gas mileage MITSUBISHI DIAMANTE 1900 Repair Manual

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1-2 GENERALINFORMATIONAND MAINTENANCE
Chitton’s Total Car Care manual for the 199M10
Mitsubishi Mirage, Galant and Diamante is intended
to help you learn more about the inner workings of
your vehicle while saving you money on its upkeep
and operation.
The beginning of the book will likely be referred to
the most, since that is where you will find information
for maintenance and tune-up. The other sections deal
with the more complex systems of your vehicle. Oper-
ating systems from engine through brakes are cov-
ered to the extent that the average do-it-yourselfer be-
comes mechanically involved. This book will not
explain such things as rebuilding a differential for the
simple reason that the expertise required and the in-
vestment in special tools make this task uneconomi-
cal. It will, however, give you detailed instructions to
help you change your own brake pads and shoes, re-
place spark plugs, and perform many more jobs that
can save you money, give you personal satisfaction
and help you avoid expensive problems.
A secondary purpose of this book is a reference for
owners who want to understand their vehicle and/or
their mechanics better. In this case, no tools at all are
required.
Before removing any bolts, read through the entire
procedure. This will give you the overall view of what
tools and supplies will be required. There is nothing
more frustrating than having to walk to the bus stop
on Monday morning because you were short one bolt
on Sunday afternoon. So read ahead and plan ahead.
Each operation should be approached logically and
all procedures thoroughly understood before attempt-
ing any work.
All sections contain adjustments, maintenance, re-
moval and installation procedures, and in some cases,
repair or overhaul procedures. When repair is not con-
sidered practical, we tell you how to remove the part
and then how to install the new or rebuilt replacement.
In this way, you at least save labor costs. “Backyard”
repair of some components is just not practical.
Many procedures in this book require you to “label
and disconnect. . ” a group of lines, hoses or wires.
Don’t be lulled into thinking you can remember where
everything goes-you won’t. If you hook up vacuum
or fuel lines incorrectly, the vehicle may run poorly, if
at all. If you hook up electrical wiring incorrectly, you
may instantly learn a very expensive lesson.
You don’t need to know the official or engineering
name for each hose or line. A piece of masking tape
on the hose and a piece on its fitting will allow you to
assign your own label such as the letter A or a short name. As long as you remember your own code, the
lines can be reconnected by matching similar letters
or names. Do remember that tape will dissolve in
gasolrne or other fluids; if a component is to be
washed or cleaned, use another method of identifica-
tion. A permanent felt-tipped marker or a metal scribe
can be very handy for marking metal parts. Remove
any tape or paper labels after assembly.
It’s necessary to mention the difference between
maintenance and repair Maintenance includes rou-
tine inspections, adjustments, and replacement of
parts which show signs of normal wear Maintenance
compensates for wear or deterioration. Repair implies
that something has broken or is not working. A need
for repair is often caused by lack of maintenance. Ex-
ample, draining and refilling the automatic transaxle
fluid is maintenance recommended by the manufac-
turer at specific mileage intervals. Failure to do this
can shorten the life of the transmission/transaxle, re-
quiring very expensive repairs. While no maintenance
program can prevent items from breaking or wearing
out, a general rule can be stated: MAINTENANCE IS
CHEAPER THAN REPAIR.
Two basic mechanrc’s rules should be mentioned
here. First, whenever the left side of the vehicle or en-
gine is referred to, it is meant to specify the drivers
side. Conversely, the right side of the vehicle means
the passengers side. Second, screws and bolts are
removed by turning counterclockwise, and tightened
by turning clockwrse unless specifically noted.
Safety is always the most important rule. Con-
stantly be aware of the dangers involved in working
on an automobile and take the proper precautions.
See the informatron in this section regarding SER-
VICING YOUR VEHICLE SAFELY and the SAFETY
NOTICE on the acknowledgment page.
