JLG 680S, Service And Maintenance Manual, Page: 236 / 530

SECTION 3 - CHASSIS & TURNTABLE
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3.26 GM ENGINE GENERAL MAINTENANCE
Maintenance of the Drive Belt
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 in. (13mm). If the depression is more
than allowable adjust the tension.
THE ENGINE MANUFACTURER DOES NOT RECOMMEND THE USE OF "BELT
DRESSING" OR "ANTI SLIPPING AGENTS" ON THE DRIVE BELT.
Engine Electrical System Maintenance
The engine electrical system incorporates computers and
microprocessors to control the engine ignition, fuel control,
and emissions. Due to the sensitivity of the computers to good
electrical connections periodic inspection of the electrical wir-
ing is necessary. When inspecting the electrical system use the
following:
• Check and clean the battery terminal connections and
insure the connections are tight
• Check the battery for any cracks or damage to the case
• Check the Positive and Negative battery cables for any cor-
rosion build up, rubbing or chafing, check connection on
the chassis to insure they are tight
• Check the entire engine wire harness for rubbing chafing,
cuts or damaged connections, repair if necessary
• Check all wire harness connectors to insure they are fully
seated and locked
• Check ignition coil and spark plug cables for hardening,
cracking, chafing, separation, split boot covers and
proper fit
• Replace spark plugs at the proper intervals as prescribed in
the engine manufacturer’s manual
• Check to make sure all electrical components are fitted
securely
• Check the ground and platform control stations to insure
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 that you are not getting a false reading, make sure
the following steps are taken to before check the oil level.
1. Stop the engine if in use.
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.
Figure 3-115. Engine Oil Dip Stick