Is Your Engine Rod Knocking? Engine Rod Repair Cost

If you hear a knocking sound coming from under your car hood, it may be rod knock. Find out what it is, what causes it, and the repair cost estimate. It's better to tackle it early than to pay a fortune later.

– Knock-knock –
– Who’s there? –
– The Engine –

Seriously, if you hear a knocking sound coming from under your hood, it is definitely not a reason to joke around.

What causes an engine to make a knocking sound, and what should you do about it?

It may be rod knock!

This occurs when the crankshaft journal (which connects the crankshaft to the connecting rod of each cylinder) and bearing collide, which can create a knocking sound. If ignored, rod knock will progressively get worse, causing more damage and, therefore, a higher repair bill.

Thankfully, in this handy guide, we will cover everything you need to know about rod knock. Let us start by examining what exactly rod knock is

Following that, we will examine the reasons behind rod knock and the estimated cost of repairs to address it.

Let’s get started with the basics!

Table of ContentsShow

Rod Knock? What Is That?

engine crankshaft

An engine makes power by creating tiny explosions inside a series of cylinders (similar to the barrel of a gun). Inside each is what is known as a piston.

A piston is a plunger-like component that moves up and down from the force of these explosions.

Each piston is connected to the crankshaft through a connecting rod. A crankshaft is a rotating shaft that converts the back-and-forth motion of the pistons into rotational motion. So as the pistons pump, the crankshaft spins, propelling your vehicle forward.

Rod knock occurs when the crankshaft journal (which connects the crankshaft to the connecting rod of each cylinder) and bearing collide.

Basically, the connecting point between the two has too much play, and there’s too much space between the metal. When this collision occurs, it makes a knocking sound.

Since it knocks at each rotation, the higher your engine RPMs are, the faster the knocking will be.

What Causes Rod Knock?

connecting rod bearing

The most common cause of rod knock is a spun bearing, which is when the rod bearing essentially jams up.

This causes the gap inside to expand so that every time it goes around the excess play creates a knocking sound.

What triggers a twisted bearing? There are numerous possibilities, which encompass:

  • A lack of lubrication
  • Particles in the oil
  • Loss of oil pressure
  • High operating loads
  • Excessive heat

A few ways to protect your engine rod from knocking include regularly changing your oil and spark plugs and only filling up at Top Tier gas stations.

Let off the gas immediately if you ever hear a pinging or knocking sound.

How Much Are Engine Rod Repair Costs?

auto pistons and connecting rods

The cost to repair an engine rod knock depends on several factors, including:

  • How long it’s been knocking
  • The extent of the damage
  • If it’s a high-performance engine
  • If the engine is salvageable

The last thing you want is to find out your engine needs to be rebuilt, which can cost between $2,500-$4,000. Or worse, a total engine replacement, which can reach as high as $10,000 or more.

How much does it cost to repair engine rods? Typically, it will cost about $2,000 to $3,000 for the parts and labor. The repair job typically requires replacing seals, gaskets, connecting rod bearings, and cylinder head bolts, as well as flushing the engine and cooler lines.

Though, if the damage is worse, you may need to replace some extra parts, like the pistons, connecting rods, camshaft bearings, timings chains, and perhaps even the crankshaft.

Our Advice? Don’t Wait

The longer you wait, the worse things will be.

Regardless, it’s a costly repair, no matter how you slice it. However, tackling it early, rather than waiting, can quickly become the difference between whether a repair is possible, or if you need a new engine.

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Joshua Barrett

Josh Barrett is a writer hailing from the great state of Alaska. While describing himself in the third person is not his forte, writing about any and all things automotive – is. After 13+ years hustling in the exciting world of car sales, he took off to travel the world with his dog Teemo.