Yanmar 4JH4E - Page 252

6. Fuel Injection equipment
232
5) Wax type Cold Start Device (W-C.S.D.)
This device aids the easier start of engine by advancing the fuel injection timing, when the weather
is cold.
The wax element is integrated into the body of W-C.S.D. The engine coolant is led to the wax
element and flowing around it. The wax element is expanded by sensing the temperature of engine
coolant and moves the W-C.S.D piston. The movement of W-C.S.D piston turns the pump side
lever pin via lever shaft. This pin is connected to the roller holder against cam disc. The movement
of W-C.S.D piston changes the fuel injection timing by changing the phase angle between cam disc
and roller holder.
When the engine coolant is below - 10 degrees centigrade, the wax element becomes most
shrunken state; the roller holder comes to the maximum advance angle position (6.8 degrees of
crankshaft). When the engine coolant becomes warmer, the wax element expands gradually. The
roller holder turns from maximum advance angle position to smaller advance angle position. When
the temperature becomes over 56 degrees centigrade, the advance function of W-C.S.D is
completely canceled. At standard engine operation state, temperature of engine coolant becomes
over 56 degrees centigrade, and W-C.S.D never affects the exhaust emission.
Roller holder
W-C.S.D. piston W-C.S.D.
Expand
Engine
coolant
C.S.D. lever
Lever shaft
Pump side lever
Cold
Hot
Cancel
Retard Advance
010350-00E
8
7
6
5
4
3
2
1
0
-20-10 0 102030405060
Advance angle (crank degrees)
Temperature of coolant (degrees centigrade)
010351-00E
W-C.S.D of 4JH4-TE/4JH4-HTE