Preamble
Are you the ‘lucky’ car owner with a belt-in-oil system?
If the answer is YES, read on and see how to avoid finding yourself in an unpleasant and expensive situation!
If the answer is NO, stay away from this type of car! You have been warned!
Types of timing belts
The timing belt is a critical element in the operation of internal combustion engines and, therefore, needs careful maintenance. We often also hear of the timing chain. The only difference between a timing belt and a chain is that the timing chain is metallic and lasts longer than a timing belt. These two types of components serve the same purpose: they are used to synchronise the camshaft and crankshaft rotation system, allowing the valves to open and close at the right time.
These car parts are subjected to great strain, so the timing belt usually requires replacement at some point. The car’s engine cannot run properly without a perfectly functioning timing belt/chain.
The timing belt exists in two variants: the dry timing belt, which is positioned outside the engine crankcase, and the wet timing belt or belt-in-oil when the timing belt is fully encased within the engine. The wet timing belt system was introduced over 15 years ago or so by manufacturers like Ford, PSA(now a part of Stellantis) and VW.
This timing belt-in-oil system was introduced for the following reasons:
– longer maintenance intervals due to the oil lubrication: the timing belt is constantly lubricated by the engine oil, which means that it reduces friction and wear, extending the life of the belt and reducing fuel consumption and CO2 emissions;
– cooling: the oil helps dissipate the heat generated by the timing belt during operation, contributing to better temperature management;
–noise reduction: the oil can dampen vibrations and reduce noise generated by the movement of the timing belt, leading to quieter engine operation.
On paper, it looked like an excellent system; too bad that, in real life, the situation is completely different!
Even small impurities, such as soot particles and crystalline compounds in the engine and oil, lead to premature belt wear, resulting in material detaching that clogs the oil sump filter and produces oil starvation. The brake vacuum pump can also be affected by the detachment of material from the timing belt, with the risk of an accident.
Warning signs that tell you it is time to replace the timing belt
The timing belt replacement interval is written in the owner’s manual for cars with dry belts, but you must consider the type of driving, whether under normal or severe conditions. Remember that if you drive in severe conditions, the service intervals should also be shortened according to the manufacturer’s instructions to avoid breakdowns and high bills.
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Some signs can help you realise that your dry timing belt is having problems
Before we get to that, however, it is important to remember that prevention is the key to optimal car maintenance, as there are not always sure signs that the belt is close to breaking.
- High-Pitched Whining Noise: One of the earliest signs of a worn-out timing belt is a high-pitched, whining noise coming from the engine. This noise can start as a faint squeak and gradually become more pronounced as the belt deteriorates. If you hear this sound, it clearly indicates that the timing belt may be nearing the end of its life.
- Ticking or Clicking Sounds: A failing timing belt may sometimes produce a ticking or clicking sound as it rubs against other engine components. This noise can be particularly noticeable when you start the car or accelerate. Ignoring this symptom could result in severe engine damage.
- Rough Idling or Misfires: A worn timing belt can cause the engine’s timing to err. This can lead to rough idling or misfires, which may feel like the engine is vibrating or hesitating when you’re at a stop or driving at low speeds. These performance issues are often indicative of a timing belt problem.
- Reduced Engine Performance: If your car experiences a noticeable drop in power and acceleration, it could be due to a compromised timing belt. When the timing is off, the engine’s performance is compromised, decreasing power and efficiency.
- Oil or Coolant Leaks: A damaged timing belt cover can lead to oil or coolant leaks. If you notice puddles of oil or coolant under your car, it’s essential to have the source of the leak inspected promptly. Addressing this issue early can prevent further damage to the timing belt and engine.
- Engine Overheating: A failing timing belt can disrupt the cooling system’s operation, leading to engine overheating. If you see the temperature gauge climbing into the red zone or experience frequent overheating, it’s critical to have your timing belt checked immediately.
- Visible Wear and Tear: Periodically inspect your timing belt for visible signs of wear, such as cracks, fraying, or missing teeth. If you notice any damage or signs of deterioration, it’s time for a replacement, even if the symptoms mentioned above are not yet present.
When replacing a wet timing belt
There are no apparent signs to detect problems with the oil bath belt. However, if the wet belt is worn, the engine may have difficulty starting or run poorly at idle and operate erratically at high speeds.
Although wet belts are less prone to breaking, their teeth can come loose. Even if a belt is severely weakened, it continues to function, but the fibrous debris that detaches from it can seep into the oil pump strainer, causing a loss of oil pressure, activating the limp mode and the warning low oil pressure light coming on the dash.
Vehicles that mainly run low mileage and are driven mainly in cities with start-and-stop traffic often fail to expel moisture and fuel residue from the crankcase, as they rarely reach the standard operating temperature. As the oil degrades, its acidity levels increase, adversely affecting the wet belt properties.
Now, a real situation of a wet timing belt
A Peugeot 3008 1.2L 2017 petrol engine, running in limp mode with the low oil pressure warning light after only 40,000 miles.
Fibrous debris from the wet belt clogged the oil pump filter, causing the oil starvation and the oil pressure warning light on the dashboard to come on.
What to do
In the case of a dry timing belt,
the situation is much simpler. If you hear strange noises, which may indicate that the timing belt needs to be replaced, you should take the car to the workshop. You should not continue to drive a car with a worn belt. You risk damaging the engine.
What about a wet timing belt?
Operating with insufficient oil levels, neglecting regular maintenance, or using improper oil in engines equipped with timing belt-in-oil systems could harm the longevity of the ‘wet belt.’ Therefore, the engine oil’s quality, specification, and cleanliness become crucial factors.
Given our experience, we recommend drastically shortening the oil and belt change intervals for cars with a belt-in-oil system. We also recommend checking the wear condition of the belt every two years for added safety.
The belt should be replaced sooner if a vehicle covers fewer than 10,000 miles per year, particularly with most journeys being shorter than six miles. Additionally, it is imperative to ensure that the correct oil, compliant with the manufacturer’s specifications, is used during servicing. Different timing belt lubricants may contain chemicals that could potentially harm the belt, making it paramount to prioritise the manufacturer’s recommended specifications.
Warning! If the engine pressure oil warning light comes on, stop the car immediately in a safe place and tow it to a mechanic. Do not restart the vehicle; you could irreparably damage the engine!
To summarise:
- never, under any circumstances, skip scheduled maintenance;
- only use the type of oil specified by the manufacturer;
- occasionally check the oil level and top up if necessary;
- if you drive the car under severe conditions(see the owner’s manual), shorten the scheduled maintenance intervals, oil changes and belt replacement intervals.
