A1 Engine
Repair
A four-cylinder engine has a power complaint. Cranking compression readings are shown. Specification: no cylinder may read below 75 percent of the highest reading. Which of these could be the cause?
| Cylinder | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Reading | 172 psi | 168 psi | 118 psi | 170 psi |
Technician A says correct fuel pressure at idle confirms adequate pump volume at wide-open throttle. Technician B says a restricted filter can hold normal idle pressure and drop under load. Who is right?
An engine runs at normal temperature on the highway but overheats in stop-and-go traffic. Which of these could be the cause?
Any of these could cause excessive crankcase pressure EXCEPT:
Valve lash is being checked on an engine with mechanical lifters. Before the feeler gauge is inserted between the valve stem and rocker arm, the camshaft lobe must be:
Technician A says a noise at one-half crankshaft speed points to the valve train. Technician B says a knock that quiets when one cylinder is disabled points to that cylinder. Who is right?
Piston ring end gap is being measured on a rebuilt engine. Before the feeler gauge is used, the compression ring should be placed:
What is the primary function of a turbocharger wastegate?
The engine oil level has risen above the full mark and smells of gasoline. A power balance test identifies one weak cylinder. Which of these could be the cause?
What is the primary function of the coolant bypass passage in an engine cooling system?
A cylinder leakage test on one cylinder reads 38 percent, and air is heard at the throttle body. Readings above 20 percent are unacceptable. The cause could be:
An engine idles rough with lean fuel trims. Idle quality returns to normal when the brake booster vacuum hose is pinched off. Which of these could be the cause?
After a valve seat is ground, seat runout measures 0.004 inch. Maximum allowable runout is 0.002 inch. This condition will cause:
Technician A says all spark plugs should be removed before a cranking compression test. Technician B says a cylinder that reads low on the first stroke and builds slowly indicates a burned valve. Who is right?
Which of these is the LEAST likely cause of a heater that blows cool air at idle?
An engine will not rotate with a breaker bar on the crankshaft. With the spark plugs removed, it turns freely by hand. What is the MOST likely cause?
An engine accelerates normally to 2000 rpm but loses power above that, and the exhaust manifold glows red. What is the MOST likely cause?
What is the primary function of a valve rotator?
A technician suspects combustion gases are entering the cooling system. Using a block (combustion leak) tester, the technician should:
Technician A says a vacuum gauge needle that drifts between 14 and 18 in.Hg at idle can indicate worn valve guides. Technician B says a steady 21 in.Hg reading indicates a leaking intake gasket. Who is right?
A rebuilt engine consumes oil and shows blue smoke after 3,000 miles. The cylinders were honed with worn stones and left with a glazed finish. What is the MOST likely cause?
Technician A says an internally leaking engine oil cooler can allow coolant into the engine oil. Technician B says the same failure can force oil into the cooling system. Who is right?
Which of these is the LEAST likely cause of black sooty deposits on all spark plugs?
Which of these is the LEAST likely cause of an engine that cranks normally but will not start, with fuel and spark verified?
Fresh oil is found on the timing cover, and the crankshaft pulley has a wet ring of oil on its rear face. Which of these could be the cause?
Reading Your Results: A1 Engine Repair, Test 1
A score by itself only tells you whether you passed. What follows is how to read the questions you missed on this test, because the same wrong answer can mean two very different things, and the fix is different for each one.
If you missed the questions built on a measurement
Four questions on this test hand you a reading and ask what it supports. If those are where you lost points, the gap is usually not the specification. It is what the test itself is capable of proving.
If you missed the questions where the symptom only appears sometimes
Several scenarios on this test are decided entirely by the conditions in the stem, and the conditions usually eliminate two answers before you have read them. An engine that runs cool on the highway and overheats in traffic has lost cooling capacity that only matters when airflow depends on the fan rather than road speed. An engine that pulls to 2,000 rpm and then falls flat, with the manifold glowing, is describing a restriction that only shows itself once flow demand rises. A knock at half crankshaft speed is timed to the camshaft rather than the crank, which puts it in the valve train. If you read the answers before the conditions on these, that is the habit worth changing.
If you missed the EXCEPT and LEAST likely questions
This test contains four of them, and missing several is a reading problem rather than a knowledge problem. The fix is mechanical. Before looking at the options, work out what the three real causes would have in common, then find the one that fails that trait. On the crankcase pressure question, three answers all put combustion gas past the rings or block the ventilation path, and one does neither. Finding the shared trait first turns a four-way guess into a one-way check, and it is the single highest-value habit for the real exam.
If you missed the component function questions
Three questions here ask what a part is for. On the ASE exam these are rarely definitions. They are asking what stops working when that function is lost, which is why the wastegate, the coolant bypass passage, and the valve rotator all appear as diagnostic questions rather than vocabulary. If you can state what a component does but not what its failure looks like from the driver's seat, that is the half worth studying.