Page 145 of 2189
Rocker Arms and Lost Motion Assemblies
Inspection (D16Y5, Dt6Y8 enginesl
NOTEr When reassembling the primary rocker arm,carefully apply air pressure to the oil passage of therocker arm.
1. Inspect the rocker arm piston. push it manually.- lf it does not move smoothly, replace the rockerarm assembty.
Dl6Y5 engine:
ROCKER ARM
TIMING PISTON
TIMING SPRING
SYNCHRONTZINGPISTON
SECONDARYROCKER ARM
MID ROCKER ARM
PRIMARY ROCKER
SYNCHRONIZINGPISTON A
NOTE:
. Apply oil to the pistons when reassembling.o Bundle the rocker arms with a rubber band to preventthem from separating.
6-34
(\
DI6YS engine:
NOTE: Set the timing plate and return spring as shownoerow.
RETURN
CAMSHAFT HOLDER
Dl6Yg engine:
2. Remove the lost motion assembly from the holderand inspect it. Test it by pushing the plunger withyour finger.- lf the lost motion assembly plunger does notmove smoothly, replace it.
LOST MOTION ASSEMBLY
\a
Pu3h
I
Page 146 of 2189
Rocker Arms and Shafts
Clearance Inspection
Measure both the intake rocker shaft and exhaust rocker
shaft.
1. Measure the diameter of the shaft at the first rocker
locatron.
2. Zero the gauge to the shaft diameter'
I
3. Measure the inside diameter of the rocker arm and
check for an out of-round condition.
Rockel Arm-to-Shaft Clearance
Standard (Newl:
lntake: 0.017 - 0.050 mm
{0.0007 - 0.0020 inl
Exhaust: 0.018 - 0.054 mm
(0 0007 - 0 0021 in)
Service Limit:0.08 mm {0.003 inl
Repeat these measurements on all the rockers.
- lf the clearance is over the service limit, replace the
rocker shaft and all over tolerance rocker arms.
6-35
Page 147 of 2189

Gamshaft
Inspection
NOTE:
. Do not rotate the camshaft during inspection.. Remove the rocker arms and rocker shafts.
1. Put the camshaft and the camshaft holders on thecylinder head. then tighten the bolts to the specified
toroue.
Spocified torqu€:
8 mm bolts; 20 N.m (2.0 kgf.m t4 lbf.ft)Apply engin6 oil to tho throads,
6 mm bohs: t2 N.m (1.2 kgf'm 8.7 tbf.ft)
Apply oogine oil to the thleads.
6 mm bolts: @, @ @, @
6-36
E
\(
2. Seat the camshaft by pushing it toward the rear ofthe cylinder head.
3, Zero the dial indicator against the end ofthe camshaft.Push the camshaft back and fonh, and read the endptav.
Camshaft End Play:
Standard {New):0.05 - 0.15 mm
10.002 - 0.006 inl
Sorvice Limit 0.5 mm (0.02 in,
I
5.
Remove the bolts, then remove the camshaft hold-ers from the cylinder head.- Lift the camshaft out of the cylinder head, wipe itclean, then inspect the liit ramps, Replace thecamshaft if any lobes are pitted. scored, orexcessively worn,- Clean the camshaft bearing surfaces in the cylin-der head, then set the camshaft back in place.- Place a plastigage strip across each Iournal.
Install the camshaft holders, and tighten the bolts tothe soecified toroue.
\,l
Page 148 of 2189

6, Remove the camshaft holders. then measure the
widest ponion of the plastigage on each journal.
Camshaft-to-Holder Oil Clearance:
Standard lNew):0.050 - 0.08!t mm
{0.002 - 0.004 in}
Service Limit : 0.15 mm {0.006 in)
lf the camshaft-to-holder oil clearance is out ot tol-
erance:- And the camshaft has already been replaced,
you must replace the cylinder head.
- lf the camshaft has not been replaced, first check
the total runout with the camshaft supported on
V-blocks.
Camshaft Total Runout:
Standard (New): 0.03 mm (0.001 inl max.
Service Limit: 0.04 mm {0.(X)2 in)
-7.
Rotate camshattwhile measuring.
L
- lf the total runout of the camshaft is within toler-
ance, replace the cylinder head.
- lf the total runout is out of tolerance, replace the
camshaft and recheck the camshaft-to-holder oil
clearance. lf the oil clearance is still out of toler-
ance. replace the cylinder head.
INTAKEEXHAUST
O16Y/ engine35.299 (1.3897)37.281 (1.4678)
D16Y5
engrne
PRI38.427 11.5129138.784 (1.5269)
SEC32.193 (1.2674)
D l6Y8
engrne
PRI36.77811.44791
38.008 (1.4964)MID38.274 (1.5068)
sEu37.065 (1.4592)
8. Check the cam lobe height wear.
Cam lobe height standard (New)
t/g a* rN Ex
- D16Y5 engine
PRI; Primary cam lobe, SEC: Secondary cam lobe
MtD: Mid cam lobe. T/B: Timing belt
lN: Intake, EX: Exhaust
PRIsEcMIDSEC
rts
- Dl6YE ongine
Unit mm (in)
Check this area {or wear.
6-37
Page 150 of 2189