Pay attention to the instructions provided. There
are 3 common mistakes in mechanical work:
1. Incorrect order of assembly, disassembly or
adjustment. When taking something apart or putting
it together, performing steps in the wrong order usu-
ally just costs you extra time; however, it CAN break
something. Read the entire procedure before begin-
ning disassembly. Perform everything in the order in
which the instructions say you should, even if you
can’t immedrately see a reason for it. When you’re
taking apart something that is very intricate, you
might want to draw a picture of how it looks when as-
sembled at one point in order to make sure you get everything back in its proper position. We will supply
exploded views whenever possible. When making
adjustments, perform them in the proper order. One
adjustment possibly will affect another.
2. Overtorquing (or undertorquing). While it is
more common for overtorquing to cause damage,
undertorquing may allow a fastener to vibrate loose
causing serious damage. Especially when dealing
with aluminum parts, pay attention to torque specifi-
cations and utilize a torque wrench in assembly. If a
torque figure is not available, remember that if you
are using the right tool to perform the job, you will
probably not have to strain yourself to get a fastener
tight enough. The pitch of most threads is so slight
that the tension you put on the wrench will be multi-
plied many times in actual force on what you are
tightening. A good example of how critical torque is
can be seen in the case of spark plug installation, es-
pecially where you are putting the plug into an alu-
minum cylinder head. Too little torque can fail to
crush the gasket, causing leakage of combustion
gases and consequent overheating of the plug and
engine parts. Too much torque can damage the
threads or distort the plug, changing the spark gap.
There are many commercial products available for
ensuring that fasteners won’t come loose, even if they
are not torqued just right (a very common brand is
Loctite? If you’re worried
about getting something
together tight enough to hold, but loose enough to
avoid mechanical damage during assembly, one of
these products might offer substantial insurance. Be-
fore choosing a threadlocking compound, read the
label on the package and make sure the product is
compatible with the materials, fluids, etc. involved.
3. Crossthreading. This occurs when a part such
as a bolt is screwed into a nut or casting at the wrong
angle and forced. Crossthreading is more likely to
occur if access is difficult. It helps to clean and lubri-
cate fasteners, then to start threading the bolt, spark
plug, etc. with your fingers If you encounter resis-
tance, unscrew the part and start over again at a dif-
ferent angle until it can be inserted and turned several
times without much effort. Keep in mind that many
parts, especially spark plugs, have tapered threads,
so that gentle turning will automatically bring the part
you’re threading to the proper angle. Don’t put a
wrench on the part until its been tightened a couple
of turns by hand. If you suddenly encounter resis-
tance, and the part has not seated fully, don’t force it.
Pull it back out to make sure it’s clean and threading
properly.
Be sure to take your time and be patient, and al-
ways plan ahead. Allow yourself ample time to per-
form repairs and maintenance You may find main-
taining your car a satisfying and enjoyable
experience.
b See Figures 1 thru 15
Naturally, without the proper tools and equipment
it is impossible to properly service your vehicle. It
would also be virtually impossible
to catalog every
tool that you would need to perform all of the opera-
tions in this book. Of course, It would be unwise for
the amateur to rush out and buy an expensive set of
tools on the theory that he/she may need one or more
of them at some time, The best approach is to proceed slowly, gathering savings will
be far outweighed by frustration and
a good quality set of those tools that are used most mangled knuckles.
frequently Don’t be misled by the low cost of bargain Begin accumulating those tools that are used most
tools. It is far better to spend a little more for better frequently: those associated with routine maintenance
quality. Forged wrenches, 6 or 12-point sockets and and tune-up. In addition to the normal assortment of
fine tooth ratchets are by far preferable to their less screwdrivers and pliers, you should have the follow-
expensive counterparts. As any good mechanic can ing tools:
tell you, there are few worse experiences than trying
l Wrenches/sockets and combination open
to work on a vehicle with bad tools. Your monetary end/box end wrenches in sizes from %-% in. or

l
l-14 GENERALINFORMATIONAND MAINTENANCE
Proper maintenance and tune-up is the key to long
and trouble-free vehicle life, and the work can yield
its own rewards. Studies have shown that a properly
tuned and maintained vehicle can achieve better gas
mileage than an out-of-tune vehicle. As a conscien-
tious owner and driver, set aside a Saturday morning,
say once a month, to check or replace items which
could cause major problems later. Keep your own
personal log to jot down which services you per-
formed, how much the parts cost you, the date, and
the exact odometer reading at the time. Keep all re-
selfer, these receipts are the only proof you have that ceipts for such items as engine oil and filters, so that
they may be referred tp in case of related problems or
to determine operating expenses. As a do-it-your- the required maintenance was performed. In the event
of a warranty problem, these receipts will be invalu-
able.
