1993 DODGE TRUCK oil change

9
- 14
ENGINES
— — — •

SERVICE
DIAGNOSIS (DIESEL ENGINE)
•
MECHANICAL

CONDITION

r— ———
POSSIBLE
CAUSES
CORRECTION

LUBRICATING
OIL

PRESSURE
LOW Low oil
level.

(a)
Check
and
fill
with
clean engine oil.
(b) Check for a severe
external
oil leak
that
could reduce the pressure.
Oil viscosity thin,
diluted
or wrong specification.
Verify
the correct oil is being
used.
Check for oil dilution. Refer
to Contaminated Lube Oil (Engine Diagnosis—Mechanical).
Improperly operating pressure

switch/gauge.
Verify
the pressure switch is functioning correctly. If not,
replace switch/gauge.
Relief valve stuck open. Check/replace valve.

Plugged
oil
filter.
Change
oil
filter.
Oil
filter
change
interval
may need to be
revised.
If cooler was replaced, shipping

plugs
left
in cooler. Check/remove shipping
plugs.

If pump replaced, four cylinder
oil pump installed in a six
cylinder engine.
Verify
that
the correct pump is installed. If not, install an oil
pump for a six cylinder engine.

Loose
or
missing
cup
plugs.
Check and replace cup
plugs.

Worn oil pump. Check and replace oil pump.

Suction
tube
loose or seal leaking. Check and replace seal.

Loose
main bearing cap. Check and
install
new bearings and tighten cap to proper torque.
Worn bearings or wrong bearings installed. inspect and replace connecting rod or main bearings. Check and
replace piston cooling nozzles.

J9109-237

•
• —
ENGINES
9 - 15
CONDITION

POSSIBLE CAUSES
CORRECTION

LUBRICATING
OIL

PRESSURE
TOO
HIGH
Pressure
switch/gauge
not

operating
properly.
Verify
the
pressure
switch
is
functioning
correctly.
If not,

replace
switch/gauge.

Engine
running
too
cold.
Refer
to
Coolant
Temperature
Below
Normal
(Engine
Diagnosis-

Performance)

Oil
viscosity
too thick. Make
sure
the
correct
oil Is
being
used.
Refer
to
Group
O,

Lubrication
and
Maintenance.

Oil
pressure
regulator
valve

stuck
closed
or
binding.
Check
and replace valve, and/or oil cooler cover.

LUBRICATING
OIL
LOSS
External
leaks.
Visually
inspect for oil
leaks.
Repair as required.

Crankcase
being
overfilled. Verify that the correct dipstick is being
used.

incorrect
oil specification or

viscosity.
(a) Make sure the correct oil is being
used.

(b)
Look
for reduced
viscosity
from dilution with fuel.
(c) Review/reduce the oil
change
intervals.
Oil
cooler
leak.
Check
and replace the oil cooler.

High
blow-by
forcing oil out
the breather.
Check
the breather tube area for
signs
of oil
loss.
Perform the
required repairs.

Turbocharger
leaking
oil to the
air intake.
Inspect
the air
ducts
for evidence of oil transfer.

Repair
as required.

Worn
valve
seals.
Inspect
and replace the valve
seals.

Piston
rings
not
sealing
(oil

being
consumed
by the
engine).
Perform
blow-by check. Repair as required.

COMPRESSION
KNOCKS
Air in the
fuel
system.

Poor
quality
fuel.
Bleed
the fuel
system
(refer
to
Group
14, Fuel
System).

Verify by operating from a temporary tank with
good
fuel. Clean

and
flush the fuel
supply
tanks.
Replace fuel/water separator

filter.

Engine
overloaded. Verify that engine load rating is not being exceeded.
Incorrect injection
pump
timing.
Check
and time injection pump
(refer
to
Group
14, Fuel
System).

Improperly
operating
injectors.
Check
and replace inoperative injectors. J9109-266 SERVICE DIAGNOSIS (DIESEL ENGINE) - MECHANICAL (CONT.)

9
- 28 3.9L
ENGINE
•
accompanied by excessive clearance between the
valve stem and rocker arm as valve closes. In either
case,
tappet assembly should be removed for inspec­
tion and cleaning.
The valve train generates a noise very much like a
light tappet noise during normal operation. Care
must be taken to ensure that tappets are making the
noise. In general, if more than one tappet seems to
be noisy, its probably not the tappets.

