Five free practice questions on lubrication and cooling systems: content area D of the ASE T2 Diesel Engines test, 6 of its 55 scored questions (10.9%). They are in the ASE format: four options, one best answer. Answer each one before opening the explanation. No account, no email.
01The questions
-
A replacement turbocharger on a truck diesel gets a new oil drain hose. How must the drain hose be routed?
- Looped up to keep the bearings flooded
- Downhill into the pan above the oil level
- Into the filter head so the oil is filtered
- Below the oil level to keep air out
Show the answer
B. Correct. Oil leaves the center housing by gravity, foamy and with no pressure behind it, so the hose must fall all the way to the engine with no loops, sags or kinks and enter above the oil in the pan. Anything that holds the oil back floods the shaft seals and shows as oil in the intake or exhaust.
Why not the others
A. A loop or sag holds oil in the hose and the center housing, and the trapped oil backs up past the shaft seals into the compressor and turbine. The bearings are fed by the pressurized feed line; the drain only carries oil away.
C. The filter head is under full pump pressure, and a gravity drain cannot flow into a pressurized passage, so oil would back up in the center housing. The drain empties into the crankcase above the oil level.
D. An outlet below the oil level has to push against the oil in the pan, which a gravity drain cannot do, so oil backs up in the center housing and past the seals. The drain enters the crankcase above the oil level.
ID T2-D-006 · Task T2-D-5 (ASE task list)
-
The specified amount of fresh oil has gone into a truck diesel after a change of its two full-flow filters; the engine also has an oil cooler, and its dipstick is marked for reading with the engine stopped. How is the oil level correctly confirmed?
- Read the dipstick right after filling, before starting
- Read the dipstick at idle once oil pressure comes up
- Run it, stop it, let it drain back, then read
- Run it, shut it off, and read the dipstick at once
Show the answer
C. Correct. Running the engine fills the new filters, the cooler and the galleries, and waiting the time the manufacturer specifies lets oil drain back to the pan before the dipstick is read. Topping up only after that avoids both a low level and the overfill that comes from reading too soon.
Why not the others
A. Before the first start the new filters and the cooler passages are still empty, so the reading does not show where the level will settle. Run the engine, shut it down, let the oil drain back for the time the manufacturer specifies, then check.
B. With the engine running, much of the oil is up in the galleries and filters, and this dipstick is marked for a stopped engine, so it reads low and invites overfilling. The level is read after shutdown and the drain-back wait.
D. Read at once, the oil has not drained back from the upper engine, so the level looks low and a technician may overfill. The manufacturer's wait after shutdown comes before the reading.
ID T2-D-008 · Task T2-D-6 (ASE task list)
-
A medium-duty truck's fan is driven by a pair of V-belts, and one belt has a cracked sidewall. The pulley grooves gauge good. What should be done?
- Replace only the cracked belt, set to new-belt tension
- Replace both belts and both pulleys as one assembly
- Replace only the cracked belt, set to used-belt tension
- Replace both belts with a new matched set
Show the answer
D. Correct. Belts in a multiple drive share the load only when their lengths match. A new belt run beside a worn, stretched one takes nearly all the load, so the set is replaced together and tensioned to spec.
Why not the others
A. A new belt beside a stretched one rides higher in its groove and carries most of the load, so it wears fast and the old belt slips. Both are replaced with a new matched set.
B. The pulley grooves gauge good, so new pulleys are not needed. The repair is a new matched set of belts.
C. Used-belt tension on a new belt leaves it loose, and it still will not share the load with the stretched one. Replace both with a matched set and tension them as new belts.
ID T2-D-009 · Task T2-D-7 (ASE task list)
-
A truck's multi-rib accessory belt is made of modern EPDM rubber and shows no cracks at its PMI. Technician A says that with no cracks the belt is not worn and can stay in service. Technician B says a rib-depth wear gauge pressed into the grooves shows whether rib wear has reached the replacement point. Who is right?
- A only
- B only
- Both A and B
- Neither A nor B
Show the answer
B. Correct. Technician B is right: an EPDM belt wears like a tire, losing rubber from its ribs until it rides low in the grooves and slips, and a wear gauge shows how far that has gone. Technician A is wrong, because the lack of cracks says little about wear on this material.
