Tune-Up General Information; Minor Tune-Up; Major Tune-Up; Fluid Level Checks - Jeep cherokee 1989 Owner's Manual

2 Introduction
This Chapter is designed to help the home mechanic maintain the
Jeep Cherokee or Comanche with the soak of maximum ~erformance,
economy, safety and reliability in mind.
Included is a master maintenance schedule (page 33), followed by
procedures dealing specifically with each item on the schedule. Visual
checks, adjustments, component replacement and other helpful items
are included. Refer to the accompanying illustrations of the engine com-
partment and the underside of the vehicle for the locations of various
components.
Servicing your vehicle in accordance with the mileageltime mainte-
nance schedule and the step-by-step procedures will result in a planned
maintenance program that should produce a long and reliable service
life. Keep in mind that it is a comprehensive plan, so maintaining some
items but not others at the specified intervals will not produce the same
results.
As you service your vehicle, you will discover that many of the pro-
cedures can and should be grouped together because of the nature
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of the particular procedure you're performing or because of the close
proximity of t w o otherwise unrelated components to one another.
For example, if the vehicle is raised for chassis lubrication, you should
inspect the exhaust, suspension, steering and fuel systems while you're
under the vehicle. When you're rotating the tires, it makes good sense
to check the brakes since the wheels are already removed. Finally, let's
suppose you have to borrow or rent a torque wrench. Even if you only
need it to tighten the spark plugs, you might as well check the torque
of as many critical fasteners as time allows.
The first step in this maintenance program is to prepare yourself
before the actual work begins. Read through all the procedures you're
planning to do, then gather up all the parts and tools needed. If it looks
like you might run into problems during a particular job, seek advice
from a mechanic or an experienced do-it-yourselfer.

3 Tune-up general information

The term tune-up is used in this manual to represent a combination
of individual operations rather than one specific procedure.
If, from the time the vehicle is new, the routine maintenance schedule
is followed closely and frequent checks are made of fluid levels and
high wear items, as suggested throughout this manual, the engine will
be kept in relatively good running condition and the need for additional
work will be minimized.
More likely than not, however, there will be times when the engine
is running poorly due to lack of regular maintenance. This is even more
likely if a used vehicle, which has not received regular and frequent
maintenance checks, is purchased. In such cases, an engine tune-up
will be needed outside of the regular routine maintenance intervals.
The first step in any tune-up or diagnostic procedure to help correct
a poor running engine is a cylinder compression check. A compression
check (see Chapter 2 Part D) will help determine the condition of internal
engine components and should be used as a guide for tune-up and repair
procedures. If, for instance, a compression check indicates serious in-
ternal engine wear, a conventional tune-up will not improve the per-
formance of the engine and would be a waste of time and money.
Because of its importance, the compression check should be done by
someone with the right equipment and the knowledge to use it properly.
The following procedures are those most often needed to bring a
generally poor running engine back into a proper state of tune.

Minor tune-up

Check all engine related fluids (Section 4 )
Clean, inspect and test the battery (Section 8)
Check and adjust the drivebelts (Section 26)
Replace the spark plugs (Section 43)
lnspect the distributor cap and rotor (Section 45)
lnspect the spark plug and coil wires (Section 44)
Check and adjust the ignition timing (Section 33)
Check the PCV valve or CCV hose(Section 40)
Check the air and PCV filters (Section 32)
Check the cooling system (Section
Check all underhood hoses (Section 10)
The Motor Manual Guy
Chapter 1 Tune-up and routine maintenance

Major tune-up

Check the EGR system (Section 42)
Check the ignition system (Chapter 5)
Check the charging system (Chapter 5)
Check the fuel system (Section 21
Replace the air and PCV filters (Section 32)
Replace the distributor cap and rotor (Section 45)
Replace the spark plug wires (Section 44)

4 Fluid level checks

Note: The following are fluid level checks to be done on a 250 mile
or weekly basis. Additional fluid level checks can be found in specific
maintenance procedures which follow. Regardless of intervals, be alert
to fluid leaks under the vehicle which would indicate a fault to be cor
rected immedia tely.
1 Fluids are an essential part of the lubrication, cooling, brake, clutch
and windshield washer systems. Because the fluids gradually become
depleted andlor contaminated during normal operation of the vehicle,
they must be periodically replenished. See Recommended lubricants
and fluids at the beginning of this Chapter before adding fluid to any
of the following components. Note: The vehicle must be on levelground
when fluid levels are checked.
Engine oil
Refer to illustrations 4.4 and 4.6
2 The engine oil level is checked with a dipstick that extends through
a tube and into the oil pan at the bottom of the engine.
3 The oil level should be checked before the vehicle has been driven,
or about 15 minutes after the engine has been shut off. If the oil is
checked immediately after driving the vehicle, some of the oil will re-
main in the upper engine components, resulting in an inaccurate reading
on the dipstick.
4 Pull the dipstick from the tube and wipe all the oil from the end
with a clean rag or paper towel. Insert the clean dipstick all the way
back into the tube, then pull it out again. Note the oil at the end of
the dipstick. Add oil as necessary to keep the level between the ADD
mark and the FULL mark on the dipstick (see illustration).
5 Do not overfill the engine by adding too much oil since this may
result in oil fouled spark plugs, oil leaks or oil seal failures.
4.4 Checking the oil level on an inline six-cylinder engine (on V6
engines, the dipstick is on the driver's side of the engine; on four-
cylinder engines, it's on the passenger's side)
should be at or near the FULL mark
to bring the level t o or near the FULL mark (it takes one quart t o
raise the level from ADD to FULL)
1-7
. . .
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the oil level
if it isn't, add enough oil