sure
the following steps are taken before checking oil level.
1. Stop engine if running.
2. Allow sufficient time (approximately 5 minutes) for
the oil to drain back into the oil pan.
3. Remove the dipstick. Wipe with a clean cloth or
paper towel and reinstall. Push the dipstick all the
way into the dipstick tube.
4. Remove the dipstick and note the oil level.
5. Oil level must be between the “FULL” and “ADD”
marks.
6. If oil level is below the “ADD” mark, go to Step 7 and
8 and reinstall dipstick in dipstick tube.
7. Remove oil filter cap from valve rocker arm cover.
8. Add required amount of oil to bring level up to, but
not over, “FULL” mark on dipstick.
9. Reinstall oil fill cap to valve rocker cover and wipe off
excess oil.
Figure 3-76. Engine Oil Dip Stick