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Ausbildung
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Inhalt:
Student Objectives
Upon completion of this lesson, you will be able to:
The purpose of this course is to provide an understanding of the major
systems of an automobile and how they function.
These systems are:
 | Internal combustion engine (including lubrication and engine
cooling)
| Electrical Systems
| Electrical Accessories
| Engine fuel and emission control systems
| Automotive drivetrain
| Transmissions, manual and automatic
| Wheels and tires
| Steering systems
| Suspension systems
| Brake systems
| The body (vehicle construction) |
| | | | | | | | | |
Internal Combustion Engine
An internal combustion engine changes potential energy, contained in the
fuel, into mechanical force and motion
 .
Torque
The energy produced by the engine provides a rotational force called
torque which is then used to propel the vehicle. Energy is created when
a mixture of air and fuel burns in the engine's cylinders -- hence the
name "internal combustion".
An internal combustion engine changes potential energy, contained in the
fuel, into mechanical force and motion.
Engine Cylinders
Most automotive engines today consist of four, six, or eight cylinders.
A cylinder is a round hole machined into the engine block that accepts a
piston. The cylinders are arranged either in a straight line, as in an
in-line engine, or with two banks of in-line cylinders in a
"V" pattern, as in V engine.
Transverse and Longitudinal Engines
Most engines are located in the front of the vehicle, mounted in a
longitudinal or transverse position. This simply means that the engine
is mounted in front of the passenger compartment, either facing front to
back (longitudinal), or side to side (transverse). Longitudinal engines
are primarily used in rear-wheel drive vehicles, and transverse engines
are used for front-wheel drive. Both designs are used frequently.
OHC and OHV
Currently, there are two types of designs used in the automobile engine
for the placement of the valves and camshaft. They are the overhead
valve (OHV) and the overhead cam (OHC). Both designs have their valves
mounted above the cylinders in the cylinder head. It is the location of
the camshaft, which operates the valves, that distinguishes the two
designs.
If the camshaft is located in the cylinder head, the engine is called an
overhead cam design. If the camshaft is located in the engine block, the
engine is called an overhead valve design. A dual overhead cam (DOHC)
engine has two camshafts on each cylinder head, one camshaft to operate
the intake valves, while the other one operates the exhaust valves.
System Operation: OHV Valve Train
On an overhead valve engine (OHV), the camshaft is located in the engine
block. The camshaft uses lifters, push rods, and rocker arms to activate
the valves. Its operation is fairly simple. As the camshaft rotates,
each off-center (eccentric) cam lobe pushes against a lifter. The upward
motion of the lifter is transferred through the push rod and onto the
rocker arm.
The upward motion is changed to downward motion as the rocker arm
pivots. The downward motion is then used to open the valve. As the
camshaft continues to rotate, the lobe passes by the lifter and allows
the valve to close. A spring is attached to the valve which returns the
valve to its seated position.
Intake Valve/Exhaust Valve
Every cylinder in the internal combustion engine contains at least two
valves. One intake valve and one exhaust valve. Both valves are used to
open and close internal passages in the cylinder head.
The intake valve is the larger of the two valves. It controls the flow
of the fuel mixture (gasoline) or air (diesel) into the combustion
chamber. The exhaust valve controls the flow of exhaust gases out of the
cylinder.
Valve Design Characteristics
The valves consist of a round head, a stem and a groove at the top of
the valve. The head of the valve is the larger end that opens and closes
the passageway to and from the combustion chamber. The stem guides the
valve up and down and supports the valve spring. The groove at the top
of the valve stem holds the valve spring in place with a retainer lock.
The valves must open and close in order for the air/fuel mixture to
enter and exit the combustion chamber. The opening and closing of the
valves must be properly timed in order for the engine to run smoothly.
Valve operation (sequence and timing) is controlled by the camshaft.
Camshaft
The camshaft consists of several camshaft journals and a set of cam
lobes. The camshaft journals, like the crankshaft journals, are used
to hold the camshaft in place. A bearing is placed around each
journal, allowing it to rotate freely. The cam lobes are used to open
the intake and exhaust valves in each cylinder. The number of cam
lobes equals the number of valves in an engine.
Camshaft Design Characteristics
The angular positioning of the cam lobes on the shaft determines the
sequence of the valves opening and closing. The design of the lobes
determines how high the valves will open (lift) and how long they will
remain open (duration). These designs vary from one engine to another.
The engine is the heart of the automobile as it supplies the power that
drives the wheels.
