Engine JAC HFC4DA1-2C. Manual — part 8

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

31

g.

Measure the cam height of the camshaft. The standard
value is 42.02±0.05mm and the limit is 41.65mm. If
the measurement is out of the limit, make sure to
replace the camshaft.

h.

Use a multimeter to measure the outside diameter of
each camshaft journal. If any measurement is out of
the limit, replace the camshaft. The standard value for
outside diameter of journal is 49.945-49.975mm and
the limit is 49.60mm. If any measurement is out of the
limit, replace the camshaft.

i.

Use a feeler gauge to measure the axial run-out
clearance of the camshaft. The axial run-out clearance
of camshaft is 0.05~0.114mm.

j.

Use a multimeter to measure the outside diameter of
valve stem. If the measurement is less than the
specified limit, make sure to replace the valve and
valve guide in pair.

(Intake valve: 7.946-7.961mm; limit: 7.880mm)

(Exhaust valve: 7.921-7.936mm; limit: 7.850mm)

k.

Use a multimeter to measure the inside diameter of
valve guide and subtract the outside diameter of valve
stem from the measurement to obtain the valve guide
clearance. If the clearance obtained is out of specified
limit, make sure to replace the valve and valve guide in
pair.

(Limit of intake valve guide clearance: 0.200mm)

(Limit of exhaust valve guide clearance: 0.250mm)

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

32

l.

Measure the free height of valve spring. If the
measurement is out of specified limit, make sure to
replace the spring.

The standard value is 0.05mm or less and the limit is
0.20mm.

m. Use a feeler gauge to measure the clearance between

piston ring groove and piston ring.

If the clearance between piston ring groove and piston
ring is out of specified limit, make sure to replace the
piston.

n.

Use a feeler gauge to measure the opening gap of
piston ring.

If the opening gap of the piston ring is out of specified
limit, make sure to replace the piston.

o.

Install the steel-strip oil ring.

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

33

p.

Install the oil ring bush ring.

q.

Use a piston ring expander to install the 2

nd

compression ring and the 1

st

compression ring. While

installing the compression rings, face upward the
marking N (The lip of 2

nd

compression ring shall face

downward).

The overlap position of oil control ring cushion spring
and the opening of oil control ring steel strip shall be
180º away from each other and shall be 90º away from
the 2nd compression ring.

r.

Measure the outside diameter of main journal and the
inside diameter of main shaft bore.

Illustration of opening directions for

piston rings

Forward marking

Compression

ring

Overlap of oil

control ring

cushion spring

Opening of oil control
ring steel strip

Main thrust face

Auxiliary
thrust face

Compressi
on ring

Piston pin direction

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

34

s.

Measure the outside diameter of connecting rod journal
and the inside diameter of bush bore of connecting rod
fitted with bush.

Calculate the clearance between main journal of crankshaft
and the main bush bore of crankshaft: The difference
between the diameter of main journal and the inside
diameter of crankshaft main bush bore measured above is
the fitting clearance. The wear limit shall not exceed
0.11mm.

Notice: While measuring the inside diameter of
crankshaft main bush bore, install the bearing cap and
bush onto the bearing block and tighten the bolts to
specified torque. Use an inside multimeter to measure
the inside diameter.

Calculate the clearance between crankshaft connecting rod
journal and connecting rod bush bore: The difference
between the diameter of connecting rod journal and the
inside diameter of connecting rod bush bore measured
above is the fitting clearance. The wear limit shall not
exceed 0.10mm.