MTB600
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Mechanic’s Tips
MT(B) 600
Series Transmissions
MT1357EN
Mechanic’s
Tips
Allison Transmission
MT 640, MT 643, MTB 643(R),
MT 644, MT 647, MTB 647,
MT 650, MT 653DR, MTB 653DR,
MT 654CR, MTB 654CR
MT1357EN
Division of General Motors Corporation
P.O. Box 894 Indianapolis, Indiana 46206-0894
Printed in U.S.A. Copyright © 1997 General Motors Corp.
July, 1997
Revised 199906
WARNINGS, CAUTIONS, AND NOTES
IT IS YOUR RESPONSIBILITY to be completely familiar with the warnings
and cautions described in this handbook. It is, however, important to understand that
these warnings and cautions are not exhaustive. Allison Transmission could not
possibly know, evaluate, and advise the service trade of all conceivable ways in
which service might be done or of the possible hazardous consequences of each
way. Consequently, Allison Transmission has not undertaken any such broad
evaluation. Accordingly, ANYONE WHO USES A SERVICE PROCEDURE OR
TOOL WHICH IS NOT RECOMMENDED BY ALLISON TRANSMISSION
MUST first be thoroughly satisfied that neither personal safety nor equipment safety
will be jeopardized by the service methods selected.
Proper service and repair is important to the safe, reliable operation of the
equipment. The service procedures recommended by Allison Transmission and
described in this handbook are effective methods for performing service operations.
Some of these service operations require the use of tools specially designed for
the purpose. The special tools should be used when and as recommended.
Three types of headings are used in this manual to attract your attention. These
warnings and cautions advise of specific methods or actions that can result in
personal injury, damage to the equipment, or cause the equipment to become unsafe.
WARNING:
etc., if not correctly followed, could result in personal injury or loss of life.
CAUTION:
etc., if not strictly observed, could result in damage to or destruction of
equipment.
NOTE:
essential to highlight.
A warning is used when an operating procedure, practice,
A caution is used when an operating procedure, practice,
A note is used when an operating procedure, practice, etc., is
ii
TABLE OF CONTENTS
Paragraph Description Page
Section I PREVENTIVE MAINTENANCE
1–1 Periodic Inspection and Care . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1–2 Importance of Proper Fluid Level . . . . . . . . . . . . . . . . . . . . . . . 1
1–3 Dipstick Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1–4 Fluid Check Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1–5 Keeping Fluid Clean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1–6 Recommended Automatic Transmission Fluid
and Viscosity Grade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1–7 Fluid and Filter Change Intervals. . . . . . . . . . . . . . . . . . . . . . . . 6
1–8 Fluid and Filter Change Procedure . . . . . . . . . . . . . . . . . . . . . . 8
1–9 Fluid Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1–10 Auxiliary Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1–11 Breather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1–12 Transmission Stall Test and Neutral
Cool–Down Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Section II REMOVING TRANSMISSION
2–1 Draining Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2–2 Disconnecting Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2–3 Uncoupling From Engine And Driveline. . . . . . . . . . . . . . . . . 16
2–4 Removing Mounting Bolts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2–5 Removing Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2–6 Repair Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Section III PREPARING TRANSMISSION FOR INSTALLATION
3–1 Checking Input Components . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3–2 Checking Torque Converter Position. . . . . . . . . . . . . . . . . . . . 20
3–3 Installing Parking Brake and Output Flange . . . . . . . . . . . . . . 21
3–4 Installing Shift Selector Lever . . . . . . . . . . . . . . . . . . . . . . . . . 22
3–5 Installing Power Takeoff (PTO). . . . . . . . . . . . . . . . . . . . . . . . 23
3–6 Installing Shift Modulation Control. . . . . . . . . . . . . . . . . . . . . 25
3–7 Installing Fill Tube and Drain Plug . . . . . . . . . . . . . . . . . . . . . 25
3–8 Installing Neutral Start and Reverse Signal Switches . . . . . . . 26
