A1 Engine
Repair
An engine has an oil pressure complaint. Readings are taken with a mechanical gauge on a warm engine. Which of these could be the cause?
| Engine speed | Specification | Measured |
|---|---|---|
| Idle (700 rpm) | 15--25 psi | 9 psi |
| 2000 rpm | 45--60 psi | 28 psi |
Technician A says a relative compression test compares cylinders using starter current draw. Technician B says the spark plugs must be removed before a relative compression test. Who is right?
An engine runs normally below 4000 rpm but misses, pops, and backfires above that speed. Which of these could be the cause?
Any of these could cause hard starting when the engine is hot EXCEPT:
What is the primary function of bearing crush in a connecting rod bearing?
During a cylinder power balance test, disabling cylinders 1, 2, and 4 each drops engine speed about 80 rpm. Disabling cylinder 3 drops speed 10 rpm. This indicates:
Technician A says a coolant hydrometer reads the correct freeze point on hot coolant without correction. Technician B says a refractometer determines freeze protection from the coolant's refractive index. Who is right?
An oil leak cannot be located visually. To trace it with fluorescent dye, the technician should first:
A turbocharged engine has blue smoke at idle and oil pooled in the intake duct ahead of the throttle. What is the MOST likely cause?
After a timing belt replacement, an engine starts but has low power, and cranking compression is low on every cylinder. Which of these could be the cause?
Which of these is the LEAST likely cause of coolant that is dark brown and contains rust particles?
A cylinder measures 3.786 in. at the top of ring travel and 3.780 in. at the bottom. Maximum allowable taper is 0.005 in. The technician should:
Technician A says atmospheric pressure falls at higher altitude, reducing the air an engine can draw in. Technician B says volumetric efficiency compares actual intake air to the cylinder's theoretical capacity. Who is right?
What is the primary function of the crankshaft vibration damper?
Timing chain wear is being checked without removing the timing cover. The technician turns the crankshaft and watches for:
An engine will not crank. The starter draws very high current, and the crankshaft will not turn by hand with all spark plugs removed. What is the MOST likely cause?
A coolant drip appears from a small hole below the water pump pulley, along with a rumbling noise from that area. Which of these could be the cause?
Which of these is the LEAST likely cause of blue smoke from the tailpipe during hard acceleration?
Technician A says a cracked spark plug boot can let secondary voltage arc to ground under load. Technician B says a spark plug gap wider than specification lowers the voltage the coil must produce. Who is right?
What is the primary function of the oil pump pressure relief valve?
A vehicle stored outdoors for two years now has a loud tapping noise and a misfire on one cylinder. What is the MOST likely cause?
An engine overheats, and bubbles rise steadily in the radiator with the engine running and the cap removed. Which of these could be the cause?
Which of these is the LEAST likely cause of a fuel odor that is strongest right after the engine is shut off?
Technician A says excessive crankshaft end play can cause a knock that is loudest at idle. Technician B says a loose flexplate can cause a knock that appears under load. Who is right?
A fuel pressure gauge is connected to the rail. To check for a leaking injector or pump check valve, the technician should:
Reading Your Results: A1 Engine Repair, Test 2
This test comes at the same content areas from the bench rather than the driveway. There are more measurements with a published limit attached and more questions about the order a procedure has to run in, so the questions you missed here point somewhere different than the ones on Test 1 would.
If you missed the questions with a measurement and a limit
Three questions on this test give you numbers and a specification. When those go wrong, the problem is usually the setup rather than the arithmetic, because each of these readings is only valid under a condition the question expects you to know.
If you missed the procedure questions
Four questions here turn on sequence. Timing chain slack is judged by how far the crankshaft rotates before the camshaft follows, which means the measurement is the rotation rather than the chain itself. Tracing a leak with fluorescent dye only works if the area is cleaned first, because old residue will fluoresce and send you to the wrong seal. Checking for a leaking injector or check valve means pressurizing the rail and then watching whether it holds, so the pressure has to be there before the observation starts. On the exam, these questions are asking whether you know what would invalidate the result.
If you missed the component function questions
The three component questions on this test all have a failure story attached. Bearing crush is what holds the insert tight in its bore so it transfers heat and cannot spin, which is why bearings are never filed or shimmed to fit. The crankshaft vibration damper absorbs torsional vibration along the crank, so a damper with a separated rubber ring puts that vibration back into the crankshaft and eventually into the timing components. The oil pump pressure relief valve sets a ceiling rather than a supply, which is why raising its spring pressure hides a clearance problem instead of correcting one.
If you missed the EXCEPT and LEAST likely questions
There are four on this test, and the method is the same one that works on the real exam. Identify what the three real causes share before you look for the odd one out. On the blue smoke question, three answers all give oil a path into the combustion chamber under load and one does not. On the hot hard-start question, three affect fuel delivery or spark when everything under the hood is heat-soaked, and one is unrelated to temperature. Naming the shared trait first is faster and far more reliable than reasoning through four options one at a time.