Lesson 2/Learning Event 3
Release the air cleaner body-to-base mounting clamps, and remove the body from the base. Check the
condition of the rubber seal and the mounting clamps to make sure that the base seals air-tight against the
cleaner body. Check the filter element for excess dirt, evidence of water, hardening of the filter material,
and for any external damage.
Make sure that you look over the entire fuel and air intake systems for anything that seems to be wrong.
Look for broken parts, loose or worn parts, and leaks. Also look for anything that indicates a part which
may be in trouble or may be causing trouble. This is another method of learning symptoms that may help
you locate trouble.
If the engine will run, start it and look for leaks around the fuel lines and connections. This is known as an
"operational" or functional inspection.
Remember, you have five senses that can help you locate trouble. For example, you can SMELL fuel or you
might SEE it leaking. You might HEAR the air whistling as it leaks into a hole in the air cleaner hose or
past a loose hose.
INSPECTING A MALFUNCTIONING VEHICLE
Once you have learned all that you can, look over the "symptoms" reported on this vehicle. See if they point
to any part that may be defective or may be causing the trouble. Let's say that the truck has lost power.
Another symptom, learned from the driver, is that it was using more fuel than normal. These two
symptoms point out that the engine is either getting too much fuel or not enough air. One of the more
probable causes in this case is a partially plugged air cleaner.
However, don't start removing parts!
Don't be hasty and replace parts until all symptoms have been
Symptoms that show up in engine power, fuel consumption, and the exhaust system can all be caused by a
faulty air intake component. A poor troubleshooter may try to stop the engine from using too much fuel by
repairing or replacing parts in the fuel system.
The main thing is to try to find out what is actually causing the trouble. This is called "diagnosing the
symptoms" and "isolating the fault."