JLG 660SJ Service Manual - Manual (Page 122)

SECTION 3 - CHASSIS & TURNTABLE
3-78 – JLG Lift – 3121298
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 belts check for:
• Cracks or breaks
• Chunking of the belt
• Splits
• Material hanging from belt
• Glazing and hardening
• Damaged or improperly aligned pulleys
• Improperly performing tensioner
Check 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 depression is more than
allowable, adjust 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 incorporates computers and
microprocessors to control engine ignition, fuel control, and
emissions. Periodic inspection of electrical wiring is necessary
due to sensitivity of computers to good electrical connections.
When inspecting the electrical system use the following:
• Check and clean battery terminal connections and ensure
connections are tight
• Check battery for any cracks or damage to case
• Check Positive and Negative battery cables for corrosion
build up, or rubbing and chafing. Check connections on
chassis are tight.
• Check entire engine wire harness for rubbing chafing, cuts
or damaged connections. Repair as needed.
• Check all wire harness connectors to ensure they are fully
seated and locked.
• Check ignition coil and spark plug cables for hardening,
cracking, chafing, separation, split boot covers, and fit
• Replace spark plugs at the proper intervals as prescribed 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, FLUCTUATION OR DROP IN OIL PRESSURE, AND ROCKER
ARM "CLATTER".
CARE MUST BE TAKEN WHEN CHECKING ENGINE OIL LEVEL. OIL LEVEL MUST
BE MAINTAINED BETWEEN "ADD" MARK AND "FULL" MARK ON 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 in use.
2. Allow sufficient time (approximately 5 minutes) for oil to
drain back into oil pan.
3. Remove dipstick. Wipe with a clean cloth or paper towel
and reinstall. Push dipstick all the way in dipstick tube.
4. Remove dipstick and note oil level.
5. Oil level must be between "FULL" and "ADD" marks.
Figure 3-94. GM Engine Oil Dip Stick
6. If oil level is below "ADD" mark, proceed 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 away
any excess oil.