REMOVAL
(1) Remove the air cleaner.
(2) Remove cylinder head cover.
(3) Remove rocker assembly and push rods. Iden­
tify push rods to ensure installation in original loca­
tion.
(4) Remove intake manifold.
(5) Remove yoke retainer and aligning yokes.
(6) Slide Hydraulic Tappet Remover/Installer Tool

C-4129-A
through opening in cylinder head and seat
tool firmly in the head of tappet.
(7) Pull tappet out of bore with a twisting motion.
If all tappets are to be removed, identify tappets to
ensure installation in original location. (8) If the tappet or bore in cylinder block is scored,
scuffed, or shows signs of sticking, ream the bore to
next oversize. Replace with oversize tappet.

CAUTION:
The
plunger
and
tappet bodies
are not

interchangeable.
The
plunger
and
valve must
al­

ways
be fitted to the
original body.
It is
advisable
to

work
on one
tappet
at a
time
to
avoid mixing
of
parts.
Mixed parts
are not
compatible.
DO NOT
dis­

assemble
a
tappet
on a
dirty
work bench.

DISASSEMBLE (1) Pry out plunger retainer spring clip (Fig. 17).
(2) Clean varnish deposits from inside of tappet
body above plunger cap.
(3) Invert tappet body and remove plunger cap,
plunger, check valve, check valve spring, check valve retainer and plunger spring (Fig. 17). Check valve
could be flat or ball.
ASSEMBLE (1) Clean all tappet parts in a solvent that will re­
move all varnish and carbon.
(2) Replace tappets that are unfit for further ser­
vice with new assemblies. (3) If plunger shows signs of scoring or wear, in­
stall a new tappet assembly. If valve is pitted, or
valve seat on end of plunger is prevented from seat­ ing, install a new tappet assembly.
(4) Assemble tappets (Fig. 17).

INSTALLATION
(1) Lubricate tappets.
PLUNGER
SPRING CHECK
BALL PLUNGER
RETAINER
SPRING CLIP
ROLLER

TAPPET
BODY RETAINER
I
PLUNGER
CHECK VALVE
SPRING PLUNGER
CAP
J9109-220
Fig.
17 Hydraulic
Tappet
Assembly

(2) Install tappets and push rods in their original
positions. Ensure that the oil feed hole in the side of
the tappet body faces up (away from the crankshaft).
(3) Install aligning yokes with ARROW toward
camshaft.
(4) Install yoke retainer. Tighten the bolts to 23
N*m (200 in. lbs.) torque. Install intake manifold.
(5) Install push rods in original positions. (6) Install rocker arms.
(7) Install cylinder head cover.
(8) Start and operate engine. Warm up to normal
operating temperature.

CAUTION:
To
prevent damage
to
valve mechanism,
engine must
not be run
above fast idle
until
all hy­
draulic tappets have
filled
with
oil and
have become
quiet.

VALVE
TIMING
(1) Turn crankshaft until the No.6 exhaust valve
is closing and No.6 intake valve is opening. (2) Insert a 6.350 mm (1/4 inch) spacer between
rocker arm pad and stem tip of No.l intake valve.
Allow spring load to bleed tappet down giving in ef­ fect a solid tappet. (3) Install a dial indicator so plunger contacts
valve spring retainer as nearly perpendicular as pos­ sible. Zero the indicator. (4) Rotate the crankshaft clockwise (normal run­
ning direction) until the valve has lifted 0.254 mm (0.010 inch). The timing of the crankshaft should
now read from 10° before top dead center to 2° after
top dead center. Remove spacer.

CAUTION:
DO NOT
turn
crankshaft
any
further

clockwise
as
valve spring might bottom
and
result in serious damage.

(5) If reading is not within specified limits: (a) Check sprocket index marks.
(b) Inspect timing chain for wear. (c) Check accuracy of DC mark on timing indica­
tor.

9
- 32 3.9L
ENGINE

•

Fig,
10 timing
Chain
Oil Tab installation
Fig,
11 Camshaft Bearings Removal and Installation

with
Tool
C-3132-A

Tool C-3132-A) at back of each bearing shell. Drive out bearing shells (Fig. 11).