3–9 Checking Breather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
iii
Paragraph Description Page
Section IV PREPARING VEHICLE FOR TRANSMISSION
INSTALLATION
4–1 Checking Flexplate, Engine Features. . . . . . . . . . . . . . . . . . . . 28
4–2 Checking Chassis, Driveline . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4–3 Checking Cooler, Tubes, Hoses, Fittings. . . . . . . . . . . . . . . . . 33
4–4 Checking Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4–5 Mounting Adapter or Spacer . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Section V INSTALLING TRANSMISSION INTO VEHICLE
5–1 Handling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5–2 Coupling to Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5–3 Mounting Output Retarder. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5–4 Installing Transmission Mounting Components . . . . . . . . . . . 36
5–5 Coupling to Driveline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5–6 Connecting Cooler, Vacuum Lines, Air Lines. . . . . . . . . . . . . 36
5–7 Connecting Shift Selector Control. . . . . . . . . . . . . . . . . . . . . . 37
5–8 Installing Vacuum or Air Modulator Control . . . . . . . . . . . . . 38
5–9 Installing, Adjusting Mechanical Modulator Control . . . . . . . 39
5–10 Connecting Power Takeoff Controls . . . . . . . . . . . . . . . . . . . . 40
5–11 Connecting Parking Brake Control . . . . . . . . . . . . . . . . . . . . . 40
5–12 Connecting Speedometer Drive . . . . . . . . . . . . . . . . . . . . . . . . 40
5–13 Filling the Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Section VI CHECKS AND ADJUSTMENT
6–1 Installation Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6–2 Road Test and Vehicle Operation Checklist . . . . . . . . . . . . . . 44
Section VII CUSTOMER SERVICE
7–1 Owner Assistance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7–2 Service Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
iv
PREFACE
This handbook is a ready reference for the mechanic removing, installing, or maintaining MT(B) 600 Series Automatic Transmissions. All features of both the vehicle
and transmission that become involved in the installation procedures are discussed.
The information presented will help the mechanic to remove, install, and maintain the
transmission in a manner that assures satisfactory operation and long service life.
TRADEMARKS USED
DEXRON-III
®
Loctite
Teflon
is a registered trademark of the Loctite Corporation
®
is a registered trademark of the DuPont Corporation
®
is a registered trademark of General Motors Corporation
v
vi
Model MT 643 Transmission — Right-Front View
Model MT 653 Transmission — Right-Front View
Model MTB 644/647 Transmission — Right-Front View
PREVENTIVE
MAINTENANCE
S
I
ECTION
1–1. PERIODIC INSPECTION AND CARE
Clean and inspect the exterior of the transmission at regular intervals. The severity
of service and operating conditions will determine the frequency of such
inspections. Inspect the transmission for the following items:
•
Loose bolts (transmission and mounting components)
•
Fluid leaks (correct immediately)
•
Shift linkage freely positioned by transmission detent
•
Full (and ease of) movement of mechanical modulator linkage
•
Leaks in the vacuum or air line and modulator
•
Damaged or loose fluid lines
•
Worn or frayed electrical connections
•
Worn, out-of-phase driveline U-joints and slip fittings
•
Loose or missing speedometer cable and fittings
•
Damaged PTO linkage and driveline
Check transmission fluid regularly . Once consistent daily hot le vel checks ha ve been
established, and daily inspection shows no sign of transmission leakage, less
frequent checks can be made.
1–2. IMPORTANCE OF PROPER FLUID LEVEL
Because the transmission fluid cools, lubricates, and transmits hydraulic
power, it is important that the proper fluid level be maintained at all
times. If the fluid level is too low, the input pump will draw air into the
system and the converter and clutches will not receive an adequate
supply of fluid. If the level is too high, clutch rotation will aerate the
fluid, the transmission will overheat, and fluid may be expelled through
the breather or dipstick tube. Check the transmission fluid for changes in
viscosity or color. Thin, milky fluid indicates aeration is occurring due
to improper fluid, incorrect fluid level, or a defectiv e or missing sealring
on the intake pipe of the internal filter.