The literature provided with your vehicle when it
was originally delivered includes the factory recom-
mended maintenance schedule. If you no longer have
this literature, replacement copies are usually avail-
able from the dealer. A maintenance schedule is pro-
vided later in this section, in case you do not have
the factory literature. *
REMOVAL &INSTALLATION
Except 2.gL Turbocharged Engine
b See Figures 36 thru 41 9. Place a new air cleaner element inside the
lower housing. Make sure the seal on the element is
fully seated in the groove.
10. Install the upper air cleaner housing and inlet
tube onto the lower housing.
11. Tighten the clamp on the inlet tube at the
throttle body.
12. Attach the breather hose onto the air inlet tube.
13. Plug the connector into the MAF sensor.
14. Attach the air cleaner housing retaining clips.
15. Connect the negative battery cable.
2.DL Turbocharged Engine
b See Figure 42
1. Disconnect the negative battery cable.
2. Detach the air flow sensor connector.
3. Unfasten the boost hose.
4. Disconnect the solenoid valve with hoses.
93151p50 Fig. 36 Release the retaining clips from the
air cleaner housing
r3151p47 Fig. 37 Unplug the MAF sensor connector
Fig. 49
. . . then remove the air outlet tube
and upper housing from the lower housing 1. Disconnect the negative battery cable. 5. Disconnect the air intake hose.
2. Release the retaining clips from the air 6. Unfasten tie air cleaner retainer bolts and the
cleaner housing. air cleaner assembly.
3. Loosen the clamp on the air outlet tube at the 7. Unclamp the cover and remove from the hous-
throttle body. ing.
4. Detach the breather hose from the air inlet
tube. *Care must be taken when removing the air
cleaner cover. The air flow sensor is at-
5. Unplug the MAF sensor connector.
6. Separate the upper and lower air cleaner tached and could be damaged during cover
removal.
housings and remove the air outlet tube and upper
housing from the lower housing.
7. Remove the air cleaner element from the
housing.
To install:
8. Clean the inside of the air cleaner housing of
any dirt and debris that has collected inside. 8. Remove the air cleaner element. Thoroughly
clean the air cleaner housing prior to replacing the air
filter.
To install:
9. Install the new air cleaner element into the
housing. Install and secure the cover in place.
Fig. 38 Detach the breather hose from the
air tniet tube
Fig. 41 Remove the air cleaner element
from the housing Fig. 39 Loosen the clamp on the air outlet
tube at the throttle body . . .
Fig. 42 Detach the air flow sensor connec-
tor, the boost hose and the solenoid valve
connector

GENERALINFORMATIONAND MAINTENANC-E 1133
Used fluids such as engine oil, transaxle fluid, an-
tifreeze and brake fluid are hazardous wastes and
must be disposed of properly. Before draining any
fluids, consult with your local authorities; in many ar-
eas, waste oil, antifreeze, etc. is being accepted as a
part of recycling programs. A number of service sta-
tions and auto parts stores are also accepting waste
fluids for recycling.
Be sure of the recycling center’s policies before
draining any fluids, as many will not accept different
fluids that have been mixed together.
ENGINE OIL
6 See Figure 148
WMitsubishi recommends that SAE 5W-30
viscosity engine oil should be used for all clia
mate conditions, however, SAE low-30 is ac
ceptable for vehicles operated in moderate-
to-hot climates. the SAE number, the lighter the oil; the lower the vis-
cosity, the easier it is to crank the engine in cold
weather but the less the oil will lubricate and protect
the engine in high temperatures. This number is
marked on every oil container.
