1973 OPEL 1900 manual transmission

7C- 541973 OPEL SERVICE MANUAL
Figure 7C-38 1 2 Shift Valve
To prevent a “hunting” condition of the shift valve,
modulator pressure supply to the second spool of
control valve is cut off as the shift valve opens line
pressure to the second clutch. The oil in this pocket
is exhausted out through the detent passage. An ad-
ditional force keeping the valve in an “upshifted”
position is obtained by line pressure acting on the
larger diameter second spool of the shift valve. Be-
cause of this, even though the governor pressure
might be maintained at a constant pressure after the
valve upshifts, a higher modulator pressure is re-
quired to cause the valve to downshift.
If the accelerator is depressed to the point where the
detent spring force is felt, the vacuum will drop and
the modulator pressure will increase. If the spring
force plus the modulator pressure acting against the
end spool of the shift control valve is great enough
to overcome the governor and line pressure acting on
the shift valve, a “part throttle” forced downshift
will occur. If not, the transmission will remain in the
higher gear.
If the accelerator is depressed through the detent, the
detent valve supplies detent regulator pressure to all
three spools of the shift control valve, a higher down-
shifting force is obtained as compared to the part
throttle condition. Because of this, a “through
detent” forced downshift can be obtained at a speed
higher than for the “part throttle” condition. How-
ever, there is still a limiting speed at which a
“through detent” forced downshift will occur.
If the selector lever is placed in “Manual Low”, line
pressure is supplied directly to the spring pocket
between the valves. Since line pressure can never be
less than governor pressure, the force established by
line pressure on the shift valve plus the spring forcewill move the shift valve to a downshifted position
regardless of car speed.
2 3
,Shift Valve and 3 - 2 Control Valve
The function and operation of the 2 3 Shift and
Shift Control Valves is the same as for the
I 2 valve
except as described below. See Figure
7C-39.The downshifted position establishes “second” gear,
and the upshifted position establishes “third” or
“high” gear.
~ZND CLUTCH*
-I.Figure
7C-39 2 3 Shift Valve and 3 2 Control Valve
Modulator pressure is supplied to the end spool of
the 2
- 3 control valve through the 3 - 2 control valve.
When the shift valve moves to the upshifted position,
line pressure is introduced to the third clutch circuit.
The third clutch circuit also directs pressure to the
end spool of the 3
- 2 control valve.
At light throttle conditions, third clutch pressure
acting on the end of the 3
- 2 control valve moves the
valve against the spring and the force established by
the modulator pressure. This exhausts the modulator
pressure from behind the end spool of the 2
- 3
control valve and the spring is the only remaining
force acting on the shift valve to produce a down-
shift. In this condition, it is not possible to obtain a
“part throttle” forced downshift.
If the accelerator is depressed far enough to cause a
substantial drop in vacuum, the increased modulator
pressure on the 3
- 2 control valve plus the spring will
overc,ome the force of the third clutch pressure. This
feeds modulator pressure back to the 2
- 3 control
valve and a “part throttle” forced downshift will
occur. As with the 1 2 shift valve, there is a limiting
speed at which this can occur.
When the selector lever is placed in “Second”, line
pressure is directed to the spring pocket between the
2
- 3 Shift and Shift Control Valves and the shift