1
1–3. DIPSTICK MARKINGS
Earlier models use a dipstick marked FULL and ADD. Later models use a dipstick
marked REF FILL (COLD RUN) and HOT RUN. Figure 1–1 shows typical dipstick
markings for MT 600 Series transmissions. Figure 1–2 illustrates the marks in
relation to the transmission.
NOTE:
The ADD and FULL dimensions on earlier dipsticks coincide
with the HOT RUN band dimension on later dipsticks. If desired, the
dipstick on earlier models can be recalibrated to show HOT RUN and
REF FILL (COLD RUN).
CHECK IN NEUTRAL
AT IDLE
TRANSMISSION
OIL PAN
SPLITLINE
HOT RUN
(19.0 mm)
0.75"
REF
FILL
4.34 in.
OIL PAN
1.50"
(38.0 mm)
(45.7 mm)
CHECK IN NEUTRAL AT IDLE
0.75"
(19.0 mm)
HOT RUN
1.80"
1.50"
(38.0 mm)
REF
FILL
CHECK IN NEUTRAL AT IDLE
2.55"
(64.8 mm)
2.22"
(57.1 mm)
HOT RUN
0.75"
(19.0 mm)
1.50"
(38.0 mm)
5.10 in.
OIL PAN
Figure 1–1. Typical Dipstick Markings
2
7 in.
OIL PAN
V03240
0.75"
(19 mm)
FULL
ADD
1.50"
(38 mm)
MT 643 / 653
Figure 1–2. How Fluid Levels Are Established
1–4. FLUID CHECK PROCEDURE
WARNING: To help avoid injury and property damage caused by
sudden and unexpected vehicle movement, do not perform
maintenance or service procedures until you:
• Put the transmission in N (Neutral).
• Set the parking brake and service brakes, and make sure they are
properly engaged.
• Chock the wheels and take any other steps necessary to keep the
vehicle from moving.
2.22"
(57 mm)
2.55"
(65 mm)
TOP OF
OIL PAN
HOT RUN
REF FILL
V03241
CAUTION: Dirt or foreign matter must not be permitted to enter the
fluid system. It can cause valves to stick, cause undue wear of
transmission parts, or clog passages.
Always check the fluid level a minimum of two times. Consistency is important in
maintaining accuracy. If inconsistent readings persist, check the transmission
breather and the vent hole in the dipstick fill tube to ensure they are clean and free of
debris. The vent hole is located on the underside of the fill tube just below the seal
of the dipstick cap.
3
•
•
•
•
•
•
Check the fluid level by the following procedures and record any abnormal fluid
level, milky appearance, or any trace of coolant in the fluid on your maintenance
records.
a.
Cold Check
NOTE: The only purpose of the Cold Check is to determine if the
transmission has enough fluid to be safely operated until a Hot Check
can be made.
Park the vehicle on a level surface, set the parking brake and/or emergency
brakes, and chock the vehicle wheels.
Run the engine at 1000–1500 rpm for one minute to purge air from the
system. Return engine to idle, then shift to D (Drive) and then to R (Reverse)
to fill the hydraulic circuits with fluid. Then, shift to N (Neutral) and allow the
engine to idle (500–800 rpm). The sump temperature should be between
60–120°F (16–49°C).
CAUTION: The fluid level rises as sump temperature increases. DO
NOT fill above the COLD RUN band if the transmission fluid is
below normal operating temperature.
Clean around the end of the fill tube before removing the dipstick. Wipe the
dipstick clean and check the fluid level. If the fluid on the dipstick is within
the REF FILL (COLD RUN) band, the level is satisfactory for operating the
transmission until the fluid is hot enough to perform a HOT R UN check. If the
fluid level is not within the REF FILL (COLD RUN) band, add or drain fluid
as necessary to bring the level to the middle of the REF FILL (COLD RUN)
band.
Perform a hot check at the first opportunity after the normal operating sump
temperature 160–200°F (71–93°C) is reached.
b.
Hot Check
NOTE: The fluid level rises as the temperature increases. To ensure
an accurate check, operate the transmission until the sump fluid
temperature is 160–200°F (71–93°C) or converter-out temperature is
180–220°F (82–104°C).
