ASE A1 Engine Repair Practice Test
1. An engine has been compression tested. The number two cylinder is below specifications. After injecting oil, the pressure does not increase. The engine has:
- A. A faulty head gasket.
- B. A bad valve.
- C. Worn piston rings.
- D. A hole in the piston.
Answer A is wrong. A faulty head gasket will affect two adjacent cylinders.
Answer B is correct. This second compression test designed to increase compression by increasing the seal between the rings and the cylinder wall is called a wet compression test. If there is little or no change in compression after adding oil, the engine has a bad valve, typically an exhaust valve.
Answer C is wrong. If cylinder compression increases after adding a teaspoon of engine oil, the piston rings have worn.
Answer D is wrong. If there's a hole in the piston, there would be no compression in the cylinder.
2. One valve tip on a cylinder head is much higher than the others. The MOST likely cause of this is:
- A. Weak spring tension.
- B. Valve spring installed height.
- C. The valve seat.
- D. Loose head bolts.
Answer A is wrong. Weak spring tension is not a likely cause. It results in valve float and a misfire at high engine speeds. Excessive spring pressure can cause the valve's neck to stretch.
Answer B is wrong. The valve spring installed height is the distance from the pocket or cup where the spring sits to the underside of the retainer/rotator with the valve closed.
Answer C is correct. A worn valve face or seat is the most likely cause. Measure the valve stem installed height if one tip is higher than the others.
Answer D is wrong. Loose head bolts result in a loss of compression, overheating and white colored exhaust.
3. During the initial inspection of an engine, the technician notices that the oil filter has swollen larger than normal. All of the following will result in this condition EXCEPT:
- A. Contaminated oil.
- B. Stuck closed oil pressure relief valve.
- C. Stuck closed oil filter bypass valve.
- D. Worn main crankshaft bearings.
Answer A is wrong. Contaminated oil will clog the filter, if the oil filter bypass valve is stuck closed. This will result in a swollen and ballooned filter.
Answer B is wrong. A stuck closed oil pressure relief valve would cause high oil pressure and a ballooned oil filter.
Answer C is wrong. A clogged filter and a stuck closed oil bypass valve would result in a ballooned filter.
Answer D is correct. Each of these conditions would result in a ballooned oil filter except main bearings. Worn engine bearings and faulty oil pumps result in low oil pressure.
4. The measuring tool illustrated above is a:
- A. Dial indicator for measuring crankshaft rod journals.
- B. Micrometer for measuring crankshaft rod journals.
- C. Dial indicator for measuring crankshaft endplay.
- D. Bore gauge for measuring cylinder wall thickness.
Answer A is wrong. Answer C is correct.
Answer B is wrong. Answer C is correct.
Answer C is correct. A dial gauge is used to measure end-play clearance.
Answer D is wrong. Answer C is correct. Place the indicator tip on the crankshaft flange. Use a pry bar or a large screwdriver to move the crankshaft back and forth.
5. A V-8 engine with a liquid cooled supercharger is detonating during acceleration. Technician A says to inspect the intercooler's radiator for debris. Technician B says a special adapter may be required to pressure test the system. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. The system contains the intercooler, the radiator, piping, coolant reservoir, etc. The intercooler's radiator, usually located at the front of the vehicle where fresh air can pass through, releases heat to the atmosphere.
Answer B is wrong. The intercooler, not the radiator, on larger V8 engines is mounted between the supercharger and the intake maniflod.
Answer C is correct. Superchargers require an intercooler to cool the heated compessed air charge before entering the air inlet. This cooled air prevents harmful detonation.
Answer D is wrong. They typically require a 50/50 mixture of antifreeze to water and are leak tested similar to the engine's cooling system.