What is a Rod Bearing?
A Rod Bearing is made up of two halves of smooth metal that wraps around the connecting rod, and crankshaft. This design allows a very thin film of oil to be continuously pumped in between the pieces of metal to provide lubrication. The job of a Rod Bearing is to act as a fail-safe because the softer metal typically wears down and fails before the crankshaft or the rod itself. Both of those repairs are far more extensive and time-consuming if damaged from not replacing your rod bearings.
What Causes Engine Knock?
The rod knock in an engine can occur when the bearing has been partially or completely destroyed. It’s usually due to oil starvation although bearing wear can happen naturally over hundreds of thousands of miles.
On the flip side (literally) is the Wrist Pin. It’s a hollow pin that holds the piston to the top of the connecting rod. When there’s wear on the wrist pin, a condition known as “Piston Slap” occurs – the piston is slightly loose and wobbles in the cylinder, making extra noise.
Keep in mind that rod knock and piston slap are both caused by incredibly small changes in tolerances. We’re not talking about a quarter of an inch – we’re talking in terms of thousandths of an inch! That seemingly minor gap allows for enough movement to cause rod bearing noise because metal parts can now bang against each other.
The Rod Bearing Replacement Procedure
After the vehicle has been diagnosed our Certified Technicians begin the process of replacing the rod bearings. This process requires mechanical knowledge, skill, a clean workspace, and several specialist tools so we recommend leaving this job to the professionals at Bavarian Rennsport.
The oil is completely drained out as you would not want any old or already contaminated oil circulating within your new rod bearings.
A typical oil change in this engine is about 5 quarts while changing rod bearings a massive amount of oil which would typically never leave the engine.
We make sure to fill the vehicle back up to the appropriate operating amount.
Once the oil pan has been removed the technician will have access to examine the faulty or worn connecting rods/bearings and any other components within.
At this time we also recommend replacing the Motor Mounts if they are worn, as it will save you time and labor in the long run.
What Happens If Engine Sounds Are Ignored?
Like all problems with your vehicle, if they go on ignored it can turn into a bigger problem. Engine rod knock can and will turn into a much, much larger problem if not taken care of. Engine or rod knock will eventually evolve into a clatter as the bearing surface erodes over time. When the bearing has been annihilated – which doesn’t take very long – the bearing will weld itself to the crankshaft and the connecting rod flops around the crankshaft. If the connecting rod binds or jams, it can break away from the crankshaft, known as a thrown rod. While revolving around the engine at high rates of speeds it could blow a hole through your engine block.
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