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ASE A1 Engine Repair Practice Test1. A vehicle has heavy white smoke emitting from its tailpipe at all engine speeds. The cause of this problem is:
- A. Worn piston rings. B. A leaking head gasket.
- C. Worn valve seals.
- D. A leaking fuel injector.
Answer A is wrong. Worn piston rings result in blow-by and oil burning in the combustion chamber producing blue/gray smoke.
Answer B is correct. A leaking head gasket results in a coolant leak from the jacket to the cylinder producing white/gray smoke.
Answer C is wrong. Leaking valve seals result in oil entering the combustion chamber, especially overnight or after sitting a while. At start up the engine will produce blue/gray smoke from this oil burning in the combustion chamber. This symptom may go away after the engine runs a while, but return again after the vehicle sits.
Answer D is wrong. A leaking fuel injector results in a rich condition producing excessive hydrocarbons and black smoke.
2. A vacuum gauge is connected to the intake manifold of an engine. The needle fluctuates between (15 in. Hg and 20 in. Hg) at idle. This vacuum gauge reading indicates:
- A. A normal condition.
- B. Late ignition or valve timing. C. A sticking valve or misfire.
- D. A restricted exhaust system.
Answer A is wrong. If the gauge reads steady (17-22 in Hg) this indicates a normal running engine.
Answer B is wrong. If the gauge reads low (15-20 in Hg) this indicates late valve or ignition timing, leaking manifold gasket, low compression, leaking carburetor, or stuck throttle valve.
Answer C is correct. If the gauge readings fluctuate between (15 and 20 in Hg) this indicates a stuck valve or engine miss.
Answer D is wrong. If the gauge reading drops slowly at an idle this indicates a clogged or blocked exhaust.
3. Technician A says an engines main bearing insert has a hole that must align with the matching bores oil supply hole. Technician B says that crankshaft bore alignment can be checked with a feeler gauge and a straightedge. Who is correct?
- A. Technician A
- B. Technician B C. Both A and B
- D. Neither A or B
Answer A is wrong. Both Technicians are correct.
Answer B is wrong. Both Technicians are correct.
Answer C is correct. Always make sure the two holes and all bores are in alignment when replacing the crankshaft bearing inserts.
Answer D is wrong. Both Technicians are correct.
4. A cylinder power balance test is being performed on a vehicle with sequential fuel injection. Two adjacent cylinders are under performing. Technician A says this could be due to a faulty head gasket. Technician B says this could be due to leaking secondary insulation. Who is correct?
Answer A is wrong. Both technicians are correct.
Answer B is wrong. Both technicians are correct.
Answer C is correct. Both restricted fuel injectors and leaking secondary wires will reduce the cylinders contribution. It could also be a faulty or blown head gasket.
Answer D is wrong. Both technicians are correct.
5. Two technicians are discussing hydraulic lifter preload. Technician A says excessive preload will cause high manifold vacuum. Technician B says insufficient preload will cause excessive valve train noise. Who is correct?
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