MCi Crusader II 1989 Maintenance Manual page 140

Date
1-1-89 Page
4-10
MC-9 MAINTENANCE MANUAL
INSPECTION
1. Check fit of
wrist
pins on pistons and connecting rod
bushings. Wrist pin should be a light press fit in pistons. If
wrist
pin is a loose fit. the pin, piston, or both should be replaced.
2. Check fit of
wrist
pin in connecting rod bushing by rocking
the piston. This clearance should not exceed .0007" (.0178
mm). Replace wrist pin bushing if excess clearance is found.
Wrist pin bushings should be reamed after being pressed into
connecting rods. Replace used wrist pin lockwires.
3. Always replace die cast aluminum rods with new ones.
4. Check fit of piston rings in piston ring grooves. Check ring
gap with rings installed in cylinder bores. Refer to figure 4-11
for correct gap aRd groove clearance.
5. Check crankshaft screw threads, keyways, tapered ends
and all machined and ground surfaces for wear. scores. or
damage. Crankshaft journals which are out of round more than
.001" (.0254 mm) must be reground. Bearing inserts are avail-
able in .010" (.254 mm), .020" (.508 mm) and .030'' (.762 mm)
undersizes for reground crankshafts. Main bearing journals
must be maintained so bearings are snug fit
6. The oil seal ring groove or grooves in crankshafts fitted
with oil rings must not be worn.
NOTE: The ring groove walls must have a
good finish ~nd they must be square. Check
to be sure the oil passages are open and
clean through the crankshaft.
7 Check connecting rod bearings on crankshaft journals for
proper fit. Used bearing inserts should be replaced. Connecting
rod caps are not interchangeable. The locking slots of the _
connecting rod and cap should be positioned adjacent to each
other.
8. Check clearance between the connecting rod journal and
the connecting rod bearing. It must not be less than .0003"
{.0076 mm) or more than .0021" (.0533 mm) after rebuilding.
9. Check for wear or flat spots. If found, bearings should be
replaced. If type with sleeve bearing, this bearing should be
checked for scores and wear and replaced if necessary.
REPAIRS
DISCHARGE VALVES AND SEATS:
1. If discharge valve seats merely show signs of slight wear.
they can be dressed by using a lapping stone, grinding com-
pound and grinding toot. Install new discharge vaives. valve
springs, and cap nuts. The discharge valve travel should be
between .030-.046" (.762-1.168 mm).
2. To test for leakage past the discharge valves, apply about
100 psi (690 kPa> air pressure through the cylinder head dis-
charge port and apply soap suds at the discharge valves and
seats. If excessive leakage is found. leave the air pressure
applied. and with the use of a fiber or hardwood dowel and
hammer, tap the discharge valves off their seats several times.
This will help the valves to seat and should reduce any leakage.
3. With air pressure still applied at the discharge port of the
cylinder head, check for leakage at the discharge valve cap-
nuts. No leakage is permissible.
INLET VALVES ANO SEATS:
4. If inlet valve seats show signs of slight nicks or scratches,
they can be redressed with a fine piece of emery cloth or by
lapping with a lapping stone, grinding compound and grinding
tool. If the seats are damaged to the extent that they cannot be
reclaimed. they should be replaced. The dimension from the top
of the cylinder block to the inlet valve seat should not exceed
.145" (3.683 mm) nor be less than .101" (2.565 mm). Slightly
worn or scratched inlet valves can be reclaimed by lapping
them on a piece of fine crocus cloth on a flat surface, but it is
suggested that new inlet valves be installed.
REASSEMBLY
1. Position block gasket and block on crankcase according
to markings made prior to disassembly. Using capscrews with
lockwashers. secure cylinder block to crankcase.
2. If the crankshaft is fitted with oil seal rings, install rings.
Position ball bearings and crankshaft in crankcase making
sure the drive end of the crankshaft is positioned as marked
before disassembly.
3. Carefully press crankshaft and bearings into crankcase
using arbor press.
4. Position a new rear end cover gasket over the rear end of
the crankcase making sure the oil hole in the gasket lines up
with the oil hole in the crankcase.
5. Position end cover with oil seal ring installed over crank-
case and end cover gasket. The end cover should be positi-
oned correctly in relation to the oil holes in the gasket and
crankcase. Secure the end cover to the crankcase with cap-
screws and lockwashers.
6. If the opposite end cover requires an oil seal (removed on
disassembly), a new seal should be pressed into end cover.
Position new end cover gasket and carefully install end cover
over c_rankshaft and to crankcase avoiding damage to the seal.
Secure end cover with capscrew and lockwashers. If connect-
ing rods are steel, they can be reused and serviced as follows.
Do not reuse aluminum die cast connecting rods.
7. If new wrist pin bushings are to be used. they_should be
pressed into the connecting rods so that the oil hole in the
bushing lines up with the one in the rod. The new bushings
should then be reamed or honed to provide between .0001"
(.0025 mm) and .0006" (.0152 mm) clearance on the wrist pin.
8. Position connecting rod in piston and press in wrist pin so
that lockwire hole in the pin aligns with that in the piston.
9. Install
new lockwire
through piston and
wrist
pin and lock
it by snapping short end into
lockwire
hole at the bottom of the
piston.
. 10. Install piston rings in correct location with ring pipmarks
up. Stagger the position of the ring gaps.
11. Coat piston. piston rings,
wrist
pin and connecting rod
bearings with clean engine oil before installing them in the
compressor.
12. Remove connecting rod bolts and bearing cap from one
connecting rod.
CAUTION: It is important that caps and
rods are not intermixed.
13. Turn crankshaft so one of its connecting rod journals is
in the downward, center position. Insert the connecting rod with
piston through the top of the cylinder whose journal is down.
14. Position and attach the bearing cap to the connecting
rod making sure the bolt and lockwashers are properly posi-
tioned on the cap. Tighten connecting rod bolts evenly and
bend the two new lockwasher prongs up against the hex head
of the bolt