AUTOMATIC TRANSMISSION7c- 55
valve will be held in downshifted, or second gear,
condition regardless of car speed.
Manual Low and Reverse Control Valve
As described in the text on “Mechanical Operation”,
the third clutch is applied in manual “Low” and in
“Reverse” to prevent a free wheeling condition. In
“Drive” range third gear, third clutch pressure is
also directed to the release side of the low servo (to
be covered later). This is the pressure which causes
the low band to release during a 2-3 upshift. How-
ever, in manual low, the band must remain applied
even though the third clutch is on.
The above conditions are achieved by routing third
clutch pressure to the release side of the low servo
through the manual low and reverse control valve.
See Figure 7C-40. In “Drive” range, the spring holds
the valve in its “bottomed” position and permits the
third clutch pressure to be directed to the servo re-
lease circuit.
_~RDSERVO RELEA
ILOW CONTROL
Figure 7C-40 Manual LOW
and Ftever~e Control Valve
When the selector lever is placed in manual “Low”,
line pressure is introduced between the manual low
and reverse control valves. This forces the low con-
trol valve over against the spring. In this position,
third clutch pressure is cut off from servo release and
servo release is opened to exhaust. The third clutch
exhaust passage is now open to detent regulator pres-
sure which applies the third clutch since the shift
valve is in the “downshifted” position. Because the
servo release passage is open to exhaust, the low band
will remain applied.
When the selector lever is placed in “Reverse,” line
pressure acts on the end of the reverse control valveand forces the low control valve into the same posi-
tion as in manual “Low”. This causes the third
clutch to be applied.
Boost Control Valve
To obtain the required pressure increase previously
described for “Second” “Low” and “Reverse”, line
pressure is introduced to the stepped area between
the two spools of the pressure regulator boost valve.
In “Second” or “Low”,
some means has to be prov-
ided to prevent the pressure to the boost valve from
being exhausted through the reverse passage. It is
also necessary to prevent reverse pressure from being
exhausted through the intermediate passage when in
“Reverse”.
The boost control valve consists of a steel ball in a
flow and pressure sensitive chamber. See Figure 7C-41. Where the reverse passage is pressurized. the
pressure and flow seat the ball against the intermedi-
ate passage and the pressure is directed to the boost
passage. In “Second” or manual “Low”, the ball is
seated against the reverse passage and the pressure is
directed to the boost passage.
t-INTERMEDIATE
7c.4,
I I
REVERSE:Figure 7C-4
1 Boost Control Valve
Low Speed Downshift Timing Valve
When the vehicle is coasting to a stop, and a
3-2downshift takes place, it is necessary to delay the
application of the band while the third clutch is
being released. This is accomplished by directing
the servo release pressure through the coast down-
shift timing valve. See Figure 7C-42.

a.Operation of Controls in Neutral Engine Running
Reverse Clutch ReleasedThird Clutch Released
Second Clutch ReleasedSprag LockedLow Band Released
Whenever the engine is running with the selector lever in Neutral, oil is pulled from the sump into the oil pump and is dispensed from the pump under preure.
The pressurized line oil if directed
to the priming valve which bleeds off the air. Line oil is directed to the vacuum modulator YBIYB, to the prexwre regulator valveand
to the manual veIve. The converter is fed through the pressure regulator MIYB. the return oil from the converter being directed through the coalerand back
into the transmisGon’s lubricating system.
Line oil directed
to the vacuum modulator valve becomes regulated to modulator oiland acts on the pressure regulator boosI YBCB. the IDW speed downshift timing
valve. the 1 2 accumulator MIYB. and the detent valve. The modulator oil passes through the detent valve to act 00 the I 2 shift control give. the 3 2 control
valve and the 2 3 shift control valve. Line oil pasres through the manual v&e. and is regulated et the detent preaure regulator valve before being directed to the
Reverseand Low control delve.Summary
The converter is filled. the clutches and
IDW band are released.The transmission is in Neutral.

e. Operation of Controls in Second Range Second Gear
Reverse Clutch
Re easedThird Clutch Released
Seconds Clutch AppliedLow Band Applied
Sprag Over Running
The
selector lever is moved to the Intermediate position an the quadrant. the manual valve is positioned to allow drive oil and Intermediate oilto pan through the valve. Intermediate oil is directed
to the pressure regulator boost control cavity, seating the check ball at the reverse passage.Intermediate oil is then directed to the pressure regulator valve downward to
increaSe the oil prepare in the circuit. At the same time. the inter.
mediate oil from the manual valve is directed lo the 2 3 shift valve train closing off the supply of third clutch oil in the circuit, which isexhausted
through the Reverse and Low control
valve.
SummaryWith third clutch oil exhausted. the third clutch is off, the second clutch is an, the low band
servo is applied. The transmission is in second
Range Second Gear.