Oil viscosity’s should be chosen from those oils
recommended for the lowest anticipated temperatures
during the oil change interval. Due to the need for an
oil that embodies both good lubrication at high tem-
peratures and easy cranking in cold weather, multi-
grade oils have been developed. Basically, a multi-
grade oil is thinner at low temperatures and thicker at
high temperatures. For example, a low-40 oil (the W
stands for winter) exhibits the characteristics of a 10
weight (SAE 10) oil when the car is first started and
the oil is cold. Its lighter weight allows it to travel to
the lubricating surfaces quicker and offer less resis-
tance to starter motor cranking than, say, a straight
30 weight (SAE 30) oil. But atier the ensine reaches
operating temperature, the low-40 oil begins acting
like straight 40 weight (SAE 40) oil, its heavier weight
providing greater lubrication with less chance of
foaming than a straight 30 weight oil. Synthetic oil is not for every car and every type of
driving, so you should consider your engine’s condi-
tion and your type of driving. Also, check your car’s
warranty conditions regarding the use of synthetic oils.
FUEL
All models equipped with a SOHC (Single Over-
head Camshaft) engine are designed to operate using
regular unleaded fuel with a minimum of 87 octane.
All models equipped with a DOHC (Dual Overhead
Camshaft) engine are designed to operate using reg-
ular unleaded fuel with a minimum of 91 octane. Mit-
subishi warns that using gasoline with a lower octane
rating can cause persistent and heavy knocking, and
may cause internal engine damage.
If your vehicle is having problems with rough idle
or hesitation when the enoine is cold, it mav be
caused by low volatility fuel. If this occurs, iry a dif-
ferent grade or brand of fuel.
'OPERATION 1~ FOREIGN COUNTRIES
lccS1235 Fig. 148 look for the API oil identification
Non-detergent motor oils or straight mineral
label when choosing your enaine oil oils should not be used in your engine.
When adding oil to the crankcase or changing the
0 Nil or filter, it is important that oil of an equal quality
I original equipment be used in your car. The use of
. tc mtenor 011s may void the warranty, damage your en-
gine, or both. __
The SAE (Society of Automotive Engineers) grade
number of oil indicates the viscosity of the oil (its
ability to lubricate at a given temperature). The lower
Fig. 149 Grasp the oil level dipstick and pull
upward to remove it from the dipstick
tube
The API (American Petroleum Institute) designa-
tions, also found on the oil container, indicates the
classification of engine oil used under certain given
operating conditions. Only oils designated for use
Service SJ heavy duty detergent should be used in
your car. Oils of the SJ type perform may functions If you plan to drive your car outside the United
States or Canada, there is a possibility that fuels will
be too low in anti-knock quality and could produce
engine damage. It is wise to consult with local au-
thorities upon arrival in a foreign country to deter-
mine the best fuels available.
inside the engine besides their basic lubrication.
Through a balanced system of metallic detergents
and polymeric dispersants, the oil prevents high and
low temperature deposits and also keeps sludge and
dirt particles in suspension. Acids, particularly sulfu-
OILLEVELCHECK ric acid, as well as other by-products of engine com-
bustion are neutralized by the oil. If these acids are
# See Figures 149, 150, and 151
allowed to concentrate, thev can cause corrosion and
rapid wear of the internal engine parts.
Synthetic Oil
There are many excellent synthetic and fuel-effi-
cient oils currently available that can provide better
gas mileage, longer service life and, in some cases,
better engine protection. These benefits do not come
without a few hitches, however; the main one being
the price of synthetic oil, which is significantly more
expensive than conventional oil.
.
The EPA warns that urolonoed contact with used engine oil ma; cause-a number of skin
disorders, including cancer! You should
make every effort to minimize your exposure
to
used engine oil. Protective gloves should
be worn when changing the oil. Wash your
hands and any other exposed skin areas as
soon as possible after exposure to used en-
gine oil. Soap and water, or waterless hand
cleaner should be used.
