JLG 4017PS Service Manual - Manual (Page 120)

Engine
7-4 3706PS, 3707PS, 4014PS, 4017PS, 33.7, 37.6, 37.7
7.4 ENGINE COOLING SYSTEM
7.4.1 Surge Tank Cap
A 1 Bar (14.5 psi) cap is used on the surge tank. An
incorrect or malfunctioning cap can result in the loss of
coolant and a hot running engine.
7.4.2 Thermostat Replacement
Before considering thermostat replacement, check the
coolant level, fan belt tension and instrument cluster
temperature indicator.
• If engine seems to take a long time to warm up,
thermostat may be stuck in the open position and
requires replacement.
• If engine runs hot, check temperature of upper
radiator hose.
• If hose is not hot, thermostat may be stuck in
closed position.
• If engine has overheated, performance may
suffer, indicating other damage including
a leaking cylinder head gasket, cracked
cylinder head or block, and/or other internal
engine damage.
a. Thermostat Removal
1. Park machine on a firm, level surface, level machine,
fully retract boom, lower boom, place transmission
control lever in the (N) NEUTRAL position, engage
parking brake, and shut engine OFF.
2. Place a Do Not Operate Tag on both ignition key
switch and steering wheel.
3. Open engine cover. Allow system fluids to cool.
4. Properly disconnect battery.
5. Slowly turn surge tank cap to first stop and allow any
pressure to escape. Remove surge tank cap.
6. Place a funnel at base of radiator to channel drained
coolant into container. Loosen the drain plug and
slowly remove to allow coolant to drain. Transfer
coolant into a properly labeled container. Dispose of
properly if coolant needs to be replaced. Replace the
radiator drain plug.
7. Remove capscrews securing thermostat housing (1)
to engine.
8. Remove thermostat housing, old gasket and
thermostat. Clean all gasket surfaces. DO NOT let
any debris into thermostat opening.
Note: ALWAYS use correct thermostat and install a new
gasket. NEVER operate engine without a thermostat, or
engine damage will result.
b. Thermostat Installation
1. Install engine thermostat, thermostat gasket and
thermostat housing. Secure with the previously
removed capscrews.
2. Properly connect battery.
3. Open surge tank cap, and fill the radiator completely
with a 50/50 mixture of ethylene glycol and water.
Add coolant solution at a maximum rate of 1.3
gallons per minute (5 liters per minute). Replace and
tighten radiator cap. Add coolant to surge tank until
1/4 to 1/2 full. This overfilling will compensate for any
air trapped in cooling system.
4. Run engine to operating temperature. Visually check
for leaks with engine running. Check coolant level in
surge tank and fill, or drain, as necessary.
5. Close and secure engine cover.
6. Remove Do Not Operate Tags from both ignition key
switch and steering wheel.
MZ6540
1
TYPICAL THERMOSTAT