Controlling the combustion of the air/fuel mixture is a very important
and complex process. It requires that four essential steps take place at
the correct time and in the correct sequence. This has to happen in
every cylinder of the engine. This process is known as the four-stroke
cycle.
The steps include:
| Admitting the proper mixture of air and fuel into the cylinder
| Compressing or squeezing the air and fuel mixture so it will burn
better and deliver more power
| Igniting and burning the mixture
| Removing the burned gases from the cylinder so that the process
can begin again
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Piston Strokes
The name "four-stroke" is derived from the number of piston
strokes required to complete the combustion cycle. A stroke is the
movement of the piston from its highest position in the cylinder
(top-dead-center) to its lowest (bottom-dead-center); or from the lowest
to highest position. The four strokes are called intake, compression,
power, and exhaust. Each cylinder of the engine completes the combustion
cycle at a different time.
Intake Stroke
The intake stroke is the first of the four strokes in the combustion
cycle. As the piston moves away from the top of the cylinder, the intake
valve opens. The downward movement of the piston creates a vacuum
(negative pressure) in the cylinder. The greater pressure outside the
cylinder (ambient pressure) pushes a mixture of air and fuel into the
cylinder. Just after the piston reaches the bottom of the cylinder, the
intake valve closes.
Compression Stroke
The second stroke in the four-stroke cycle is the compression stroke.
The compression stroke begins as the piston starts to move upward in the
cylinder. The intake valve closes, trapping the air-fuel mixture in the
cylinder. Upward movement of the piston compresses the air-fuel mixture
into a very small area.
Compressing or squeezing the mixture is very important for developing
maximum power. The higher the compression, the greater pressure exerted
on the piston when the air/fuel mixture is ignited. Compression also
"pre-heats" the mixture which helps it to burn more
efficiently.
Power Stroke
The third stroke in the four-stroke cycle is the power stroke. The power
stroke begins as the compressed air/fuel mixture is ignited in the
combustion chamber. A spark plug, located in the cylinder head, creates
an electrical spark in the combustion chamber which ignites the air/fuel
mixture. The burning fuel rapidly expands, creating a very high pressure
against the top of the piston.
This pressure drives the piston downward. The downward motion provides
the power that turns the crankshaft and drives the wheels to propel the
vehicle. Up and down movement of the piston on all four strokes is
converted to rotary motion by the crankshaft.
Exhaust Stroke
The final stroke of the cycle is the exhaust stroke. As the piston
approaches the end of the power stroke, the exhaust valve opens.
Pressure in the cylinder causes the exhaust gases to rush past the valve
and into the exhaust system. The piston moves up the cylinder, pushing
most of the remaining exhaust gases from the cylinder. As the piston
nears the top of this stroke, the exhaust valve begins to close as the
intake valve begins to open.
The exhaust stroke completes the combustion process. The opening of the
intake valve signals the beginning of a new cycle. This cycle occurs in
every cylinder and will be repeated as long as the engine is running.
All engines are given a number that represents their size or volume.
This number is referred to as engine displacement. It is usually
measured in cubic inches, cubic centimeters, or liters.
Volume Bore Stroke
Engine displacement is determined by first calculating the volume of one
cylinder. "Volume" is the amount of air/fuel mixture that is
needed to fill the cylinder. It is determined by the cylinder bore and
stroke. "Bore" refers to the diameter of a cylinder.
"Stroke" refers to the length of the piston travel between
top-dead-center and bottom-dead-center. This volume, multiplied by the
number of cylinders, determines the size of the engine, or displacement.
Units Of Measure
Prior to the early 70's, the displacement of an engine was measured in
cubic inches (an English measurement representing volume). However, as
the U.S. auto industry began to enter the international market, engine
displacement began to appear with metric measurements. Today, most
engines are measured in liters, a metric measurement representing
volume. The above chart will help you to convert cubic inches to
liters.
Compression Ratio
In describing an engine, you will often hear the compression ratio
mentioned. Compression ratio is the volume in one cylinder with the
piston at bottom-dead-center, divided by the volume with the piston at
top-dead-center. In other words, it's the amount that the air/fuel
mixture is squeezed or compressed in one cylinder. Compressing the
air/fuel mixture is very important for developing power. The greater the
compression, the more pressure on the piston when the fuel mixture
burns. The normal compression ratio for a gasoline engine is
approximately 9:1.
