Engine noise diagnosis

Proper engine noise diagnosis is a very important issue to address. In fact improper diagnosis can lead you on a wild goose chase.

For example, if you believe the engine noise is a wrist pin that is loose and you remove the engine and disassemble it and then find out that it was a camshaft thrust plate that came loose.

You will have performed a couple of day’s work that was not needed. Often a malfunction in the engine will reveal itself first as an unusual noise.

This can happen before the problem affects the driveability of the vehicle. Some of these problems include badly worn piston rings or ring lands, loose wrist pins, worn main bearings or connecting rod bearings, and loose valve train components all produced telltale noises that are unique.

With a little practice, a do it yourself auto mechanic can gain the experience to interpret engine noises and distinguish them from one another.

This can and will avoid a costly and time-consuming engine tare down that could be avoided. Always take the extra time to make a proper noise analysis before doing any engine repair work.

Also having a heads up on the noise can reduce repair costs by addressing the problem before irreversible engine damage occurs.

Diagnosis with a stethoscope

This is okay for loud noises, but not for small or developing noises. Especially since the procedure for using a stethoscope is simple and the tool is inexpensive.

I own the Lisle on the right but I paid $30 on the Brand name tool truck. Use the tip of the metal probe on the mechanics stethoscope to trace the sound until it reaches its maximum intensity.

Once the precise location has been found, the sound can be better evaluated and diagnosed. A mechanic's stethoscope will provide much clearer and accurate results.

The newest tools to hit the market are electronic listening devices. This may be overkill for the do it yourself car mechanic. But with this tool you can tune into the noise and cancel out surrounding noises. This can lead to even more accurate engine noise diagnosis.

Common engine noise diagnosis

When a piston slaps against a cylinder wall, the sound is like a hollow dull bell type sound. Piston slap is often caused by worn pistons or cylinder walls. In extreme situations on engines with high mileage, you can have collapsed piston skirts and alignment issues with connecting rods.

If all the wrist pins are loose, this will sound like an overwhelming rattling inside the engine.

This sound is described and as a double knock, because it will cause a noise at the top of the piston travel and when the piston changes direction it will make another noise.

This noise is most notable when the engine is idling and the engine is also hot.

An engine rod bearing noise is near the top of the most common internal engine noises that you'll hear. This would be considered a lower end knock.

A knocking rod bearing is the result of a worn or loose connecting rod bearing. This noise is heard at idle as well as higher rpms.

This depends on how badly the bearings are worn. The noise can range from a light tap to a heavy knock or even a pounding, when the bearing becomes extremely damaged or spun. When the noise is at this extreme level removing the oil pan may expose the problem.

The lifter noise is one of the most common complaints I received from customers. Also note that some lifter noise is considered normal from several manufacturers such as General Motors.

The engine lifter noise is characterized by a light regular clicking sound that is more noticeable when the engine is idling. It can be a result of the excessive clearance in the valve train.

A clearance problem can be located by inserting a feeler gauge between each lifter and valve tip. This will differ depending on cam design.

Engine lifter noise can be caused by improper valve adjustment, worn or damaged parts, hydraulic lifters that are clogged with sludge or dirt, or lack of engine oil pressure.

Give this engine noise diagnosis resource page a

This page address is the most common engine noise diagnosis that you will run into. There can be other causes and a few different types of sounds that your engine may exhibit. For more information about automobile power plant problems this next link will take you from engine noise diagnosis to automotive engines page


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