1900 MITSUBISHI DIAMANTE alarm

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l-16 GENERALINFORMATIONAND MAINTENANCE
Fig. 49 Grasp the valve and gently remove
Fig. 50 Twist and pull on the valve to re-
it from the valve cover
move it from the hose Fig. 51 Inspect the grommet and replace if
cracked or leaking oil
SERVICING
corrosive acid can also eat away at components un-
der the hood.
Always visually inspect the battery case for cracks,
leakage and corrosion. A white corrosive substance
u See Figure 52
The evaporative canister requires no periodic ser-
vicing. However, a careful inspection of the canister
and hoses should be made frequently, Replace dam- on the battery case or on nearby components would
indicate a leaking or cracked battery. If the battery is
cracked, it should be replaced immediately. GENERALMAINTENANCE '_
devices that increase parasitic load may discharge a
battery sooner. If the vehicle is to be stored for 6-B
weeks in a secure area and the alarm system, if pre-
sent, is not necessary, the negative battery cable
should be disconnected at the onset of storage to
protect the battery charge.
Remember that constantly discharging and
recharging will shorten battery life. Take rare not to
allow a battery to be needlessly discharged.
aged components as required.
The canister is typically located under one of the
front fenders, however on some later models it may
be under the rear of the vehicle, near the gas tank,
r on most models # See Figure 53
A battery that is not sealed must be checked peri-
odically for electrolyte level. You cannot add water to
a sealed maintenance-free battery (though not all
maintenance-free batteries are sealed); however, a
sealed battery must also be checked for proper elec-
trolyte level, as indicated by the color of the built-in
hydrometer “eye.”
Always keep the battery cables and terminals free
of corrosion. Check these components about once a
year. Refer to the removal, installation and cleaning
procedures outlined in this section,
Keep the top of the battery clean, as a film of dirt
can help completely discharge a battery that is not
used for long periods. A solution of baking soda and
water may be used for cleaning, but be careful to
flush this off with clear water. DO NOT let any of the
solution into the filler holes. Baking soda neutralizes
battery acid and will de-activate a battery cell.
Batteries in vehicles which are not operated on a
regular basis can fall victim to parasitic loads (small
BA-ITERY FLUID
Check the battery electrolyte level at least once a
month. or more often in hot weather or during peri-
ods of extended vehicle operation. On non-sealed
batteries, the level can be checked either through the
case on translucent batteries or by removing the cell
caps on opaque-cased types. The electrolyte level in
each cell should be kept filled to the split ring inside
each ceil, or the line marked on the outside of the
case.
If the level is low, add only distilled water through
the opening until the level is correct. Each cell is sep-
arate from the others, so each must be checked and
filled individuallv. Distilled water should be used, be-
cause the chemicals and minerals found in most
drinking water are harmful to the battery and could
significantly shorten its life.
If water is added in freezing weather, the vehicle
should be driven several miles to allow the water to
mix with the electrolyte. Otherwise, the battery could
freeze.
current drains which are constantly drawing current
from the battery). Normal parasitic loads may drain a Although some maintenance-free batteries have
removable cell caos for access to the electrolyte, the
cause a short circuit, leading to sparks and possible
personal injury.
Do not smoke, have an open flame or create
sparks near a battery; the gases contained in the bat-
tery are very explosive and, if ignited, could cause se-
vere injury or death.
All batteries, regardless of type, should be care-
fully secured by a battery hold-down device. If this is
not done, the battery terminals or casing may crack
from stress applied to the battery during vehicle oper-
ation. A battery which is not secured may allow acid
to leak out, making it discharge faster; such leaking m / built-in hydrometer. .

*Although the readings from built-in hy-
drometers found in sealed batteries may
vary, a green eye usually indicates a prop
erly charged battery with sufficient fluid
level. A dark eye is normally an indicator of a
battery wlth sufficient fluid, but one which
may be low in charge. And a light or yellow
eye is usually an indication that electrolyte
supply has dropped below the necessary
tcu1@32 Fig. 53 A typical location for the built-in hv- level for battery (and hydrometer) operation.
drometer on maintenan
ce-free batteries ’ I In this last case. sealed batteries with an in-
sufficient electrolyte level must usually be
’ discarded.

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.