5 Signs of Defective Connecting Rods

5 Signs of Defective Connecting Rods

A connecting rod is an essential component of every engine. The connecting rod is attached to the piston on its small end and to the crankshaft at the big end. The rod's big end rotates with the crankshaft and the small end reciprocates with the piston's wrist pin. Thus the conrod transforms the piston’s reciprocating motion to rotational motion of the crankshaft.

An engine may eventually be catastrophically damaged by a defective or damaged connecting rod. A failed connecting rod is one of the most catastrophic varieties of engine failure. This failure is generally called a "thrown rod" or "throwing a rod". When a connecting rod fails, the piston or connecting rod has a high probability of slamming into the engine block at high speeds, destroying anything in its path.

Although we cannot easily detect whether our engines have a flawed connecting rod, here's a list of signs of a faulty connecting rod. 


1. Low Engine Oil

If your connecting rod is damaged or deteriorating, your engine will likely lose a large amount of oil very quickly, causing your engine's oil pressure to drop.

Your engine may have an oil pressure gauge that can alert you when the oil pressure is low. In addition, your dashboard most likely has a caution light that will inform you as well.

If your oil pressure is low, it signifies your engine's oil isn't circulating properly. If the problem is not handled quickly, the engine may overheat. You will notice significantly more wear and tear since the working surfaces not be appropriately oiled and can result in irreparable damage.

This is caused due to worn out conrod bearings which throw excessive oil up toward the piston, thus overwhelming the piston rings which are designed to scrape off a nominal amount of lubricating oil off the liner wall. This may also cause oil to enter the combustion chamber thus increasing oil consumption dramatically and causing its level to be perpetually low.


2. Excessive Oil Consumption

For the same reason explained above, worn out conrod bearings increase the rate at which the engine consumes oil. As a result, the engine's oil levels will always be low. Check to see whether the engine is using too much oil.

The current oil will need to be replaced more frequently than usual. Additionally, it will raise the expense of operating your automobile, boat, or machine.


3. Engine Knocking Sounds

When you start the engine, listen for a knocking sound to see if your connecting rod is faulty. When the engine is still cold, the noise will usually be louder. It is referred to as "rod knock" informally. The hollow rod knocking vibration will increase in frequency as the engine's RPM rises.

The noises may fade after a short time once your oil has had a chance to circulate and lubricate the engine components.


4. Visibly Bent or Damaged Rod

If you suspect you have a bent or damaged connecting rod based on the other symptoms you're experiencing, you should physically inspect the rod to determine its condition. This would necessitate disassembling your engine, which is a job best left to an experienced mechanic.

The mechanic will examine the connecting rod, bearings, and crankshaft. This is a costly prospect, but a faulty connecting rod will necessitate a complete engine rebuild in any case.


5. Seized Engine

A thrown rod is likely to cause the engine to stall and seize. When you can't turn the engine by hand, or using a wrench on the crankshaft pulley bolt, you know, it's seized, since even an engine unable to start can usually be cranked manually as long as it has not seized.

A loud bang and metal flying out of the engine block are telltale signs of a fractured rod. After this occurs, you may observe a large puddle of oil under the car, as well as a large hole in the block.

Connecting rods fail rarely, and most of the times they fail due to other reasons like bad quality of engine oil, or oil filter not changed at the specified service interval, which causes metal chips in the oil to wear out the conrod bearings prematurely. When they do fail, they need to be changed immediately if you notice any of the symptoms mentioned above, as their failure can lead to very expensive engine overhaul and downtime costs.


Garima Global exports high quality connecting rods globally. Our connecting rods are tested thoroughly after the manufacturing process to ensure that they will not fail in the field, ensuring our customers to become the go-to source for connecting rods in their respective markets. This makes Garima Global one of the leading exporters and suppliers of connecting rods in India.


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