INSTALLA
TION— BEARING (1) Install new camshaft bearings with Camshaft
Bearing Remover/Installer Tool C-3132-A by sliding
the new camshaft bearing shell over proper adapter.
(2) Position rear bearing in the tool. Install horse­
shoe lock and by reversing removal procedure, care­
fully drive bearing shell into place.
(3) Install remaining bearings in the same man­
ner. Bearings must be carefully aligned to bring oil
holes into full register with oil passages from the main bearing. If the camshaft bearing shell oil holes
are not in exact alignment, remove and install them
correctly. Install a new core hole plug at the rear of
camshaft. Be sure this plug does not leak. INSTALLATION
(1) Lubricate camshaft lobes and camshaft bearing
journals and insert the camshaft to within 51 mm (2 inches) of its final position in cylinder block.
Whenever an engine has been rebuilt, a new
camshaft and/or new tappets installed, add 1
pint of Mopar Crankcase Conditioner, or equiv­ alent. The oil mixture should be left in engine
for a minimum of 805 km (500 miles). Drain at
the next normal oil change.
(2) Install Camshaft Gear Installer Tool C-3509
with tongue back of distributor drive gear (Fig. 12).

Fig.
12 Camshaft
Holding
Tool C-3509 (Installed
Position)

(3) Hold tool in position with a distributor lock-
plate bolt. This tool will restrict camshaft from being
pushed in too far and prevent knocking out the welch
plug in rear of cylinder block. Tool should remain
installed until the camshaft and crankshaft sprockets and timing chain have been installed.
(4) Install camshaft thrust plate and chain oil tab.
Make sure tang enters lower right hole in thrust plate. Tighten bolts to 24 N*m (210 in. lbs.) torque.
Top edge of tab should be flat against thrust plate in order to catch oil for chain lubrication.
(5) Place both camshaft sprocket and crankshaft
sprocket on the bench with timing marks on exact
imaginary center line through both camshaft and
crankshaft bores.
(6) Place timing chain around both sprockets.

(7)
Turn crankshaft and camshaft to line up with
keyway location in crankshaft sprocket and in cam­ shaft sprocket.
(8) Lift sprockets and chain (keep sprockets tight
against the chain in position as described).
(9) Slide both sprockets evenly over their respec­
tive shafts and use a straightedge to check alignment of timing marks (Fig. 13).
(10) Install the camshaft bolt/cup washer. Tighten
bolt to 68 N*m (50 ft. lbs.) torque.
(11) Measure camshaft end play. Refer to Specifi­
cations for proper clearance. If not within limits in­ stall a new thrust plate.

9
- 38 3.9L
ENGINE

•

OIL
RING

SPACER
GAP

TOP

COMPRESSION
RING
GAP
SECOND

COMPRESSION

RING
GAP

OIL
RING
RAiL
GAP (TOP) OIL
RING
RAIL

GAP
(BOTTOM)
J9309-80

Fig.
14 Proper
Ring
Installation

CONNECTING ROD BEARINGS Fit all rods on a bank until completed. DO NOT al­
ternate from one bank to another, because connect­ ing rods and pistons are not interchangeable from
one bank to another.
The bearing caps are not interchangeable and
should be marked at removal to ensure correct as­ sembly.
Each bearing cap has a small V-groove across the
parting face. When installing the lower bearing shell, make certain that the V-groove in the shell is
in line with the V-groove in the cap. This provides
lubrication of the cylinder wall in the opposite bank.
The bearing shells must be installed so that the
tangs are in the machined grooves in the rods and
caps.
Limits of taper or out-of-round on any crankshaft
journals should be held to 0.025 mm (0.001 inch). Bearings are available in 0.025 mm (0.001 inch), 0.051 mm (0.002 inch), 0.076 mm (0.003 inch), 0.254
mm (0.010 inch) and 0.305 mm (0.012 inch) under-

size.
Install the bearings in pairs. DO NOT use a
new bearing half with an old bearing
half.
DO
NOT file the rods or bearing caps.
INSTALLATION (1) Be sure that compression ring gaps are stag­
gered so that neither is in-line with oil ring rail gap. (2) Before installing the ring compressor, make
sure the oil ring expander ends are butted and the
rail gaps located properly (Fig. 14).
(3) Immerse the piston head and rings in clean en­
gine oil. Slide Piston Ring Compressor Tool C-385
over the piston and tighten with the special wrench (part of Tool C-385). Be sure position of rings does
not change during this operation.
(4) Install connecting rod bolt protectors on rod

