Timing Belt / Timing Chain

Keeps the crankshaft and camshaft(s) perfectly synchronized so that valves open and close at the correct time relative to piston position. Without proper timing, valves can collide with pistons (interference engine) causing catastrophic damage.

$500 – $2,000

Total Cost

60,000 – 100,000 miles (belt) / As needed (chain)

Replace Interval

Professional Only

DIY Difficulty

Do Not Drive

If It Fails

Overview

The timing belt or chain synchronizes the rotation of the crankshaft and camshaft, ensuring that engine valves open and close at precisely the right moments during the combustion cycle. Belts require periodic replacement; chains are designed to last the life of the engine but don't always.

Parts Cost

$100 – $500 (belt kit with water pump, tensioner, idler pulleys)

Labor Cost

$400 – $1,500

Failure Symptoms

Engine won't start or cranks but doesn't fire

Critical

Rattling or ticking noise from engine (chain)

High

Engine misfires

High

Metal shavings in oil (chain wear)

Critical

Check engine light with timing-related codes

High

Visible belt cracking or fraying

Critical

Warning Signs to Watch

Engine rattle on cold start (chain)
Visible cracking on timing belt (if inspectable)
Approaching or exceeding replacement interval (belt)
Oil leaks from the front of the engine near the timing cover

Common Causes of Failure

1Normal wear (belts are rubber and degrade over time)
2Oil contamination weakening the belt material
3Failed tensioner allowing belt/chain to skip
4Extended intervals beyond manufacturer recommendation
5Chain stretch from oil starvation or poor oil quality

Prevention Tips

Replace timing belts at the manufacturer-specified interval — don't push it
Always replace the water pump, tensioner, and idler pulleys with the belt
For timing chains, use the correct oil specification and change it on schedule
Listen for rattling on cold start — it may indicate chain stretch or tensioner failure

When to Replace

Timing belts: Replace at the manufacturer's interval — no exceptions. This is the single most important scheduled maintenance item. Timing chains: Replace if you hear rattling on startup, or if a mechanic diagnoses chain stretch or tensioner wear.

Timing Belt / Timing Chain by Make

Toyota

Most modern Toyotas use timing chains that rarely need service. The exception is the 2.4L 2AZ-FE (2002-2011) which uses a chain that can stretch.

Honda

Honda's V6 engines use timing belts that must be replaced every 105,000 miles. The 4-cylinder engines (2018+) use chains.

Volkswagen

Audi

The EA888 2.0T (2008-2014) has a notorious timing chain tensioner that can fail catastrophically. The chain is at the rear of the engine, requiring engine removal for service — a $3,000-$5,000 job.

Subaru

Subaru 2.5L engines use timing belts. Replace every 105,000 miles along with the water pump. The 2.0L FA20 (BRZ/86) uses a timing chain.

BMW

BMW N20/N26 4-cylinder turbo engines (2012-2016) have a known timing chain guide failure. Budget for preventive replacement around 80,000 miles.