Park the vehicle on a level surface and shift to N (Neutral). Set the parking
brake and/or emergency brakes and chock the vehicle wheels. Allow the
engine to idle (500–800 rpm).
Clean around the end of the fill tube before removing the dipstick. Wipe
the dipstick clean and check the fluid level. The safe operating range is any
4
•
•
level within the HOT RUN band on the dipstick. If the level is not within this
band, add or drain fluid as necessary to bring the level to the top of the
HOT RUN band.
1–5. KEEPING FLUID CLEAN
CAUTION: Containers or fillers that have been used to handle any
antifreeze or engine coolant solution must not be used for
transmission fluid. Antifreeze and coolant solutions contain ethylene
glycol which, if introduced into the transmission, can cause the clutch
plates to fail.
It is absolutely necessary that the fluid put into the transmission be clean. Fluid must
be handled in clean containers, fillers, etc., to prevent foreign material from entering
the transmission. Lay dipstick in a clean place while filling the transmission.
1–6. RECOMMENDED AUTOMATIC TRANSMISSION FLUID
AND VISCOSITY GRADE
RECOMMENDED AUTOMATIC TRANSMISSION FLUID AND
VISCOSITY GRADE — NON-MT 643R TRANSMISSIONS
Hydraulic fluids (oils) used in the transmission are important influences on
transmission performance, reliability, and durability.
The following transmission fluid and viscosity grades are recommended.
— DEXRON
®
-III fluids for standard duty, on-highway applications
— Type C-4 fluids (Allison approved SAE 10W or SAE 30) for severe duty
and off-highway applications
— Type C-4 SAE 30 for all applications where the ambient temperature is
consistently above 95°F (35°C)
— Type C-4 SAE 30 for dropboxes
Some DEXRON
®
-III fluids are also qualified as Type C-4 fluids. To
ensure the fluid is qualified for use in Allison transmissions, check for a
DEXRON
®
-III or C-4 fluid license, or approval numbers on the container, or
consult the lubricant manufacturer. Consult your Allison Transmission dealer
or distributor before using other fluid types; fluid types such as Type F, and
universal farm fluids may or may not be properly qualified for use in your
Allison transmission.
CAUTION: Disregarding minimum fluid temperature limits can
result in transmission malfunction or reduced transmission life.
5
•
N
•
•
•
•
When choosing the optimum viscosity grade of fluid to use, duty cycle,
preheat capabilities, and/or geographical location must be taken into
consideration. Table 1–1 lists the minimum fluid temperatures at which the
transmission may be safely operated in a forward or reverse range. Operation
at ambient temperatures lower than those shown will require preheating with
auxiliary heating equipment or by running the vehicle with the transmission in
(Neutral) for a minimum of 20 minutes before attempting range operation.
RECOMMENDED AUT OMA TIC TRANSMISSION FLUID AND
VISCOSITY GRADE — MT 643R TRANSMISSIONS
Due to the added heat load from the input retarder, MT 643R transmissions
require special fluid considerations. The approved fluids list is more restricti ve
than for non-retarder MT 643R transmissions. Also, the fluid change interv als
are shorter than for non-retarder MT 643R transmissions.
Only high quality, hea vy duty diesel engine oils that are appro v ed Allison C-4
fluids with a viscosity of either SAE 30 or SAE 15W-40 are recommended for
use in MT 643R transmissions. For specific name brands, contact the local
Allison Transmission Regional Office.
Refer to Table 1–1 for minimum fluid temperatures at which the transmission
may be safely operated with various fluids. Operation at ambient temperatures
lower than those shown will require preheating with auxiliary heating
equipment or by running the vehicle with the transmission in N (Neutral) for a
minimum of 20 minutes before attempting range operation.