bolts,
the long protector should be installed on the numbered side of the connecting rod. (5) Rotate crankshaft so that the connecting rod
journal is on the center of the cylinder bore. Be sure connecting rod and cylinder bore number are the
same. Insert rod and piston into cylinder bore and
guide rod over the crankshaft journal.
(6) Tap the piston down in cylinder bore, using a
hammer handle. At the same time, guide connecting
rod into position on crankshaft journal.
(7) The notch or groove on top of piston must be
pointing toward front of engine. The larger chamfer
of the connecting rod bore must be installed toward
crankshaft journal fillet.
(8) Install rod caps. Be sure connecting rod, con­
necting rod cap and cylinder bore number are the same. Install nuts on cleaned and oiled rod bolts and
tighten nuts to 61 N»m (45 ft. lbs.) torque.
(9) Install the oil pan. (10) Install the cylinder head.
(11) Install the engine into the vehicle.

CRANKSHAFT
A crankshaft which has undersize journals will be
stamped with 1/4 inch letters near the notch of the
No.6 crankshaft counterweight (Fig. 15). FOR EXAMPLE:R2 stamped on the No.6 crank­
shaft counterweight indicates that the No.2 rod jour­
nal is 0.025 mm (0.001 in) undersize. M4 indicates
that the No.4 main journal is 0.025 mm (0.001 in) undersize. R3 M2 indicates that the No.3 rod journal
and the No.2 main journal are 0.025 mm (0.001 in) undersize.

Undersize
Journal Identification
Stamp

ROD
-
0.025mm
(0.001
in.)
Rl-R2-R3-Etc.

MAIN -
0.025mm
(0.001
in.)
M1-M2-M3
or M4

STEEL
STAMP
IDENTIFICATION

R
(ROD)
AND/OR
M
(MAIN)
FOLLOWED
BY THE ROD
OR
MAIN
NUMBER

Fig.
15 Location of Crankshaft
Identification

When a crankshaft is replaced, all main and con­
necting rod bearings should be replaced with new
bearings. Therefore, selective fitting of the bearings is not required when a crankshaft and bearings are
replaced.
REMOVAL (1) Remove the oil pan.

•
3.9L
ENGINE
9 - 39 (2) Remove the oil pump from the rear main bear­
ing cap.
(8)
Identify bearing caps before removal. Remove
bearing caps and bearings one at a time.
(4) Lift the crankshaft out of the block.
(5) Remove and discard the crankshaft rear oil

seals.

(6)
Remove and discard the front crankshaft oil
seal.
INSPECTION OF JOURNALS The crankshaft connecting rod and main journals
should be checked for excessive wear, taper and scor­
ing. The maximum taper or out-of-round on any
crankshaft journal is 0.025 mm (0.001 inch).
Journal grinding should not exceed 0.305 mm
(0.012 inch) under the standard journal diameter. DO
NOT grind thrust faces of No.3 main bearing. DO
NOT nick crank pin or bearing fillets. After grind­
ing, remove rough edges from crankshaft oil holes and clean out all oil passages.

CAUTION:
After any journal
grind,
it is important

that
the
final
paper or cloth
polish
be in the
same
direction as the engine rotates.
INSTALLATION (1) Lightly oil the new upper seal lips with engine

oil.
(2) Install the new upper rear bearing oil seal with
the yellow paint facing towards the rear of the en­
gine.

(3) Position the crankshaft into the cylinder block.
(4) Lightly oil the new lower seal lips with engine

oil.
(5) Install the new lower rear bearing oil seal into
the bearing cap with the yellow paint facing towards the rear of the engine.
(6) Apply 5 mm (0.20 in) drop of Loctite 515, or
equivalent, on each side of the rear main bearing cap (Fig. 16). Do not over apply sealant or allow the seal­
ant to contact the rubber seal. Assemble bearing cap
to cylinder block immediately after sealant applica­ tion.
(7) To align the bearing cap, use cap slot, align­
ment dowel and cap bolts. Do not remove excess ma­
terial after assembly. Do not strike rear cap more
than 2 times for proper engagement.
(8) Clean and oil all cap bolts. Install all main
bearing caps. Install all cap bolts and alternately
tighten to 115 N»m (85 ft. lbs.) torque.

