GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 132
Some electrical components which require
a large amount of current to operate
use a special switch called a relay. Sinc e these circuits carry a large amount of
current, the thickness of the wire in the ci rcuit is also greater. If this large wire
were connected from the load to the c ontrol switch, the switch would have to
carry the high amperage load and the fair ing or dash would be twice as large to
accommodate the increased size of t he wiring harness. To prevent these
problems, a relay is used.
Relays are composed of a coil and a se t of contacts. When the coil has a
current passed though it, a magnetic fiel d is formed and this field causes the
contacts to move together, completing the circuit. Most relays are normally
open, preventing current from passing thr ough the circuit, but they can take any
electrical form depending on th e job they are intended to do. Relays can be
considered "remote control switches." They allow a smaller current to operate
devices that require higher amperages. W hen a small current operates the coil,
a larger current is allo wed to pass by the contacts. Some common circuits
which may use relays are the horn, headlight s, starter, electric fuel pump and
other high draw circuits.
Fig. 3: Relays are composed of a coil and a switch. These two components are
linked together so that w hen one operates, the other operat es at the same time.
The large wires in the circuit are connect ed from the battery to one side of the
relay switch (B+) and from the opposite side of the re lay switch to the load
(component). Smaller wires are connected from the relay coil to the control
switch for the circuit and from the opposite side of the relay coil to ground
LOAD
Every electrical circuit must include a "load" (something to use the electricity
coming from the source). Without this l oad, the battery would attempt to deliver
its entire power supply from one pole to another. This is called a "short circuit."
All this electricity would take a short cut to ground and cause a great amount of
damage to other components in the circui t by developing a tremendous amount
of heat. This condition could develop suffici ent heat to melt the insulation on all
the surrounding wires and reduce a multiple wire cable to a lump of plastic and
copper.
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 443
Ensure that oil holes are properly al
igned. Replace camshaft rear plug, and
stake it into position to aid retention.
INSPECTION
CAMSHAFT LOBE LIFT
Check the lift of each lobe in consecutiv e order and make a note of the reading.
1. Remove the fresh air inlet tube a nd the air cleaner. Remove the heater
hose and crankcase ventilation hoses. Remove valve rocker arm
cover(s).
2. Remove the rocker arm stud nut or fulcrum bolts, fulcrum seat and rocker
arm.
3. Make sure the pushrod is in the valve tappet socket. Install a dial indicator so that the actuating poin t of the indicator is in the pushrod
socket (or the indicator ball socket adapter tool is on the end of the
pushrod) and in the same plane as the pushrod movement.
4. Disable the ignition and fuel systems.
5. Install a remote starter switch. Crank the engine with the ignition and fuel
system disabled. Turn the crankshaft ov er until the tappet is on the base
circle of the camshaft lobe. At this position, the pushrod will be in its
lowest position.
6. Zero the dial indicator. Continue to rotate the crankshaft slowly until the
pushrod is in the fully raised position.
7. Compare the total lift recorded on the dial indicator with the specification
shown on the Camshaft Specification chart.
To check the accuracy of the original in dicator reading, continue to rotate the
crankshaft until the indicator reads zero. If the lift on any lobe is below specified
wear limits listed, the ca mshaft and the valve tappet operating on the worn
lobe(s) must be replaced.
8. Install the rocker arm, fulcrum seat and stud nut or fulcrum bolts. Adjust
the valves, if required (r efer to the valves procedure in this section).
9. Install the valve rocker arm cover(s) and the air cleaner.
CAMSHAFT END PLAY
On all gasoline V8 engi nes, prying against the aluminum-nylon camshaft
sprocket, with the valve train load on t he camshaft, can break or damage the
sprocket. Therefore, the rocker arm adj usting nuts must be backed off, or the
rocker arm and shaft assembly must be loosened sufficiently to free the
camshaft. After checking the camshaft e nd play, check the valve clearance.
Adjust if required (refer to procedure in this section).
1. Push the camshaft toward the rear of the engine. Install a dial indicator or
equivalent so that the indicator point is on the camshaft sprocket
attaching screw.
GM – CAMARO 1982-1992 – Repair Guide (Checked by WxMax) 467
8. According to the tool manufacture
r's instructions, 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
(approximately 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 compression stroke s and/or time as the first.
11. Compare the highest readi ngs from each cylinder to that of the others.
The indicated compression pre ssures are considered within
specifications if the lo west reading cylinder is within 75 percent of the
pressure recorded for the highest readi ng cylinder. For example, if your
highest reading cylinder pressure 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 compression reading, pour a
tablespoon of clean engine oil into the cylinder through the spark plug
hole and repeat the compression tes t. 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 re mains low, the valves may not be
seating properly (a valve job is needed), or the head gasket may be
blown near that cylinder. If compressi on in any two adjacent cylinders is
low, and if the addition 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 const ant white smoke from the tail pipe,
are symptoms of this pr oblem. However, don't be alarmed by the normal
white smoke emitted from the tail pipe during engine warm-up or from
cold weather driving. There may be evidence of water droplets on the
engine dipstick and/or oil droplets in the cooling system if a head gasket
is blown.
OIL PRESSURE TEST
Check for proper oil pressu re at the sending unit passage with an externally
mounted mechanical oil pressure gauge (a s opposed to relying on a factory
installed dash-mounted gauge). A tachom eter may also be needed, as some
specifications may require running the engine at a specific rpm.
1. With the engine cold, locate and remo ve the oil pressure sending unit.
2. Following the manufacturer's inst ructions, connect a mechanical oil
pressure gauge and, if necessary, 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 chart located earlier in this section.
5. Run the engine until normal operati ng temperature is reached (upper
radiator hose will feel warm).
6. Check the oil pressure reading agai n with the engine hot and record the
number. Turn the engine OFF.