Engine Diagnostics!

Engine Diagnostics!

I will be providing scenarios and you will select the next step in the diagnostic process.

Good Luck!

Problem:

Problem: Mr. Washington brought his 2005 Lexus into the shop complaining of a knocking sound that seemed to coming from the engine.

Open Ended

Before doing any diagnostics what part or area on the engine do you think could be causing this problem. No right or wrong answers.

More information:

After asking some more specific questions to the owner you find that the problem occurs at all engine temperatures. The knock noise is the same when the engine is hot or cold, but it does seem to occur more at idle compared to other engine speeds.

Open Ended

Based on this new information do you think it is any other parts or areas that could be causing the concern?

Open Ended

What would you do now to begin to diagnositic

Poll

What would you do now to begin testing/diagnosing this concern?

• Pull spark plugs

• Pinpoint the noise to a component or specific area

• Drain the oil and look for metals

• Return the car to the customer and say it is normal.

My choice would be to use a stethoscope in an attempt to pinpoint the noise.

• This will let you listen to areas of the engine and find out where the noise is the loudest.

Diagnostic find #1

• The knocking noise is the loudest when touching the stethoscope to the sides of the engine timing cover.

Multiple Choice

What would be your next step in this situation?

• Remove and replace the engine

• Remove the timing cover and inspect the timing chain

• Remove the spark plugs

• Connect an OBD 2 Scantool

After removing the timing cover you notice...

• Timing chain is worn

• Timing guides are worn

• Contact marks on the timing cover

Multiple Choice

What repair would resolve this customers concern and get them back on the road?

• A fresh oil change

• A new timing chain and guides

• A new timing cover gasket

• New piston rings

Scenario #1

Mr. Washington's Lexus had a bad timing chain and guides that caused the chain slap noise, plus may have affected the engine timing causing the engine knock.