Engine Performance; Honing Cylinder Bores - Jeep Wrangler 1997 Manual

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ENGINE
GENERAL INFORMATION (Continued)
CAUTION : DO NOT overspeed the engine.
inch) drop is placed in the center of the gasket con-
tact area . Uncured sealant may be removed with a
shop towel. Components should be torqued in place
while the sealant is still wet to the touch (within 10
minutes) . The use of a locating dowel is recom-
mended during assembly to prevent smearing the
material off location .
Mopar Gasket Maker should be applied sparingly
to one gasket surface. The sealant diameter should
be 1.00 mm (0.04 inch) or less . Be certain the mate-
rial surrounds each mounting hole. Excess material
can easily be wiped off. Components should be
torqued in place within 15 minutes. The use of a
locating dowel is recommended during assembly to
prevent smearing the material off location.
ENGINE PERFORMANCE
To provide best vehicle performance and lowest
vehicle emissions, it is most important that the
tune-up be done accurately. Use the specifications
listed on the Vehicle Emission Control Information
label found on the engine compartment hood.
(1) Test battery specific gravity. Add water, if nec-
essary . Clean and tighten battery connections.
(2) Test cranking amperage draw (refer to Group 8B,
Battery/Starter Service for the proper procedures).
(3) Tighten the intake manifold bolts (refer to
Group 11, Exhaust System and Intake Manifold for
the proper specifications) .
(4) Perform cylinder compression test:
(a) Check engine oil level and add oil, if neces-
sary.
(b) Drive the vehicle until engine reaches nor-
mal operating temperature .
(c) Select a route free from traffic and other
forms of congestion, observe all traffic laws and
briskly accelerate through the gears several times.
The higher engine speed may help clean out valve
seat deposits which can prevent accurate compres-
sion readings.
(d) Remove all spark plugs from engine . As
spark plugs are being removed, check electrodes for
abnormal firing indicators-fouled, hot, oily, etc.
Record cylinder number of spark plug for future
reference.
(e) Disconnect coil wire from distributor and
secure to good ground to prevent a spark from
starting a fire .
(f) Be sure throttle blades are fully open during
the compression check.
(g) Insert compression gage adaptor into the
No.l spark plug hole . Crank engine until maxi-
mum pressure is reached on gauge. Record this
pressure as No.l cylinder pressure .
TJ
(h)
Repeat Step 4g for all remaining cylinders.
(i) Compression should not be less than 689 kPa
(100 psi) and not vary more than 172 kPa (25 psi)
from cylinder to cylinder.
(j) If cylinder(s) have abnormally low compres-
sion pressures, repeat procedure.
(k) If the same cylinder(s) repeat an abnormally
low reading, it could indicate the existence of a
problem in the cylinder.
NOTE: The recommended compression pressures
are to be used only as a guide to diagnosing engine
problems . An engine should NOT be disassembled
to determine the cause of low compression unless
some malfunction is present.
(5)
Clean or replace spark plugs as necessary.
Adjust gap (refer to Group 8D, Ignition System for
gap adjustment and torque).
(6) Test resistance of spark plug cables (refer to
Group 8D, Ignition System).
(7) Inspect the primary wire . Test coil output volt-
age, primary and secondary resistance . Replace parts
as necessary (refer to Group 8D, Ignition System and
make necessary adjustment).
(8) Perform a combustion analysis .
(9) Test fuel pump for pressure (refer to Group 14,
Fuel System for the proper specifications).
(10) Inspect air filter element (refer to Group 0,
Lubrication and Maintenance for the proper proce-
dure).
(11) Inspect crankcase ventilation system (refer to
Group 0, Lubrication and Maintenance for the proper
procedure) .
(12) For emission controls refer to Group 25, Emis-
sion Controls System for service procedures .
(13) Inspect and adjust accessory belt drives (refer
to Group 7, Cooling System for the proper adjust-
ments) .
(14) Road test vehicle as a final test.
HONING CYLINDER BORES
Before honing, stuff plenty of clean shop towels under
the bores and over the crankshaft to keep abrasive
materials from entering the crankshaft area.
(1) Used carefully, the Cylinder Bore Sizing Hone
C-823 equipped with 220 grit stones, is the best tool for
this job. In addition to deglazing, it will reduce taper
and out-of-round as well as removing light scuffing,
scoring or scratches. Usually a few strokes will clean up
a bore and maintain the required limits .
CAUTION : DO NOT use rigid type hones to remove
cylinder wall glaze.
(2)
Deglazing of the cylinder walls may be done if
the cylinder bore is straight and round. Use a cylin-