Structural Support
The engine block is the foundation of the engine. It provides structural
support to the other components. Notice that nearly all of the engine
parts are either contained inside it or attached to it. The block
consists of:
| Cylinder bores for the pistons
| Water passages for cooling the cylinders
| Oil passages for reducing friction, heat and wear of engine parts
| Mounting surfaces for the camshaft, crankshaft, cylinder head,
transmission, engine mounts and various other engine components |
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The camshaft may or may not be part of the engine block. Its location is
determined by the engine's configuration.
Construction
The block is cast in one piece and is usually made of iron. The word
"cast" refers to how the block is made. Casting transforms
molten metal into a particular shape by pouring or pressing it into a
mold. This molded piece is then machined so that all of the parts fit
together properly.
Piston
The pistons are located in the engine block -- one piston for every
cylinder. The piston is a cylindrical metal plug that moves up and down
in a cylinder bore. The piston forms the lower portion of the combustion
chamber and receives power from the burning air/fuel mixture.
The operation of a piston is fairly simple. After the air/fuel mixture
enters the combustion chamber, it is ignited. The burning fuel causes
the gases to expand, greatly increasing the pressure within the
combustion chamber. This pressure pushes against the top of the piston,
sending it down into the cylinder. The downward motion of the piston is
the mechanical force that is used to perform work.
Piston Rings
Piston rings are round, split metal rings that are the contact surfaces
between the piston and the cylinder wall. The rings, usually three per
piston, are placed in grooves on the piston and must perform three
crucial functions. They are:
| To seal the lower portion of the combustion chamber to increase
compression
| To scrape excess oil from the cylinder wall
| To transfer heat from the piston to the cylinder wall |
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If these functions are not performed properly, the engine's overall
performance will be severely affected.
Connecting Rods
Connecting rods are used to transmit the pressure applied from the
piston to the crankshaft. The rod must be very strong. It has to
withstand the tremendous force that is generated from the pressure of
the burning air/fuel mixture.
Piston Pin
The upper part of the rod (the small end) is connected to the piston
with a large steel pin. This pin is called the piston pin, also known as
the wrist pin. This pin allows the rod to transfer vertical (up and
down) piston motion to rotary motion via the crankshaft.
Connecting Rod Cap
The larger end of the rod is used to attach the connecting rod to the
crankshaft. This end consists of two pieces. The upper half is part of
the rod. The lower half, called the rod cap, is used to bolt the rod to
the crankshaft. The connecting rod and its cap are manufactured as a
unit and must always be kept together. Bearings are used in both ends of
the rod which allow it to move freely.
Crankshaft
The crankshaft is used to change the up-and-down motion of the piston
into a turning or rotating force. This force is then used to drive the
wheels of the vehicle.
The operation of a crankshaft is very simple. Its principal parts are
the shaft and crankpins. The crankpins, are the bearing surfaces to
which the connecting rods are attached. Each piston in the engine is
fitted to a crankpin.
Main Bearing Caps
The crankshaft is mounted to the bottom of the engine block by the main
bearing caps. The caps contain bearings which allow the crankshaft to
rotate freely. They also provide enough support to withstand the force
of the pistons.
Flywheel
Power impulses, caused by igniting the air/fuel mixture in the
combustion chamber of each cylinder, can cause the crankshaft to make
sudden movements resulting in a rough running engine. The flywheel
enables the crankshaft to make a smooth transition from one powerstroke
to the next.
Vibration Damper
The vibration damper, also known as a harmonic balancer, is another
device used to smooth out the power impulses of the engine. It is
mounted to the crankshaft (opposite the flywheel) and consists of a
small inertia ring and a counterweight.
As the crankshaft speeds up or slows down, the rubber insert gives
slightly. This causes the counterweight to oppose any sudden
movements. The back-and-forth movement of the crankshaft is
counterbalanced by the back-and-forth movement of the vibration
damper.
The cylinder head must perform a number of functions. These include:
| Sealing the tops of the cylinders
| Providing the spark plugs access to the combustion chamber
| Mounting for the valve train components
| Providing ports, seats, and guides for the intake and exhaust
valves
| Supporting the intake and exhaust manifolds |
| | | |
Construction
The construction of a typical four-cylinder engine head is shown at the
top of the page. The cylinder head is made of cast iron or aluminum and
is a structural member of the engine. The intake and exhaust manifolds
are mounted to the sides of the head. The top part of the head is
machined to accommodate most of the valve train components.