Valve Guides
lntake Valve Dimensions
A Standsrd lNewl: 29.9 - 30.1 mm
B Standard (New):
C Standald {Newl:
C Service Limit:
D Standard (New):
D Service Limit:
11.18 - 1.19 inl
117.42 - 117.72 mm
(4.523 - 4.635 inl
5.'18 - 5.49 mm
{0.2r57 - 0.2r61 in)
5.,[5 mm (0.21,16 in]
0.85 - 1.15 mm
(0.033 - 0.0'15 in)
0.65 mm (0.026 in)
Exhaust Valve Dimensions
A Standard lNew): 25.9 - 26.1 mm
B Standard {Newl:
C Standard {New):
C Service Limit:
D Standard {New):
D Service Limit:
(1.02 - 1.03 in)
114.60 - 114.90 mm
11.512 - 4.521in1
5.i[5 - 5.46 mm
10.21lt6 - 0.2150 inl
5.,12 mm 10.213'l in)
1.05 - 1.35 mm
{0.041 - 0.053 in)
0.95 mm {0.037 in}
Valve Movement
Measure the guide-to-stem clearance with a dial indi-
cator while rocking the stem in the direction of normal
thrust (wobble method).
lniake Valve Stem-to-Guide Clearance:
St8ndard lNew): 0.04 - 0.10 mm
10.002 - 0.004 in)
Service Limit: 0.16 mm 10.006 in)
Exhaust Valvs Stem-to-Guide Glearance:
Standard {New}: 0.10 - 0.16 mm
10.004 - 0.006 in)
Sorvice Limit 0.22 mm (0.009 in)
O/'-_)
. lf the measurement exceeds the service limit,
recheck using a new valve.
. lf the measurement is now within the service
limit, reassemble using a new valve.
. lf the measurement still exceeds the limit,
recheck using the alternate method below, then
replace the valve and guide, if necessary.
NOTE: An alternate method of checking guide to
stem clearance is to subtract the O.D. of the valve
stem, measured with a micrometer, from the l.D. of
the valve guide, measured with an inside
micrometer or ball gauge. Take the measurements
in three places along the valve stem and three
places inside the valve guide. The difference be-
tween the largest guide measurement and the
smallest stem measurement should not exceed the
service limit.
lntake Valve Stgm-to-Guidg clearance:
Standard {Newl: 0.02 - 0.05 mm
{0.001 - 0.002 in)
Ssrvico Limit 0.08 mm (0.003 in)
Exhaust Valvo Stem-to-Guide Clearance:
Standard {New): 0.05 - 0.OB mm
{0.002 - 0.003 in)
S€rvice Limit 0.11 mm (o'Ooil in)
Valve extended 10 mm out from seat.
6-39
Page 151 of 2189

