Why Does My Volvo Engine Rattle?

Engine failure is something you do not have to worry if you own a Volvo. But like any Volvo owner will tell you, there’s a price you pay for that assurance. You have no choice but to take good care of the engine.  Slack a little and before you know it, you’ll hear rattling noise each time you drive. The longer you assume the rattling noise, the easier you make it for the engine to completely break down.  While a rattling noise may be as a result of a worn out belt that will cost only a few dollars, a total engine overall or replacement will cost thousands of dollars.

The Source

A simple inspection underneath the hood can help you identify the source of the rattling noise and fix the problem.  While most causes of rattling noises in the engine may be within the engine block, there are some you can identify even without a detailed diagnosis. Some of the causes of this defect include:

Cracked Flex Plate

 Volvo models that use automatic transmission have a metal disc referred to as the flex plate. As the name implies, it acts as a flex shock device between the engine crankshaft and the torque converter.  It is made of a steel, circular shaped disc with perforated holes. To ensure proper alignment and smooth running, the disc must be properly balanced. It so happens sometimes though that the disc cracks. This causes rattling noise and a flex plate that is difficult to engage with the starter motor. The only solution in this case is to replace the cracked flex plate with a new one.

Low oil pressure

When the oil pressure in the engine is low some of the components of the oil pump may not function. For instance, hydraulic valve filters and variable valve timing drivers will not function when there is insufficient oil pressure thereby leading to valve rattling. In addition to this, when the pressure of oil being pumped in the engine is low, the bearings become dry and wear out faster hence producing a rattling noise.

Piston Slap

In high mileage Volvos, wear and tear in pistons and cylinder head may be too high such that the pistons do not fit correctly anymore.  In such a case, you will hear a rattling noise when the engine is cold but as soon as it heats up, the noise goes away.  Piston slap is not only an annoyance but also a serious problem that requires an engine overhaul and piston replacement.

Worn Drive Belt

Since worm drive belts are made from rubber and fiber, they wear and degrade after a couple of hundred miles. This makes the belt to fall apart and at high speeds, the belt slaps around the engine thereby causing a rattling sound.  Replacement of a worn drive belt is easy and you can do it by yourself in your home workshop.

Engine Rattling When The Car Is Idle

The catalytic converter is the most likely culprit here. This is particularly common for older Volvo models as the wearing out of the converter leads to breaking off of chunks of the converter. To solve the problem, replace the faulty converter. Remember if not replaced on time, the converter can affect the smooth running of the engine.