Combustion Chamber
When the head is placed upside down, you will notice several small,
recessed areas. Each recessed area is a combustion chamber. This can be
defined as the area above the piston where the burning of the air/fuel
mixture occurs. Each combustion chamber contains an intake valve, an
exhaust valve, and a spark plug. The valves control the flow of the
air/fuel mixture and exhaust gases to and from the combustion chamber.
The spark plugs ignite the air/fuel mixture.
Controlling Combustion
The intake of the air/fuel mixture and the exhaust of burned gasses must
be controlled for proper engine operation. This function is carried out
by the components associated with the engine's cylinder head. These
components are more commonly referred to as the valve train -- the
valves and their related parts.
Most of the components in the valve train are located in the cylinder
head. On the overhead cam engine (OHC), these components include the
valves, valve seats, valve guides, valve springs, rocker arms, and
camshaft. On the overhead valve engine (OHV), the camshaft is located in
the engine block and, in addition to the above components, the camshaft
requires the use of lifters and push rods to open the valves.
Head Gasket
The head is mounted on top of the engine block. The head must be
tightly sealed to contain the high pressure of the combustion. To do
this, the head gasket, is placed between the cylinder head and the
engine block.
Some vehicles are equipped with diesel engines. They are internal
combustion engines and usually operate on the four-stroke principle.
They are unlike gasoline-powered engines in several ways:
| They use diesel fuel instead of gasoline.
| They do not use spark plugs. The diesel fuel is ignited by the
heat of very high compression. |
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Diesel engines ignite the air/fuel mixture by increasing the temperature
of the air in the cylinder. This is accomplished by compressing the air
tightly and then introducing the fuel at the appropriate time (near the
end of the compression stroke). The fuel mixes with the "hot"
compressed air and ignites almost instantly.
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INSTALLATION
INSTRUCTIONS
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Break-In
Procedures
Failure to follow break-in procedures voids warranty.
Warranty does not cover installation of a wrong engine, or
a failure which occurs as a result of installation errors.
| Before
Installation |
| 1. |
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Determine
cause of failure of original engine and correct
before proceeding. |
| 2. |
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Compare
the remanufactured engine to the old engine. Check
location and size of mounting holes, dipstick
tube, crank pilot hole, etc. |
| 3. |
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Compare
new manifold gaskets to old manifold gaskets. |
| 4. |
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Clean
the oil pan, front cover, valve covers, etc. |
| 5. |
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Check
for foreign material in the intake manifold. |
| 6. |
|
Check
radiator condition. Have radiator rodded out or
replaced if necessary. |
| 7. |
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Check
oil pump drive, motor mounts, fuel pump, water
pump, fan belts, radiator hose, heater hose and
radiator pressure cap. Replace thermostat. |
| 8. |
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Clean
air cleaner housing and replace element. |
| 9. |
|
Check
engine accessories. |
| 10. |
|
Check
crankshaft pulley. |
| 11. |
|
Check
the exhaust thermostat control (heat riser). Be
sure exhaust flow is not restricted. Check
catalytic converter. |
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| During
Installation |
| 1. |
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If
installing Short Block, check condition of old
head(s). |
| 2. |
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Properly
seat the distributor. |
| 3. |
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Adjust
the clutch linkage. |
| 4. |
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Torque
all cylinder head bolts, or nuts to factory
specifications, and adjust valves. Repeat at 500
miles. |
| 5. |
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Replace
transmission filter. Check transmission cooler
lines. |
| 6. |
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Replace
PCV valve and hoses. |
| 7. |
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Service
ignition or fuel injection systems. |
| 8. |
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Replace
spark plugs. |
| 9. |
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Check
wiring for breaks and cracks. |
| 10. |
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Replace
oil filter. Clean or replace oil cooler and lines. |
| 11. |
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Check
the EGR valve, emission system components, and any
computer sensors to be sure they are operating
correctly. |
| 12. |
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Properly
torque flywheel to crankshaft and check that the
bolts are not bottoming against the block. Use
sealer on bolts that access crankcase. Do not use
an impact wrench on crankshafts with a full circle
seal. Be sure to use any spacer found on core. |
| 13. |
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Fill
the radiator with a coolant/water mix (add a good
sealer with rust inhibitor). Fill the crankcase
with new oil. |
| 14. |
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Prime
the oil pump and lines with an auxiliary pump
before starting engine. If using an air pressure
tank, be sure it does not run out of oil and blow
air through the lines. |
| 15. |
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Check
the starter, battery cables, etc. |
| 16. |
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Always
replace oil pump pick up tube with a new one. |
| 17. |
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Never
start an engine without first getting an oil
pressure reading on a manual gauge. |
| 18. |
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Check
carefully for any other potential external causes
of damage to the unit. |
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| Recommend
Break-In Procedures |
| 1. |
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Never
add cold water to the cooling system while the
engine is running. Allow the engine to run at
normal operating temperature. |
| 2. |
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Start
engine and run at a fast idle, approximately 1500
RPM, and check oil pressure. Run the engine for 30
minutes even though the coolant may rise to
operating temperature in a few minutes. Adjust
valves, carburetor and ignition timing. If the
coolant should "boil over", stop engine
and allow to cool. Correct any faulty running
conditions immediately. |
| 3. |
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Check
all manifolds for fluid and air leaks. |
| 4. |
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Stop
the engine and retorque head and manifold.
