Engine Leak-Down Test Quiz

What does a leak-down test measure in an engine?

• Oil pressure

• Cylinder leakage percentage

• RPM

• Fuel pressure

What must be done before performing a leak-down test?

• Drain the oil

• Remove the spark plugs

• Turn on the AC

• Add octane booster

Which position should the piston be in during a leak-down test?

• Bottom Dead Center (BDC)

• Any position

• Top Dead Center (TDC) on compression stroke

• TDC on exhaust stroke

A high leakage reading typically indicates:

• Strong compression

• Normal operation

• An internal problem

• A good valve seat

What is the primary tool used for a leak-down test?

• Vacuum gauge

• Compression tester

• Leak-down tester with regulator and gauges

• Torque wrench

What is a normal cylinder leakage percentage?

• 0–5%

• 10–15%

• 50–60%

• 70–80%

Leakage through the oil filler cap usually indicates a problem with:

• Head gasket

• Exhaust valve

• Piston rings

• Intake valve

Air leaking out the exhaust during a test points to:

• Intake valve issue

• Worn piston rings

• Exhaust valve leak

• Blown head gasket

Air coming from the radiator during a leak-down test indicates:

• Normal condition

• Faulty spark plug

• Intake valve leak

• Blown head gasket or cracked cylinder

What is the ideal engine condition for this test?

• Cold engine

• Engine running

• Warm engine

• Engine with no oil