(9)
Install oil pump.
(10) Apply Mopar Silicone Rubber Adhesive Seal­
ant, or equivalent, at bearing cap to block joint to
provide cap to block and oil pan sealing (Fig. 17). Ap-
BEARING CAP
J9309-72

Fig.
16 Sealant Application to Bearing Cap ply enough sealant until a small amount is squeezed
out. Withdraw nozzle and wipe excess sealant off the
oil pan seal groove.
(11) Install new front crankshaft oil seal. (12) Immediately install the oil pan.

MOPAR SILICONE SEALANT

RUBBER
ADHESIVE APPLIED
Fig.
17
Apply
Sealant to Bearing Cap to
Block
Joint

CRANKSHAFT MAIN BEARINGS
Bearing caps are not interchangeable and should
be marked at removal to ensure correct assembly.
Upper and lower bearing halves are NOT inter­ changeable. Lower main bearing halves of No.l and
3 are interchangeable. Upper and lower No.2 bearing halves are flanged
to carry the crankshaft thrust loads. They are NOT interchangeable with any other bearing halves in the
engine (Fig. 18). Bearing shells are available in stan­
dard and the following undersizes: 0.25 mm (0.001

inch),
0.051 mm (0.002 inch), 0.076 mm (0.003 inch),
0.254 mm (0.010 inch) and 0.305 mm (0.012 inch).
Never install an undersize bearing that will reduce
clearance below specifications.
REMOVAL (1) Remove the oil pan.

CAUTION:
Th© plunger and
tappet
bodies are not
interchangeable. The plunger and valve must al­

ways
be
fitted
to the
original
body. It is advisable to

work
on one
tappet
at a
time
to avoid
mixing
of parts. Mixed
parts
are not
compatible.
DO NOT
dis­

assemble
a
tappet
on a
dirty
work
bench,

DISASSEMBLE
(1) Pry out plunger retainer spring clip (Fig. 17).
(2) Clean varnish deposits from inside of tappet
body above plunger cap.
(3) Invert tappet body and remove plunger cap,
plunger, check valve, check valve spring, check valve
retainer and plunger spring (Fig. 17). Check valve could be flat or ball.

ASSEMBLE

(1) Clean all tappet parts in a solvent that will re­
move all varnish and carbon.
(2) Replace tappets that are unfit for further ser­
vice with new assemblies.
(3) If plunger shows signs of scoring or wear, in­
stall a new tappet assembly. If valve is pitted, or
valve seat on end of plunger is prevented from seat­
ing, install a new tappet assembly. (4) Assemble tappets (Fig. 17).
PLUNGER
CHECK

BALL
PLUNGER
RETAINER
SPRING CLIP
ROLLER
TAPPET BODY RETAINER I PLUNGER
CHECK VALVE
SPRING PLUNGER
CAP
J9109-220
Fig.
17 Hydraulic
Tappet
Assembly

INSTALLATION
(1) Lubricate tappets.
(2) Install tappets and push rods in their original
positions. Ensure that the oil feed hole in the side of
the tappet body faces up (away from the crankshaft). (3) Install aligning yokes with ARROW toward
camshaft. (4) Install yoke retainer. Tighten the bolts to 23
N»m (200 in. lbs.) torque. Install intake manifold. (5) Install push rods in original positions.
(6) Install rocker arm.
(7) Install cylinder head cover.
(8) Start and operate engine. Warm up to normal
operating temperature.
CAUTION: To
prevent
damage to valve mechanism,
engine must not be run above
fast
idle
until
all hy­
draulic
tappets
have
filled
with
oil and have become
quiet.
VALVE
TIMING

(1) Turn crankshaft until the No.6 exhaust valve
is closing and No.6 intake valve is opening. (2) Insert a 6.350 mm (1/4 inch) spacer between
rocker arm pad and stem tip of No.l intake valve. Allow spring load to bleed tappet down giving in ef­
fect a solid tappet. (3) Install a dial indicator so plunger contacts
valve spring retainer as nearly perpendicular as pos­
sible.
Zero the indicator. (4) Rotate the crankshaft clockwise (normal run­
ning direction) until the valve has lifted 0.254 mm (0.010 inch). The timing of the crankshaft should
now read from 10° before top dead center to 2° after
top dead center. Remove spacer.