Readjust valves if necessary. |
| 5. |
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Start
engine again and make a test run on the road at 30
MPH in "drive" range or select proper
gears for standard transmission. Periodically open
throttle wide and accelerate to 50 MPH and
decelerate rapidly. Repeat this procedure at least
10 times. For a large truck or industrial engine,
accelerate in intermediate gears as above. |
| 6. |
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Drive
normally but not at continuous high speeds for the
first 500 miles. Change oil after 500 miles.
Caution the driver against "lugging." |
| 7. |
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Industrial
Engines: Follow above instructions and operate
under partial loads for several hours. Change oil
after 20 hours of operation. |
| 8. |
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After
500 miles of service, retorque cylinder heads and
manifolds to proper specifications. Readjust
valves. |
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| Break-In
Lubricant Recommendations |
| Follow
the recommendation of the vehicle manufacturer for
the proper viscosity and type of oil to be used.
Synthetic oil is only recommended after 5,000
miles of operation. We do not recommend
"Slick 50" or other "Teflon"
based additives. Use only motor oil unless
otherwise instructed by a warranty representative. |
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| Transmission
Translation Procedures |
Failure
to follow break-in procedures voids warranty.
Warranty does no cover installation of a wrong
engine, or a failure which occurs as a result of
installation errors. All vehicles must be properly
scanned for Diagnostic Trouble Codes before as
well as after installation. Not only will this
check all the electrical components, but it will
also tell you if the components that make the
automatic transmission function are in good
working order.
Some units require T.V. adjustment/setup to be
done with a pressure gauge
Units that use a cable (mechanical) linkage must
be set up with a pressure gauge. Check for proper
mechanical operation. Check for specific
instructions supplied with the unit.
Carefully inspect all wiring harnesses
Loose terminals and corrosion can cause your
remanufactured transmission to fail. Carefully
inspect all connectors for loose or bent pins. Use
an electrical contact cleaner to clean all
connections. Make sure all retainer clips are not
broken and are holding properly.
Transmission Oil Coolers must be flushed
according to O.E.M. specifications
Your remanufactured transmission will fail if all
contaminants from the previous failure are not
flushed from the system.. All transmission coolers
must be forward and reverse flushed. Any debris
left in the cooling system will cause premature
transmission failure that is not covered under
your warranty. Some coolers are not flushable and
must be replaced. Check your installation packet
for any further applicable information.
Check your Universal Joints, Driveshaft Yokes
and Axle Shafts
Bad universal joints can cause driveline
vibrations and premature bearing/bushing failure
to the transmission. FWD transaxle’s that have
any differential failure will damage the axle
shaft in most cases. Inspect very carefully the
ends that go into the transaxle.
Check fluid levels and for Proper Fluid Types
Make sure you are filling your unit with the
proper type of fluid. Check the furnished
installation sheet for any requirements on fluid
type or filling/checking procedures.
Check your Accessories
Your remanufactured transmission does not come
with any accessories, check all cooler lines,
engine and transmission mounts, TPS, VSS, throttle
cables, etc. These accessories can have a big
influence on how your transmission works, so give
them a look. All needed O-rings & seals should
have been furnished with your unit. Make sure and
change them to prevent any leaks.
Flex Plates, Dowel Pins & Crank Pilots
Check your flexplate to make sure it is not
cracked or the converter mounting pads are not
worn out. Crank pilot holes must be free from
debris. Put a small amount of grease in the pilot
to insure the converter slides into place
properly. Every automatic transmission must have 2
dowel pins in the back of the engine for proper
centerline alignment. If dowel pins are not in
perfect condition or are missing, the unit will
fail before the car drives home. |
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