Cylinder HeadValve Seats
Warpage
NOTE: lf the camshaft-to-holder oil clearances (see
page 6-36) are not within specification, the cylinder head
cannot be resurfaced.
lf the camshaft-to-holder oil clearances are within sDeci,
fications, check the cylinder head lor warpage.
lf warpage is less than 0.05 mm (0.002 in), cylin-
der head resurfacing is not required.
lf warpage is between 0.05 mm (0.002 in) and
0.2 mm {0.008 in), resurface the cylinder head.
Maximum resurface limit is 0,2 mm (0.008 in)
based on a height of 93 mm (3.66 in).
Measure along edges, and three ways across center.
Cylinder Head Height:
Standard {Newl: 92.95 - 93.05 mm
{3.659 - 3.66:} in)
6-40
\
Reconditioning
'1. Renew the valve seats in the cylinder head using a
valve seat cutter.
NOTE: lf the guides are worn (see page 6-39).
replace them (see page 6-41) belore cutting the
valve seats.
VALVE SEATCUTTER(Commercially available)
2.
?
4.
Carefully cut a 45'seat, removing only enough
material to ensure a smooth and concentric seat.
Bevel the upper edge of the seat with the 30. cutter
and the lower edge of the seat with the 60' cutter.
Check the width of the seat and adjust accordingly.
Make one more very light pass with the 45" cutter to
remove any possible burrs caused by the other cut-
Iers.
Valve Seat Width:
Standard (N€w):
Intake: 0.85 - 1.15 mm 10.033 - 0.045 in)
Exhaust: 1.25 - 1.55 mm {0.049 - 0.061 in}
Sorvice Limit:
Intake: 1.6 mm (0.063 inl
Exhausl: 2.0 mm (0.079 in)
Seat Width
5. After resurfacing the seat, inspect for even valve
seatingr Apply Prussian Blue compound to the
valve face, and insert the valve in its original loca-
tion in the head, then liit and snap it closed against
the seat several times.
Page 152 of 2189

Valve Guides
7.
VALVESEAT
PFUSSIAN BTUE COMPOUNO
The actual valve seating surface. as shown by the
blue comDound, should be centered on the seat.
. lf it is too high (closer to the valve stem), you
must make a second cut with the 60'cutter to
move it down, then one more cut with the 45'
cutter to restore seat width,
. lf it is too low (closer to the vslve edge), you
must make a second cut with the 30" cutter to
move it uD, then one more cut with the 45'cutter
to restore seat width.
NOTE: The final cut should always be made with
the 45" cutter.
lnsert the intake and exhaust valves in the head and
measure the valve stem installed height.
Intake. Exhau3t Siem Installsd Height:
Standard (New): 53.17 - 53.6,4 mm
12.093 - 2.112 in)
Sorvice Limit: 53.89 mm (2.122 in)
lf the valve stem installed height is over the service
limit. reDlace the valve and recheck. lf its still over
the service limit, replace the cylinder head; the
valve seat in the head is too deep.
VALVE STEMINSTALLED HEIGHT
8.
\-
Replacement
1.As illustrated below, use a commercially-available
air-impact valve guide driver attachment modified
to fit the diameter of the valve guides. In most cases.
the same procedure can be done using the special
tool and a conventional hammer.
VALVE GUIDE DRIVERlCommerciallv available)5.3 mm
87 mm +- 57 mft
t3.43 in) | 12 24 inl
tr-r'10.8 mm(0.42 inl
or
VALVE GUIDE DRIVER, 5.5 mm
07742 - 0010100
Select the proper replacement guides. and chill them
in the freezer section of a refrigerator for about an
nour.
Use a hot plate or oven to evenly heat the cylinder
head to 300"F (150'C). Monitor the temperature with
a cooking thermometer.
CAUTION:
. Do not use a torch; it may warp the head.
Do not got the head hottel than 300"F (150"C1;
excessive heat may loosen thg valve seats.
To avoid burns. use heayy gloves whon handling
the heated cylinder h€ad.
{cont'd)
6-41
Page 153 of 2189

Valve Guides
Replacement (cont'd)
Working from the camshaft side, use the driver andan air hammer to drive the guide about 2 mm (0.1 in)towards the combustion chamber. This will knock offsome of the carbon and make removal easier.
CAUTION:
. Always wear satety goggles or a face shield when
driving valve guides.
. Hold the air hammer directly in line with thevalve guide to prevent damaging the driver.
Turn the head over, and drive the guide out towardthe camshaft side of the head.
VALVE GUIOE ORIVER,5.5 mm07742 - 001 01 00
It a valve guide still won't move, drill it out with a8 mm {5/16 in) bit, then try again.
CAUTION: Drill guides only in extreme cases; you
could damage the cylinder head it the guide breaks.
6. Remove the new guides from the freezer, one at atime, as you need them.
6-42
I7. Apply a thin coat of clean engine oil to the outsideof the new valve guide. Install the guide from thecamshaft side of the head; use the special tool todrive the guide in to the specified insralled height. lfyou have all 16 guides to do, you may have to reheat
the head.
VALVE GUIOEDRIVER,5.5 mm07742 - 0010100
ll
Valve Guide lnstalled Height:
Intake: 17.85 - 18.35 mm (0.703 - 0.722 inl
Exhausi: 18.65 - 19.15 mm (0.734 - 0.754 in)
VALVE GUIDE