9. Operation of Controls in Reverse
Reverse Clutch -Applied
Second Clutch Released
Sprag LockedThird Clutch. Applied
Low Band. Released
When the selector leer is moved to the Reverse position on the quadrant, the manual
valve ispositioned to allow Revert oil to pars through the manual
valve into the
Reverse oil passage. The reverse oil applies the reverse clutch. and a portion is directed to the priming valve which acts as a damper until the
line is filled. to effect a smooth and firm apply of the
reverss clutch. At the wne time, reverse oil is directed to the pressure regulator boost control valve
cavity to seat the check ball and prevent reverse oil pasring into the intermediate oil passage. It is then directed to the pressure regulator boast valve forcing
Reverse oil is also directed to act on the end of the
Reverse and Law control valve against the spring to allow detent regulated oil to pass through the valveto the 2 3 shift
valve. The detent regulated oil passes through the 2 3 shift valve and into the third clutch oil passages to apply the third clutch. The third
clutch oil
al= acts on the end of the 3 2 control valve against the spring and modulator oil pressure, clodng off the supply of modulator oil to the 2 3
shift control valve. Third clutch oil at the rwerse and low control valve is closed off from
parring through the valve. and into the servo releal~ parrage.Summary
The
reverse clutch is cm and the third clutch is on. The transmission is in Reverse Range.

DIAGNOSIS
SEQUENCE
1. Check and correct oil level. Refer to Specifications
for checking and refill procedures.
2. Check and correct vacuum line and fittings.
3. Check and correct manual linkage.
4. Road test car using all selective ranges, noting
when discrepancies in operation occur.
5. If engine performances indicates an engine tuneup
is required, this should be performed before road
testing is completed or transmission correction at-
tempted. Poor engine performance can result in
rough shifting or other malfunctions.
CHECKING PROCEDURESBefore diagnosis of any transmission complaint is
attempted, there must be an understanding of oil
checking procedure and what appearance the oil
should have. Many times a transmission malfunction
can be traced to low oil level, improper reading of
dipstick, or oil appearances; therefore, a careful anal-
ysis of the condition of oil and the level may elimi-
nate needless repairs.
When checking oil level in the Opel Three Speed
Automatic Transmission, the procedure outlined in
Specifications should be followed to obtain the most
accurate reading.
Also when the dipstick is removed, it should be noted
whether the oil is devoid of air bubbles or not. Oil
with air bubbles gives an indication of an air leak in
the suction lines, which can cause erractic operation
and slippage. Water in the oil imparts a milky, pink
cast to the oil and can cause spewing.
EXTERNAL OIL LEAKS
Determining source of oil leakBefore attempting to correct an oil leak, the actual
source of the leak must be determined. In many
cases, the source of the leak can be deceiving due to
“wind flow” around the engine and transmission.
The suspected area should be wiped clear of all oil
before inspecting for the source of the leak. Red dyeAUTOMATIC TRANSMISSION 7C- 81
is used in the transmission oil at the assembly plant
and will indicate if the oil leak is from the transmis-
sion.The use of a “Black Light” to locate the point at
which the oil is leaking is helpful. Comparing the oil
from the leak to that on the engine or transmission
dipstick, when viewed by Black Light, will determine
the source of the leak-engine or transmission.
Oil leaks around the engine and transmission are
generally carried toward the rear of the car by air
stream. For example, a transmission oil filler tube to
case leak will sometimes appear as a leak at the rear
of the transmission. In determining the source of a
leak, proceed as follows:
1. Degrease underside of transmission.
2. Road test to get unit at operating temperature.
3. Inspect for leak with engine running.
4. With engine off, check for oil leaks due to the
raised oil level caused by drain back.
Case Porosity RepairOpel Three-Speed Automatic Transmission external
oil leaks caused by case porosity can be successfully
repaired with the transmission in the car by using the
following recommended procedures:
1. Road test and bring the transmission to operating
temperature, approximately 180 degrees F.
2. Raise car on a hoist or jack stand, engine running,
and locate source of oil leak. Check for oil leaks in
low, drive, and reverse.
3. Shut engine off and thoroughly clean area to be
repaired with a suitable cleaning solvent and a
brush- air dry. A clean, dry soldering acid brush can
be used to clean the area and also to apply the epoxy
cement.
4. Using instructions of the manufacturer, mix a suf-
ficient amount of epoxy, BUICK Group 0.423, Part
No. 1360016, or equivalent, to make the repair. Ob-
serve cautions of manufacturer in handling.
5. While the transmission case is still HOT, apply the
epoxy to the area to be repaired. Make certain the
area to be repaired is fully covered.
6. Allow cement to cure for 3 hours before starting
engine.
7. Road test and check for leaks.

