Cylinder Compression and Leak Down Test Quiz

What is the next step after performing a compression test on a cylinder and the results are out of specs?

• Perform a leak down test

• Replace the spark plugs

• Check the coolant level

• Adjust the timing marks

What does a leak down test measure?

• The percentage of air escaping from the combustion chamber

• The engine's operating temperature

• The amount of compression in the cylinder

• The level of coolant in the system

When should the engine be at operating temperature for a leak down test?

• Before removing the spark plugs

• After completing the compression test

• During the cylinder leak test

• Before connecting the air supply

What tools are required to perform a leak down test?

• Engine leak down test kit and a mechanic's stethoscope

• Dial indicator and timing marks

• Spark plug wrench and coolant tester

• Crankshaft turning tools and air compressor

What does a leakage percentage of 0-15% indicate?

• Excellent engine condition

• Good engine condition

• Fair engine condition with reduced performance

• Poor engine condition

What should be done if the piston was not set on top dead center of the compression stroke during the test?

• Rotate the crankshaft one full turn and perform the test again

• Replace the cylinder head gasket

• Check the coolant system for air bubbles

• Add engine oil through the spark plug hole

What does air bubbles coming out of the coolant tank indicate?

• Air escaping through the cylinder head gasket

• Leaking intake valves

• Leaking exhaust valves

• Excessively worn cylinder

What can cause blue exhaust smoke out of the tailpipe?

• Damaged or worn piston rings

• Leaking intake valves

• Leaking exhaust valves

• Excessively worn cylinder

What should be done if there is an excessive leak to the crankcase?

• Add engine oil through the spark plug hole and perform the leak down test again

• Replace the cylinder head

• Check the coolant system for air bubbles

• Rotate the crankshaft one full turn and perform the test again

What can white exhaust smoke out of the tailpipe indicate?

• Leak to the cooling system

• Leaking intake valves

• Leaking exhaust valves

• Excessively worn cylinder