Table 1–1. Transmission Fluid Operating Temperature Requirements
Viscosity Grade
Ambient T emperatur e Below Which Preheat
Is Required
Fahrenheit Celsius
SAE 0W-20 (Arctic) –31 –35
DEXRON
®
-III
–22 –30
SAE 10W –4 –20
SAE 15W-40 5 –15
SAE 30 32 0
SAE 40 50 10
1–7. FLUID AND FILTER CHANGE INTERVALS
Fluid and filter change frequencies are determined as follows.
Table 1–2 is a general guide. The fluid must be changed whenever
there is evidence of dirt or high temperature indicated by
6
•
discoloration or strong odor. More frequent changes may be required
when operations are subject to high levels of contamination or
overheating.
Fluid change intervals can be optimized by monitoring fluid oxidation
according to the tests and limits in the Fluid Contamination section of this
manual.
Table 1–2. Fluid and Filter Change Intervals
Transmission
Application
MT 600 Series
(On-Highway,
Non-MT 643R)
MT 643R After first 5000
MT 600 Series
(Off-Highway)
* Whichever occurs first.
** An Allison high-efficiency filter may be used until the Change Filter light indicates it is
contaminated or until it has been in use for 3 years, whichever occurs first. No mileage restrictions
apply.
Fluid Change
25,000 miles
(40 000 km)
or 12 months*
miles (8000 km)
then at 20,000
miles (32 000
km) or 12
months*
1000 hours
maximum or
12 months*
Internal Sump
Filter
Paper Filter:
25,000 miles
(40 000 km) or
12 months*
Stainless Steel
Screen:
At overhaul
Paper Filter:
At every other
fluid change
Stainless Steel
Screen:
At overhaul
Paper Filter:
1000 hours
maximum or 12
months*
Stainless Steel
Screen:
At overhaul
Governor
Filter
25,000 miles
(40 000 km)
or 12 months*
20,000 miles
(32 000 km) or
12 months*
1000 hours
maximum or
12 months*
External
Auxiliary
Filters**
After first 5000
miles (8 000 km)
and at normal fluid
change intervals,
thereafter*
After first 5000
miles (8000 km)
then at each fluid
change, thereafter
After first 500
hours and at
normal oil change
intervals,
thereafter*
A stainless steel screen sump filter is available for all later model MT 600 Series
transmissions except the MT(B) 654CR. This filter does not require replacement at
the regular fluid change intervals, but transmissions equipped with a sump screen
must have an auxiliary filter in the external transmission cooling circuit. Refer to
Service Information Letter (SIL) 6-TR-96 (latest revision).
7
•
•
•
•
•
•
1–8. FLUID AND FILTER CHANGE PROCEDURE
a. Drain
The transmission should be at operating temperature to assist
draining.
Remove the drain plug from the pan. In earlier models without a drain plug,
remove the fill tube.
Examine the drained fluid for evidence of contamination (refer to
Paragraph 1–9).
Remove the pan and gasket. Discard the gasket. Remove the washer head
screw that retains the filter. Remove the filter and filter tube. Discard the filter
(if being replaced) and the filter tube sealring. Clean the pan.
NOTE: Transmissions equipped with a stainless steel screen sump
filter or a 7.0 inch (180 mm) pan do not require pan removal. Refer to
Service Manual SM1317EN or SM1546EN for specific procedures.
Install a new governor feed filter at the rear of the transmission. Refer to the
latest revision of Service Manual SM1317EN or SM1546EN for the exact
location.
Install a new filter if required. Insert a new sealring onto the filter tube. Install
the filter tube and filter into the main housing. Install the pan and pan gasket if
removed. Tighten the pan screws to 10–15 lb ft (14–20 N·m).
•
•
•
•
•
NOTE: To prevent leakage, pan washer head screws must retain
a 5 lb ft (7 N·m) minimum torque after gasket sets.
Install the drain plug into the pan and tighten it to 15–20 lb ft (20–27 N·m). If
the fill tube was removed (earlier models), install the fill tube and tighten the
fill tube fitting in the pan boss to the torque shown in Paragraph 6–1.
If an external auxiliary filter is present, replace the filter element. Refer to
Table 1–2 for replacement intervals.
b.
