Timing Chain Failure Symptoms

Diagnosing a Failing Timing Chain

Jake Mayock

Meet Jake

Jake is a founder of 8020 Media and TuningPro. He has over a decade of experience in the automotive industry including parts sales, writing, DIY modifications & repairs, and more. Jake is currently converting his N54 to a single turbo and building a Miata track car. He’s an experienced, hands-on automotive enthusiast who delivers in-depth, well-researched content.

Timing chains are an essential component to engine timing. For engines to function properly, the timing of the intake valve opening/closing, the combustion taking place, and the exhaust valve opening/closing must be precise. When things aren’t precise, a big problem arises which can lead to significant engine damage.

Properly maintaining a timing chain and being aware of signs of failure before it occurs is extremely important in preventing serious engine damage. In this guide we are going to discuss the functionality of the timing chain, signs and symptoms of failure, how to prevent it, and replacement costs.

Timing Chain Components

The timing chain is made of metal and turns on metal gears or sprockets, so it needs to be lubricated with oil. Therefore, the timing chain sits within a timing chain cover, which bolts up to the block and protects the timing chain from road dirt and debris while also lubricating it with engine oil.

Additionally, the timing chain also has timing chain guides, which help keep it on track and prevent it from slipping off of the sprockets.

The last important piece to timing chains is a tensioner. The timing chain tensioner makes sure there is no slack in the chain. Most tensioners are spring-based and hydraulically actuated, meaning they use oil pressure to keep the chain tight.

Here is an example of a timing chain system with the chain, guides, tensioners, sprockets, etc.

Timing Chain System

Causes of Timing Chain Failure

The primary cause of timing chain failure is timing chain stretch. Because the timing chain sits right near the block it is subject to lots of heat. Over time the heat causes the metal chain to slowly begin to stretch. At the chain stretches, it becomes loose on the gears and can then “jump teeth” or even completely fall off of the sprockets.

Additionally, timing chain stretch can be caused by low oil levels. Since the metal chain runs on metal gears, it creates heat and friction when not properly lubricated. When oil levels get too low the chain can be starved of lubrication which also causes it to stretch.

Tensioner Failure

Hydraulically actuated tensioners are known to fail due to low oil levels or oil pressure leaks. The tensioners use oil pressure to keep tension on the chain. When oil levels get low the oil pressure drops and therefore the tensioner doesn’t have the pressure it needs to keep the slack out of the line.

Guide Failure

Timing chain guides also commonly fail. The guides are usually manufactured of plastic which means they easily break over time from heat, engine vibration, etc.

When the guides fail, the chain gets off track and can jump teeth or completely fall off.

Symptoms of Timing Chain Failure

  • Cylinder misfires
  • Metal shavings in engine oil
  • Knocking or rattling noises from engine
  • Rough idling
  • Engine no start

When the timing chain stretches, jumps teeth, or completely fails, it causes the valves to open and close at the wrong times. If the chain just jumps a little then you will likely just notice rough idling, poor performance, misfires, etc.

However, if the chain jumps a lot or completely falls off the valves can go crashing into the pistons as there is nothing controlling the opening and closing of the valves. When this happens it can cause severe internal engine damage.

How to Prevent Failure

  1. Inspect your timing chain cover frequently for leaks
  2. Make sure engine oil levels don’t get low
  3. Don’t let the engine overheat; if it does, do not drive it

Replacement Costs

Most timing chain parts will only cost $100-$200. The most variable piece is labor. Labor typically ranges from $250-$1000, but it can be significantly more in some cases.

For example, the timing chain on Audi’s 4.2 V8 is located at the back of the engine requiring the whole engine to be pulled to be replaced. This leads to this being a $5k+ replacement job.

While that is an extreme example, the point is the cost to replace is predominantly driven by the difficulty of replacing it and not the cost of the parts themselves.

How Long do Timing Chains Last?

Most timing chains nowadays are manufactured to last the life of the engine, although, it is common for timing chains to go bad around the 150,000 mile mark.

Can I drive on a Bad Timing Chain?

You can drive on an old timing chain but we recommend replacing the chain immediately once you have noticeable stretch and symptoms of failure. If you drive for too long on a bad chain and it continues to stretch then it can jump a lot of teeth or completely fail and lead to catastrophic internal engine damage.

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