What you should know about engine noise?
While engine noises can indicate problems. they are difficult to interpret correctly; inexperienced mechanics can be seriously misled by them.
Professional mechanics often use a special stethoscope (which looks like a doctor's stethoscope) for isolating engine noises.
You can do nearly as well with a "sounding stick" which can be an ordinary piece of dowling, a length of broom handle or a section of small hose.
By placing one end in contact with the area 10 which you want to listen and the other end near your ear, you can hear sounds emanating from that area. The first time you do this. you
may be horrified at the strange sounds coming from even a normal engine. If possible, have an experienced friend or mechanic help you sort out the noises.
Consider the following when troubleshooting engine noises:
1. Knocking or pinging during acceleration caused by using a lower octane fuel than recommended. May also be caused by poor fuel. Pinging can also be caused by a spark plug of the wrong heat range.
2. Slapping or rattling noises at low speed or during acceleration-may be caused by piston slap. i.e., excessive piston-cylinder wall clearance.
3. Knocking or rapping while decelerating-usually caused by excessive rod bearing clearance.
4. Persistent knocking and vibration-usually caused by worn main bearing(s).
5. Rapid on-off squeai --compression leak around cylinder head gasket or spark plug(s).
6. Valve traillnoise -check for the following:
a. Valves adjusted incorrectly.
b. Loose valve adjuster.
c. Valve Slicking in guide.
d. Low oil pressure.
e. Damaged rocker arm or shaft. Rocker ann may be binding on shaft.