Fig. 150 Wipe the dipstick clean and rein-
sert it into the dipstick
tube to get the cor-
rect oil level The engine oil dipstick is typically located in the
Fig. 151 The oil level should be between the
marks/notches on the dipstick

ENGINEANDENGINEOVERHAUL 3-57
Anything that generates heat and/or friction WIII
eventually burn or wear out (for example, a light bulb
generates heat, therefore its life span is limited). With
this in mind, a running engine generates tremendous
amounts of both; friction is encountered by the mov-
ing and rotating parts inside the engine and heat is
created by friction and combustion of the fuel How-
ever, the engine has systems designed to help reduce
the effects of heat and friction and provide added
longevrty. The oiling system reduces the amount of
friction encountered by the moving parts inside the
engine, while the cooling system reduces heat cre-
ated by friction and combustion If either system is
not maintained, a break-down will be inevitable.
Therefore, you can see how regular maintenance can
affect the service life of your vehicle, If you do not
drain, flush and refill your cooling system at the
proper intervals, deposits WIII begin to accumulate in
the radiator, thereby reducing the amount of heat it
can extract from the coolant The same applies to
your oil and filter; If it is not changed often enough it
becomes laden with contaminates and is unable to
properly lubricate the engine. This increases friction
and wear.
There are a number of methods for evaluating the
condition of your engine. A compression test can re-
veal the condition of your pistons, piston rings,
cylinder bores, head gasket(s), valves and valve
seats. An oil pressure test can warn you of possible
engine bearing, or oil pump failures. Excessrve oil
consumption, evidence of oil in the engine air intake
area and/or bluish smoke from the tailpipe may indi-
cate worn piston rings, worn valve guides and/or
valve seals. As a general rule, an engine that uses no
more than one quart of oil every 1000 miles is in
good condition. Engines that use one quart of oil or
more in less than 1000 miles should first be checked
for oil leaks. If any oil leaks are present, have them
fixed before determining how much oil is consumed
by the engine, especrally if blue smoke is not visible
at the tailpipe
COMPRESSION TEST
# See Figure 226
tccs3801 Fig. 226 A screw-in type compression gauge
is more accurate and easier to use without
an assistant
A noticeable lack of engine power, excessive oil
consumption and/or poor fuel mileage measured
over an extended period are all indicators of internal
engine wear. Worn piston rings, scored or worn
cylinder bores, blown head gaskets, sticking or burnt
valves, and worn valve seats are all possible culprits.
A check of each cylinders compression WIII help lo-
cate the problem.
*A screw-in type compression gauge is
more accurate than the type you simply hold
against the spark plug hole. Although it takes
slightly longer to use, it’s worth the effort to
obtain a more accurate reading.
1 Make sure that the proper amount and vis-
cosity of engine oil is in the crankcase, then ensure
the battery is fully charged.
2. Warm-up the engine to normal operating
temperature, then shut the engine
OFF. 3. Disable the ignition system.
4. Label and disconnect all of the spark plug
wires from the plugs,
5. Thoroughly clean the cylinder head area
around the spark plug ports, then remove the spark
plugs.
6. Set the throttle plate to the fully open (wide-
open throttle) position You can block the accelerator
linkage open for this, or you can have an assistant
fully depress the accelerator pedal.
7. Install a screw-in type compression gauge
into the No. 1 spark plug hole until the fitting is snug.
Be careful not to crossthread the spark plug
hole.
8. According to the tool manufacturers instruc-
tions, connect a remote starting switch to the starting
circuit.
9. With the ignition switch in the
OFF position,
use the remote starting switch to crank the engine
through at least five compression strokes (approxi-
mately 5 seconds of cranking) and record the highest
reading on the gauge
10. Repeat the test on each cylinder, cranking the
engine approximately the same number of compres-
sion strokes and/or time as the first.
11. Compare the hrghest readings from each
cylinder to that of the others. The indicated compres-
sion pressures are considered within specifications if
the lowest reading cylinder is within 75 percent of the
pressure recorded for the highest reading cylinder
For example, if your highest reading cylinder pres-
sure was 150 psi (1034 kPa), then 75 percent of that
would be 113 psi (779 kPa). So the lowest reading
cylinder should be no less than 113 psi (779 kPa).