CAUTION:
DO NOT
turn
crankshaft any
further

clockwise as valve spring
might
bottom
and
result
in serious
damage.

(5) If reading is not within specified limits: (a) Check sprocket index marks.
(b) Inspect timing chain for wear.
(c) Check accuracy of DC mark on timing indica­
tor.

VIBRATION DAMPER
REMOVAL (1) Disconnect the negative cable from the battery.
(2) Remove fan shroud retainer bolts and set
shroud back over engine.
(3) Remove the cooling system fan.
(4) Remove the serpentine belt (refer to Group 7,
Cooling System).
(5) Remove the vibration damper pulley. (6) Remove vibration damper bolt and washer from
end of crankshaft. (7) Install bar and screw from Puller Tool Set
C-3688. Install 2 bolts with washers through the
puller tool and into the vibration damper (Fig. 1).
(8) Pull vibration damper off of the crankshaft.
J9209-81

Fig.
1
Vibration
Damper
Assembly

9 - 62 5.2L
ENGINE
Fig,
11 Camshaft
Bearings
Removal
and
installation

with
Tool C-3132-A
Tool C-3132-A) at back of each bearing shell. Drive out bearing shells (Fig. 11).

INSTALL A
TION-
BEARING
(1) Install new camshaft bearings with Camshaft
Bearing Remover/Installer Tool C-3132-A by sliding
the new camshaft bearing shell over proper adapter. (2) Position rear bearing in the tool. Install horse­
shoe lock and by reversing removal procedure, care­
fully drive bearing shell into place. (3) Install remaining bearings in the same man­
ner. Bearings must be carefully aligned to bring oil
holes into full register with oil passages from the
main bearing. If the camshaft bearing shell oil holes are not in exact alignment, remove and install them
correctly. Install a new core hole plug at the rear of
camshaft. Be sure this plug does not leak.

INSTALLATION
(1) Lubricate camshaft lobes and camshaft bearing
journals and insert the camshaft to within 51 mm (2 inches) of its final position in cylinder block.
Whenever an engine has been rebuilt, a new
camshaft and/or new tappets installed, add 1
pint of Mopar Crankcase Conditioner, or equiv­ alent. The oil mixture should be left in engine
for a minimum of 805 km (500 miles). Drain at
the next normal oil change.
(2) Install Camshaft Gear Installer Tool C-3509
with tongue back of distributor drive gear (Fig. 12).
Fig.
12 Camshaft
Holding
Tool C-3509 (Installed

Position)
• — —— — — •

Fig.
13
Alignment
of Timing Marks
(10) Install the camshaft bolt/cup washer. Tighten
bolt to 68 N«m (50 ft. lbs.) torque. (11) Measure camshaft end play. Refer to Specifi­
cations for proper clearance. If not within limits in­ stall a new thrust plate.
(12) Each tappet reused must be installed in the
same position from which it was removed. When
camshaft is replaced, all of the tappets must be
replaced.

DISTRIBUTOR
REMOVAL
Refer to Group 8D, Ignition Systems for the proper
procedure.

REMOVAL-DRIVE SHAFT BUSHING
(1) Insert Distributor Drive Shaft Bushing Puller
Tool C-3052 into old bushing and thread down until a tight fit is obtained (Fig. 14). (3) Hold tool in position with a distributor lock-
plate bolt. This tool will restrict camshaft from being
pushed in too far and prevent knocking out the welch
plug in rear of cylinder block Tool should remain installed until the camshaft and crankshaft sprockets and timing chain have been installed.

(4)
Install camshaft thrust plate and chain oil tab.
Make sure tang enters lower right hole in thrust plate. Tighten bolts to 24 N*m (210 in. lbs.) torque.
Top edge of tab should be flat against thrust plate in
order to catch oil for chain lubrication.
(5) Place both camshaft sprocket and crankshaft
sprocket on the bench with timing marks on exact
imaginary center line through both camshaft and crankshaft bores.
(6) Place timing chain around both sprockets. (7) Turn crankshaft and camshaft to line up with
keyway location in crankshaft sprocket and in camshaft sprocket.
(8) Lift sprockets and chain (keep sprockets tight
against the chain in position as described). (9) Slide both sprockets evenly over their respec­
tive shafts and use a straightedge to check alignment of timing marks (Fig. 13).