Belt or chain?
The gearing connects the crankshaft (pistons) to the camshaft (valves). On most engines it is toothed belt or metal chain. Which one you have is written in the service book or we will tell you by brand and engine.
The strap is rubber and is changed periodically. The chain is designed to last longer, but over time it stretches and the guides and tensioner wear out.
When to change the belt
The interval is determined by the engine manufacturer - by kilometers or by years, which came first. It is most often between 60 000 and 120 000 km or 4–6 years, but for some engines it is shorter. The exact value is in the service book.
Years are as important as kilometers: the car may have been driven a little, but the tire ages and cracks.
- You bought a used car and you don't know when it was replaced — replace it
- The booklet interval is approaching
- There is an oil or antifreeze leak on the belt
- There is whistling or noise coming from the front of the engine
What is replaced along with the belt
The whole set is replaced, not just the belt: rollers and tensioner, and with many engines and the water pump, because it is driven by the same belt. A cheap roller bearing that jams breaks the new belt as well.
And the chain?
The chain does not have a fixed interval on most engines, but it is not "forever". Signs of a stretched chain:
- Rattling or rattling from the front of the engine for a few seconds after a cold start
- Error codes like P0016 — misalignment between crankshaft and camshaft
- Rough idle and loss of power
Changing the oil regularly with the right kind extends the life of the chain because the chain tensioner runs on oil pressure.
What happens if it breaks?
At the so-called interference engines — and these are most modern ones — pistons and valves occupy the same space at different times. If the gear breaks or jumps, the pistons hit the open valves. The result is bent valves, damaged valve seats, and sometimes pistons.
Then the head is removed and repaired: check for leaks, repair valve beds and valves, restore the sealing surface. We do all this in-house at our own grinding facility, but it costs a lot less to change gears in time.