12. If a cylinder exhibits an unusually low com-
pression reading, pour a tablespoon of clean engine
oil into the cylinder through the spark plug hole and
repeat the compression test. If the compression rises
after adding oil, it means that the cylinder’s piston
rings and/or cylinder bore are damaged or worn, If
the pressure remains low, the valves may not be seat-
ing properly (a valve job is needed), or the head gas-
ket may be blown near that cylinder. If compression in any two adjacent cylinders is low, and if the addi-
tion of oil doesn’t help raise compression, there is
leakage past the head gasket. Oil and coolant in the
combustion chamber, combined with blue or con-
stant white smoke from the tailpipe, are symptoms of
this problem. However, don’t be alarmed by the nor-
mal white smoke emitted from the tailpipe during en-
gine warm-up or from cold weather driving. There
may be evidence of water droplets on the engine dip-
stick and/or oil droplets in the cooling system if a
head gasket is blown.
OIL PRESSURETEST
Check for proper oil pressure at the sending unit
passage with an externally mounted mechanical oil
pressure gauge (as opposed to relying on a factory
Installed dash-mounted gauge). A tachometer may
also be needed, as some specifications may require
running the engine at a specific rpm.
1. With the engine cold, locate and remove the oil
pressure sending unit.
2. Followrng the manufacturers instructions,
connect a mechanical oil pressure gauge and, if nec-
essary, a tachometer to the engine.
3 Start the engine and allow it to idle.
4 Check the oil pressure reading when cold and
record the number. You may need to run the engine
at a specified rpm, so check the specifications,
5. Run the engine until normal operating temper-
ature is reached (upper radiator hose will feel warm)
6. Check the oil pressure reading again with the
engine hot and record the number. Turn the engine
OFF. 7. Compare your hot oil pressure reading to that
given in the chart If the reading is low, check the
cold pressure reading against the chart. If the cold
pressure IS well above the specification, and the hot
reading was lower than the specification, you may
have the wrong viscosity oil in the engine. Change
the oil, making sure to use the proper grade and
quantity, then repeat the test.
Low oil pressure readings could be attributed to
internal component wear, pump related problems, a
low oil level, or oil viscosity that is too low. High oil
pressure readings could be caused by an overfilled
crankcase, too htgh of an oil viscosity or a faulty
pressure relief valve.
Now that you have determined that your engine is
worn out, you must make some decisions. The ques-
tion of whether or not an engine IS worth rebuilding
is largely a subjective matter and one of personal
worth. Is the engine a popular one, or IS it an obso-
lete model? Are parts available? Will it get acceptable
gas mileage once It is rebuilt? Is the car its being put
into worth keeping? Would it be less expensive to
buy a new engine, have your engine rebuilt by a pro,
rebuild it yourself or buy a used engine from a sal-
vage yard? Or would It be simpler and less expensive
to buy another car? If you have considered all these
matters and more, and have still decided to rebuild
the engine, then it is time to decide how you will re-
build it.

3-60 ENGINE/
-w
remove any covers remaining on the engine such as
on today’s automobiles: the Overhead Valve (OHV)
and the Overhead Camshaft (OHC). The latter can
also be broken down into two subgroups: the Single the rocker arm, front or timing cover and oil pan.
Overhead Camshaft (SOHC) and the Dual Overhead
Camshaft (DOHC). Generally, if there is only a single
camshaft on a head. it is iust referred to as an OHC Some front covers may require the vibration damper
and/or crank pulley to be removed beforehand. The
idea is to reduce the engine to the bare necessities
(cylinder head(s), valve train, engine block, crank-
shaft, pistons and connecting rods), plus any other
‘in block’ components such as oil pumps, balance
shafts and auxiliary shafts.
Finally, remove the cylinder head(s) from the en-
gine block and carefully place on a bench. Disassem-
bly instructions for each component follow later in
this section.