7C- 821973 OPEL SERVICE MANUALAUTOMATIC TRANSMISSION TROUBLE
DIAGNOSIS CHART
Condition
CEllE.e
Concerns Transmission Oil1. Low oil level.a) Oil coming out of oil tiller tube.
b) External oil leak.
c) Failed vacuum modulator.
2. Oil coming out of oil filler
tube.a) Oil level too high.
b) Coolant in transmission oil.
c) External vent clogged with mud.
d) Leak in oil pump suction circuit.
3. External oil leaks in the area
of the torque converter housing.a) Leaking torque converter.
b) Converter housing seal.
c) Sealing washers under converter
housing to case bolts.
d) Sealing washers under converter
housing to pump bolts.
e) Converter housing to case seal.
fj Loose attaching bolts on front of
transmission.
4. External oil leaks in the area
of transmission case and extension.a) Shifter shaft seal.
b) Extension seal.
c) Oil pan gasket.
d) Extension to case gasket.
e) Vacuum modulator gasket.
f) Drain plug gasket.
g) Cooler line fittings.
h) Oil tiller tube seal ring.
i) Detent cable seal ring.
j) Line pressure gauge connection.
5. Low oil pressure.a) Low oil level.
b) Clogged suction screen.
c) Leak in oil pump suction circuit.
d) Leak in oil pressure circuit.
e) Priming valve stuck.
t) Pressure regulator valve malfunction.
g) Sealing ball in valve body dropped out.
6. High oil pressure.a) Modulator vacuum line leaky orinteruupted.
b) Failed vacuum modulator.
c) Leak in any part of engine or
accessory vacuum system.
d) Pressure regulator valve malfunction.
7. Excessrive smoke coming from
exhaust.a) Failed vacuum modulator.
b) Oil from vent valve or leak on hot
exhaust pipe.

AUTOMATIC TRANSMISSION 7C- 83
ConditionCause
Starting
1. No starting in any driverange.a) Low oil level.
b) Clogged suction screen.
c) Manual valve linkage or inner trans-
mission selector lever disconnected.
d) Input shaft broken.e) Pressure regulator valve stuck in open
position. -0 Failed oil pump.
2. No starting in any drive range
for a time. Driving possible only
after repeatedly moving selector
lever to and fro.Manual valve position does not coincide
with valve body channels:
a) Selector lever shaft retaining
pin dropped out.
b) Connecting rod to manual valve
shifting.
c) Selector lever shaft nut loose.
3. No starting after shifting
lever from “P” to “D”, “S”, or “L”
(inadequate engine acceleration).a) Parking
paw1 does not disengage.
4. Sudden starting only after
increase of engine RPM.a) Band servo piston jamming.
b) Low oil level.
c) Oil pump defective.
d) Oil screen missing.
e) Sealing ball in valve body dropped out
5. Heavy jerking when starting.a) Low oil pressure.
b) Wrong modulator valve.
c) Pressure regulator valve stuck.
d) Sealing ball in valve body dropped out.
6. No starting in “D” or “S”
range, but in “L” and “R” range.a) Input sprag installed backwards.
b) Input sprag failure.
7. No starting in “D” or “S” and
“L” (proper driving in “R”; see
also point 9).a) Band worn, does not grip.
b) Band servo piston jamming.
c) Excessive leak in band servo.
d) Parking
paw1 does not disengage.