Why not the others
A. Technician A is wrong: EPDM belts seldom crack and wear instead by losing rib material, so a crack-free belt can be worn out. Technician B is right that a rib-depth gauge measures that wear.
C. Only Technician B is right. Technician A's crack check suits older neoprene belts; an EPDM belt can be worn out with no cracks, which is why the gauge is used.
D. Technician B is right: the rib-depth gauge shows material loss, the way an EPDM belt actually wears. Technician A is wrong that a crack-free belt is unworn.
ID T2-D-010 · Task T2-D-7 (ASE task list)
-
At a PM, a tractor's conventional coolant is tested with strips. The coolant maker specifies 1,200 to 3,200 ppm nitrite for this coolant; the strip reads 600 ppm, and the glycol concentration reads within its specification. What should be done?
- Drain some coolant and refill with water
- Record it as in range and retest at the next PM
- Dose SCA by the chart and retest
- Add full-strength antifreeze to the system
Show the answer
C. Correct. At 600 ppm the nitrite is well below the 1,200 ppm minimum, so the liners are losing their protection against cavitation. Adding the SCA amount the chart gives for that reading, by liquid or a charged coolant filter, and retesting brings it back into range.
Why not the others
A. Diluting is the response to too much SCA, and this reading is too little. Water would also lower the glycol concentration that is already correct; add SCA instead.
B. The reading of 600 ppm is half the 1,200 ppm minimum, not within range. Left alone, the liners have too little protection; add SCA by the chart and retest.
D. The glycol is already in specification, so more antifreeze would push it past its limit while doing little for the nitrite. The shortfall is in the additive, which is dosed directly.
ID T2-D-014 · Task T2-D-11 (ASE task list)
02Answer key
| Question | Answer |
|---|---|
| Q1 | B |
| Q2 | C |
| Q3 | D |
| Q4 | B |
| Q5 | C |
03What area D covers
This content area covers keeping a truck diesel lubricated and cooled: oil pressure and temperature sensors and gauges, oil pumps, regulator and bypass valves, oil coolers and oil thermostats, turbocharger oil feed and drain, oil and filter service, belts and tensioners, coolant sensors, thermostats and seals, filling and bleeding, coolant filters and additives, water pumps, caps and surge tanks, and fans and shrouds.
The ASE test specification calls this content area “Lubrication and Cooling Systems Diagnosis and Repair”. It carries 6 of the 55 scored questions, 10.9% of the test.
- Verify oil pressure, oil temperature and their sensors
- Inspect oil pumps, regulator valves and bypass valves
- Service oil coolers, oil thermostats and turbocharger oil lines
- Change oil and filters with the specified oil
- Inspect belts, pulleys and tensioners
- Test coolant sensors, thermostats and their seals
- Fill, bleed and condition the coolant
- Check water pumps, caps, fans and shrouds
04What the questions turn on
Gauge first, then the circuit
A mechanical gauge shows whether low oil pressure is real. With the gauge reading normal and 0 volts arriving on the sensor's 5-volt reference, the reference wire is open. A thermistor showing its hot resistance in a warm bath has failed.
Thermostats and their seals
Hot oil with normal coolant temperature points to an oil thermostat stuck in bypass, which keeps oil out of a good cooler. Overcooling after new coolant thermostats can come from sleeve seals left out, letting coolant reach the radiator all the time.
Keep the additive in range
On conventional coolant, nitrite below the coolant maker's minimum leaves the liners open to cavitation, so SCA is dosed by the chart and the coolant retested. A charged coolant filter adds nothing if both of its shutoff valves stay closed.
Oil category and grade
The API category and the SAE viscosity grade are separate requirements. FA-4 oils are not backward compatible with CK-4, so an engine whose maker lists only 15W-40 CK-4 takes neither an FA-4 oil nor a 10W-30.
05The other content areas
The T2 test has eight content areas. Each has its own page of free questions:
The ASE T2 Diesel Engines practice test page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.
ToolboxPrep is an independent study site, not affiliated with or endorsed by ASE (the National Institute for Automotive Service Excellence). Our questions are original, written from ASE’s published test specifications and task lists and other public sources. They are not actual ASE test questions and not recalled or “brain dump” questions. ASE is a trademark of its owner, and we never use the ASE logo. Standards and service information are cited, not reproduced.