Fill
Refill the transmission. (Refer to Paragraph 1–6 and Table 1–3.)
The refill amount is less than the initial fill because some of the fluid remains
in the external circuits and transmission cavities.
Check the fluid level as outlined in Paragraph 1–4.
8
9
Table 1–3. Transmission Fluid Refill Capacities
Pan T ype Quantity
4.3 inches (110 mm) 12 U.S. qt. (11 liters)*
5.1 inches (130 mm) 15 U.S. qt. (14 liters)*
7.0 inches (180 mm) 17 U.S. qt. (16 liters)*
* The amount of transmission fluid shown does not include the amount required to fill the
external circuits.
1–9. FLUID CONTAMINATION
a.
Examine at Fluid Change
At each fluid change, examine the fluid which is drained for evidence of dirt or
engine coolant (water). A normal amount of condensation will emulsify in the fluid
during operation of the transmission. However, if there is evidence of coolant, check
the cooler (heat exchanger) for leakage between the cooler and fluid areas. Fluid in
the coolant side of the cooler (heat exchanger) is another sign of leakage. This,
however, may indicate leakage from the engine oil system.
Metal Particles
b.
CAUTION: If excessive metal contamination has occurred,
replacement of the cooler and inspection of all bearings within the
transmission is recommended.
Metal particles in the fluid or on the magnetic drain plug (except for the minute
particles normally trapped in the filter) indicate damage has occurred in the
transmission. When these particles are found in the sump, the transmission must be
disassembled and closely inspected to find the source. Metal contamination requires
complete disassembly of the transmission and cleaning of all internal and external
circuits, cooler, and all other areas where the particles could lodge. (Refer to
Paragraph 1–10, Auxiliary Filter.)
c.
Coolant Leakage
If engine coolant leaks into the transmission hydraulic system, take immediate
action to prevent malfunction and possible serious damage. Completely
disassemble, inspect, and clean the transmission. Remove all traces of the coolant
and varnish deposits resulting from coolant contamination. Replace friction clutch
plates contaminated with ethylene glycol.
d.
Fluid Analysis
Transmission protection and fluid change intervals can be optimized by transmission
fluid analysis. Consult your local telephone directory for fluid analysis firms. Use
one fluid analysis firm as results from various firms cannot be accurately compared.
Refer to the Technicians’ Guide for Automatic T ransmission Fluid (GN2055EN) for
additional information.
To optimize transmission protection, the following is the minimum series of tests
required to properly monitor the condition of the transmission and transmission
fluid/filter system.
•
Wear Metals (ppm): Fe, Cu, Pb, Al
•
Additive and Contaminant Metals (ppm): Ba, B, Ca, Mg, P, Si, Na, Zn
•
Non-metal Contaminants: Fuel (% vol), Soot, (% wt), Water (% vol)
•
Viscosity (cSt) at 40˚C (ASTM D445)
•
Viscosity (cSt) at 100˚C (ASTM D445)
•
TAN (Total Acid Number) (ASTM D664)
•
Particle Counts (particles/ml) at >5, >10, >20, >30, and >40 microns
ppm = parts per million cSt = centiStokes ml = milliliter
10
To optimize fluid change intervals, monitor fluid oxidation per the tests and limits
shown in Table 1–4. A fluid is considered suitable for use if it meets all four limits
listed in the table, regardless of color or odor. If one of the limits is exceeded,
however, the fluid in the subject transmission should be sampled again immediately
to verify the exceeded limit. If verified, the fluid should be changed regardless of
time or mileage.
Table 1–4. Fluid Oxidation Measurement Limits
Condition Limit
Viscosity ± 25% Change From New Fluid
Carbonyl Absorbance
Total Acid Number (TAN)
Solids
* Carbonyl absorbance units/cm
** mg of KOH required to neutralize a g of fluid
+ 30* Change From New Fluid
+ 3.0** Change From New Fluid
2% By Volume Maximum
1–10. AUXILIARY FILTER
If a condition occurs that introduces debris into the transmission hydraulic system,
completely clean up the cooler and lines.
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