Content
When buying a used car, few words cause as much dread as "timing replacement." This system is the heart of the engine's rhythm: if it fails, the result is a catastrophic breakdown.
In the used car market, like the one you find at AUTO.MOTO.pt, it is vital to know what is under the hood. Does your next car use a rubber belt or a metal chain? And why is this distinction crucial if you are looking for a BMW?
1. The Engine's Conductor: What is the Timing System?
To understand its importance, imagine an orchestra. The timing system is the conductor. Its function is to ensure perfect synchronization between the crankshaft (which moves the pistons) and the camshaft(s) (which open the valves).
The Analogy: If the conductor is a second late, the musicians (engine parts) lose the rhythm and crash into each other. In an engine, this means pistons hitting valves, turning the music into a very expensive silence.
2. Timing Belt: The Silent Standard
The most common solution in generalist brands is the timing belt (or toothed belt). Made of rubber reinforced with nylon, it is silent and efficient, but perishable.
Characteristics:
- Operation: Smooth with low friction.
- Maintenance: Mandatory and preventive. It gives no warning before snapping.
- Average Cost in Portugal: Between €250 and €800 (full kit with water pump).
Examples of Maintenance Intervals:
- Ford: Every 160,000 km or 10 years.
- Peugeot / Citroën: Generally every 120,000 km.
- Renault / Opel: Ranges between 90,000 km and 180,000 km, depending on the engine.
3. Timing Chain: The "Lifetime" Promise
Many premium manufacturers and some generalist brands (in specific engines) opt for the metal chain. The theory is attractive: a metal part designed to last the entire lifespan of the engine.
Theoretical Advantages:
- More robust.
- Eliminates mandatory scheduled replacement.
However, "lifetime" does not mean indestructible. Lack of maintenance (using incorrect oils) can lead to premature wear.
4. The Critical Case: BMW and the N47 Engine (118d, 318d, 320d)
BMW predominantly uses timing chains (engines N47, B48, B58). However, there is a technical track record that demands extra caution, specifically regarding the famous N47 diesel engine, which equipped a wide range of models between 2007 and 2014/15.
The most popular affected models include:
- BMW 1 Series: 118d, 120d, 123d.
- BMW 3 Series: 318d, 320d.
- BMW 5 Series: 518d, 520d.
The Problem: Stretching and Noise
Despite being a chain, it can suffer from stretching or excessive slack, frequently after 150,000 km or 170,000 km.
Warning Symptoms
If you are looking for a BMW 320d or 118d, pay close attention to the idle sound. The classic symptom is a metallic "rattling" noise (similar to dragging chains) coming from the rear of the engine.
Why is the repair so expensive? (€1,500 - €1,700)
Unlike a conventional engine where the timing system is at the front, in the N47 engine, BMW placed the chain at the rear of the block, next to the gearbox.
- Complexity: To change the chain, it is necessary to remove the engine from the car.
- Parts: The intervention often requires replacing sprockets, guides, tensioners, and even the oil pump.
Technical Note: Newer engines (B47, B48, B58) have significantly improved reliability, but maintenance with quality oil and at the correct intervals remains mandatory to avoid problems with the chain guides.
Conclusion: How to Make a Safe Deal
Whether it's a utility vehicle with a belt or a premium one with a chain, knowledge is key.
- Check the History: When browsing through the more than 8,000 ads on AUTO.MOTO.pt, always ask for the service book.
- Listen to the Engine: On a BMW N47 (118d, 318d, 320d), listen in silence (for example, in a closed garage without noise or at night). A metallic "rattle" is a sign that you should negotiate the price or look for another example.
- Sell with Transparency: If you are an owner and your car has up-to-date maintenance, this increases its value.
Want to sell your car? Remember that on our platform you can publish up to 2 free ads per month. Ensure your next deal is transparent, efficient, and without mechanical surprises.