There are two basic types of cylinder heads used
Most cylinder heads these days are made of an
aluminum alloy due to its light weight, durability and
L--L I _--- 1^- _..^ I:,:^^ I I ^...^. .^_ ^^^I :_-_ ..^^ ,L- same environment. The same goes for any other unchanged. One aspect to pay attention to is careful
component on the cylinder head. Think of it as an in- labeling of the parts on the dual camshaft cylinder
“’ surance policy against future problems related to that head. There will be an intake camshaft and followers
component. as well as an exhaust camshaft and followers and
Unfortunately, the only way to find out which com- they must be labeled as such. In some cases, the
ponents need replacing, is to disassemble and care- components are identical and could easily be in-
fully check each piece. After the cylinder head(s) are stalled incorrectly. DO NOT MIX THEM UP! Deter-
disassembled, thoroughly clean all of the compo- mining which is which is very simple; the intake
nents. camshaft and components are on the same side of
DISASSEMBLY the head as was the intake manifold. Conversely, the
exhaust camshaft and components are on the same
side of the head as was the exhaust manifold.
ti See Figures 237 and 238
Whether it is a single or dual overhead camshaft Cup Type Camshaft Followers
cylinder head, the disassembly procedure is relatively 6 See Figures 239, 240, and 241
t “” ““’ 1 Most cylinder heads with cup type camshaft fol-
1 1 head. Also, an engine with an OHV cylinder head is j:, ’
I also known as a pushrod engine. : .; :-,
_I lowers will have the valve spring, retainer and locks
recessed within the followers bore. You will need a
C-clamp style valve spring compressor tool, an OHC
spring removal tool (or equivalent) and a small mag-
net to disassemble the head.
1. If not already removed, remove the camshaft(s)
and/or followers, Mark their positions for assembly.
2. Position the cylinder head to allow use of a C-
clamp style valve spring compressor tool.
IIRN il~llSlt?l ~Lldll~l~S. IlUWttVtJ, MS1 11011 W8S lilt: material of choice in the past, and is still used on
many vehicles today. Whether made from aluminum
or iron, all cylinder heads have valves and seats.
Some use fwo valves per cylinder, while the more hi-
tech engines will utilize a multi-valve configuration
using 3‘4 and even 5 valves per cylinder. When the
valve contacts the seat, it does so on precision ma-
chined surfaces, which seals the combustion cham-
ber, All cylinder heads have a valve guide for each
valve. The auide centers the valve to the seat and al-
lows it to move up and down within it. The clearance
between the valve and guide can be critical. Too
much clearance and the engine may consume oil,
lose vacuum and/or damaae the seat. Too little. and
the valve can stick in the guide causing the engine to
run poorly if at all, and possibly causing severe dam-
age. The last component all cylinder heads have are
valve springs. The spring holds the valve against its
seat. It also returns the valve to this position when
the valve has been opened by the valve train or
camshaft. The spring is fastened to the valve by a re-
tainer and valve locks (sometimes called keepers).
Aluminum heads will also have a valve spring shim
to keep the spring from wearing away the aluminum. Fig, 237 Exploded view of a valve, seal,
1 cylinder head ----r- 1 spring, retamer and locks from an OHC
An ideal method of rebuilding the cylinder head
would involve replacing all of the valves, guides,
seats, springs, etc. with new ones. However, depend-
ing on how the engine was maintained, often this is
not necessary. A major cause of valve, guide and seat
wear is an improperly tuned engine. An engine that is
~~f~t~~ rich, will often wash the lubricating oil
out ofthe guide with gasoline, causing it to wear
~~fdfy. lonely, an engine which is running too
lean wifl pface higher combustion temperatures on
Me valves and seats allowing them to wear or even
bum. Springs fall victim to the driving habits of the
f~~iduaf. A driver who often runs the engine rpm to
tfre redfine will wear out or break the springs faster
then one tfrat stays well below it. Unfortunately,
mileage takes it tot1 on all of the parts. Generally, the
valves, guides, springs and seats in a cylinder head
can be machined and re-used, saving you money.
.However, if a valve is burnt, it may be wise to replace
all of the valves, since they were all operating in the oi a multi-valve cylinder
t has 2 intake
and 2 ex-
At is preferred to position the cylinder head lasket’surtace facing you with tee valve
springs facing the opposite direction and the
lead laying horizontal.
3. With the OHC spring removal adapter tool po-
,itioned inside of the follower bore, compress the
alve spring using the C-clamp style valve spring
:ompressor.
tcca3p51 fig. 239 C-clamp type spring compressor
and an OHC spring removal tool (center) for
cup type followers
Fig. 240 Most cup type follower cylinder
/ heads retain the camshaft using bolt-on
bearing caps