ASE T3 DIESEL ENGINE TEST |ACTUAL
QUESTIONS AND VERIFIED ANSWERS|BRAND NEW
2026-2027 UPDATE|GRADED A+
Question 1
1. The driver of a truck says he hears a grinding noise
when the transmission is in neutral and the truck is
stopped; but the noise goes away when the clutch
pedal is depressed. Which of these could be the
cause?
A. worn pilot bearing
B. worn input shaft bearing
C. worn clutch release (throwout) bearing
D. worn auxiliary transmission countershaft bearing
CORRECT ANSWER
1. The correct answer is B. The noise occurs only when the input shaft is rotating. The
bearing handles the relative motion between shaft and case and thus works only when the
shaft is moving. This occurs when the truck isidling with the clutch engaged. The noise goes
away when the clutch pedal is depressed because the input shaft then stops turning and the
bearing is stationary. The other symptoms would only occur when either the clutch is
engaged or when the transmission is being shifted.
Question 2
2. A manual shift transmission slips out of fifth gear. The MOST likely cause of this problem
is:
A. a broken detent spring
B. too much shaft and gear spline wear
C. worn countershaft bearings
1
,D. a chipped countershaft drive gear
CORRECT ANSWER
2. The correct answer is A. The detent ball lightly holds the gear lever in place when a shift is
complete. With a broken spring, there will be no pressure holding the ball in the detent
located in the shift rail. Vibration can easily cause the direct drive (top gear) shift collar to
slide and disengage. Answers B and D would cause grinding when shifting into gear, while
answer C would cause a whining noise.
Question 3
3. The shift lever on a single countershaft transmission is hard to move. Which of these is
the MOST likely cause?
A. bent shift rails
B. galled sliding clutch gears
C. worn detent springs
D. too much mainshaft gear end-play
CORRECT ANSWER
3. The correct answer is B. Galled surfaces on the sliding clutches would make it difficult for
them to slide along the shafts and in and out of the gears. Bent shift rails and worn detent
springs would cause the transmission to slip out of gear. Too much mainshaft gear end play
would cause shifting to be next to impossible and the transmission will exhibit a growling
noise.
Question 4
4. In a transmission that has been taken apart, all of the bearings are excessively worn.
Technician A says the cause could be moisture in the lubricant. Technician B says the cause
could be too high an operating
temperature. Who is right?
A. Technician A only
B. Technician B only
2
,C. Both A and B
D. Neither A or B
CORRECT ANSWER
4. The correct answer is C, both technicians are right. Bearing wear often occurs when the
viscosity of the gear lube is too low. Water dilutes the gear lube, thereby thinning it. Heat
also thins the gear lube by breaking it down chemically.
Question 5
5. A truck with a high-torque, low-rpm engine exhibits a great deal of gear noise, as well as
wear of the splines on various drivetrain parts. The truck uses a rigid disc clutch. All the U-
joint angles are acceptable. The MOST likely cause of this problem is that the
A Driver abuses the clutch by releasing it too rapidly
B. Engine produces torsional vibration, which should be removed from the drivetrain by
using a dampened disc clutch.
C. Engine mounts are worn.
D. Engine rating is such that the transmission requires the use of an oil cooler.
CORRECT ANSWER
5. The correct answer is B. A rigid clutch cannot dampen the severe vibrations produced by
modern high torque diesels. The only other source of the kind of vibration torque that would
cause such damage would be misaligned driveshafts, and they have been found to be OK.
Question 6
6. A truck fleet presently uses transmissions with an overdrive top gear ratio. It wishes to
convert its trucks to the use of direct-drive transmissions. In order to get approximately
the same number of engine revolutions per mile in top gear, the company would have to:
A convert the gearing in its rear axles to a higher (numerical) ratio
B. convert the gearing in its rear axles to a lower (numerical) ratio
C. it need not convert (the same rear axle ratio will produce the same engine revolutions per
mile)
3
, D. convert to lower-profile tires (which would turn more revolutions per mile)
CORRECT ANSWER
6. The correct answer is B. On vehicles with overdrive. the engine turns more slowly than the
transmission out put shaft and the driveshafts at any given speed. With a direct drive
transmission, the engine must turn at the same speed as the driveshafts-in other words,
with the same axle, faster. A numerically lower axle, requiring fewer revolutions of the
driveshafts, would be the only means of bringing the required rpm of engine and drive
shafts back down.
Question 7
7. Which one of the following operating conditions does NOT indicate to the technician
that the truck would operate more reliably with a transmission oil cooler?
A. truck is rated at 350 hp
B. truck has a power rating of 450 hp
C. truck cab has the maximum number of aerodynamic devices to smooth air flow
D. truck normally cruises in an overdrive ratio of 0.85:1
CORRECT ANSWER
7. The correct answer is A. Any truck rated less than 400 hp is normally approved for
operation without a transmission oil cooler; only trucks of 400 hp and up require them.
Question 8
8. A hydraulic clutch slave cylinder is being replaced. What should the technician do first?
A. disconnect the clutch pedal pushrod
B. remove the slave cylinder from its mounting
C. disconnect the hydraulic line
D. adjust clutch pedal free-play
CORRECT ANSWER
4
QUESTIONS AND VERIFIED ANSWERS|BRAND NEW
2026-2027 UPDATE|GRADED A+
Question 1
1. The driver of a truck says he hears a grinding noise
when the transmission is in neutral and the truck is
stopped; but the noise goes away when the clutch
pedal is depressed. Which of these could be the
cause?
A. worn pilot bearing
B. worn input shaft bearing
C. worn clutch release (throwout) bearing
D. worn auxiliary transmission countershaft bearing
CORRECT ANSWER
1. The correct answer is B. The noise occurs only when the input shaft is rotating. The
bearing handles the relative motion between shaft and case and thus works only when the
shaft is moving. This occurs when the truck isidling with the clutch engaged. The noise goes
away when the clutch pedal is depressed because the input shaft then stops turning and the
bearing is stationary. The other symptoms would only occur when either the clutch is
engaged or when the transmission is being shifted.
Question 2
2. A manual shift transmission slips out of fifth gear. The MOST likely cause of this problem
is:
A. a broken detent spring
B. too much shaft and gear spline wear
C. worn countershaft bearings
1
,D. a chipped countershaft drive gear
CORRECT ANSWER
2. The correct answer is A. The detent ball lightly holds the gear lever in place when a shift is
complete. With a broken spring, there will be no pressure holding the ball in the detent
located in the shift rail. Vibration can easily cause the direct drive (top gear) shift collar to
slide and disengage. Answers B and D would cause grinding when shifting into gear, while
answer C would cause a whining noise.
Question 3
3. The shift lever on a single countershaft transmission is hard to move. Which of these is
the MOST likely cause?
A. bent shift rails
B. galled sliding clutch gears
C. worn detent springs
D. too much mainshaft gear end-play
CORRECT ANSWER
3. The correct answer is B. Galled surfaces on the sliding clutches would make it difficult for
them to slide along the shafts and in and out of the gears. Bent shift rails and worn detent
springs would cause the transmission to slip out of gear. Too much mainshaft gear end play
would cause shifting to be next to impossible and the transmission will exhibit a growling
noise.
Question 4
4. In a transmission that has been taken apart, all of the bearings are excessively worn.
Technician A says the cause could be moisture in the lubricant. Technician B says the cause
could be too high an operating
temperature. Who is right?
A. Technician A only
B. Technician B only
2
,C. Both A and B
D. Neither A or B
CORRECT ANSWER
4. The correct answer is C, both technicians are right. Bearing wear often occurs when the
viscosity of the gear lube is too low. Water dilutes the gear lube, thereby thinning it. Heat
also thins the gear lube by breaking it down chemically.
Question 5
5. A truck with a high-torque, low-rpm engine exhibits a great deal of gear noise, as well as
wear of the splines on various drivetrain parts. The truck uses a rigid disc clutch. All the U-
joint angles are acceptable. The MOST likely cause of this problem is that the
A Driver abuses the clutch by releasing it too rapidly
B. Engine produces torsional vibration, which should be removed from the drivetrain by
using a dampened disc clutch.
C. Engine mounts are worn.
D. Engine rating is such that the transmission requires the use of an oil cooler.
CORRECT ANSWER
5. The correct answer is B. A rigid clutch cannot dampen the severe vibrations produced by
modern high torque diesels. The only other source of the kind of vibration torque that would
cause such damage would be misaligned driveshafts, and they have been found to be OK.
Question 6
6. A truck fleet presently uses transmissions with an overdrive top gear ratio. It wishes to
convert its trucks to the use of direct-drive transmissions. In order to get approximately
the same number of engine revolutions per mile in top gear, the company would have to:
A convert the gearing in its rear axles to a higher (numerical) ratio
B. convert the gearing in its rear axles to a lower (numerical) ratio
C. it need not convert (the same rear axle ratio will produce the same engine revolutions per
mile)
3
, D. convert to lower-profile tires (which would turn more revolutions per mile)
CORRECT ANSWER
6. The correct answer is B. On vehicles with overdrive. the engine turns more slowly than the
transmission out put shaft and the driveshafts at any given speed. With a direct drive
transmission, the engine must turn at the same speed as the driveshafts-in other words,
with the same axle, faster. A numerically lower axle, requiring fewer revolutions of the
driveshafts, would be the only means of bringing the required rpm of engine and drive
shafts back down.
Question 7
7. Which one of the following operating conditions does NOT indicate to the technician
that the truck would operate more reliably with a transmission oil cooler?
A. truck is rated at 350 hp
B. truck has a power rating of 450 hp
C. truck cab has the maximum number of aerodynamic devices to smooth air flow
D. truck normally cruises in an overdrive ratio of 0.85:1
CORRECT ANSWER
7. The correct answer is A. Any truck rated less than 400 hp is normally approved for
operation without a transmission oil cooler; only trucks of 400 hp and up require them.
Question 8
8. A hydraulic clutch slave cylinder is being replaced. What should the technician do first?
A. disconnect the clutch pedal pushrod
B. remove the slave cylinder from its mounting
C. disconnect the hydraulic line
D. adjust clutch pedal free-play
CORRECT ANSWER
4
