Timing belt & water pump: indications of a defect

Recently updated on January 27, 2022 at 10:19 am

Water pump and timing belt: Functions and applications a closer look! How do timing belts and water pumps work, when should they be replaced and how can you identify a defect? These and similar questions are answered in the following article. Let's start with the simplest question: Why is there the water pump in the vehicle? The internal combustion engine generates heat that can have a detrimental effect on the engine and the components. For this reason, the engine must always be cooled. The heat generated must be passed on to the ambient air. The coolant is driven by a water pump. This allows the Circulation and heat exchange be ensured. The operating temperature is maintained and the motor is protected from overheating.

Different options for cooling a motor:

1. Oil Cooling
2. Water Cooling
3. air cooling

All three versions are used on modern vehicles with burner used. Water cooling is definitely one of the most important options.

Different types of water pumps

• electric water pumps
  An electrically powered water pump runs completely regardless of the engine speed. In order to achieve the desired operating temperature, the output can always be adapted to the cooling requirement. Electric pumps offer the advantage of being more efficient less fuel is consumed.
• mechanical water pumps
  Mechanically driven water pumps come with one Toothed belt or V-ribbed drive fitted. The speed is determined by the transmission ratio between the crankshaft drive wheel and the water pump wheel fixed coupled to the engine speed.

In modern vehicles, both water pump versions are used regardless of the structure of the engine.

How do timing belts work?

The timing belt is an integral part of many vehicles. It looks like a sturdy, large rubber band. Usually it is made of rubber. Inside, a timing belt has a number of teeth so that they can better grip the molded gears. Many timing belts have a high stability on. They are able to transmit more power than one fan belt. They prevent the belt from moving on the gears. If a toothed belt is damaged and no longer grip properly, it can slip and, in the worst case, damage the motor.

There are toothed belts between camshaft and crankshaft. It ensures that the valves open and close. As soon as it stops working properly, the valves hit the engine and can cause extremely high repair costs. It is therefore important that the timing belts undergo regular visual inspections. If necessary, they must be replaced. If the timing belt needs to be replaced, so should the Tension pulley and water pump change (all information on changing the timing belt). for more durability worry a stronger timing belt with matching pulleys and a better camshaft sprocket.

When should water pumps and toothed belts be replaced?

Notes on a defective water pump: An indication of a defective water pump can be a too high temperature of the engine and coolant. In addition, cooling water may have collected on the engine. This can happen if the hoses leak or the water pump and cylinder head gasket are damaged.

Improved seals are available for susceptible engines. There is more about this in our article "Indispensable: a good cylinder head gasket for the engine!". Too little coolant can also lead to damage. Therefore, the coolant level should be checked from time to time. There is more on this topic in our article "Everything you need to know about radiator antifreeze!". In the case of an electric water pump, parameters such as Speed ​​or delivery rate to be checked. These, too, sometimes lead to one Error message.

Indications of a defective toothed belt

Is the timing belt gerissen, the crankshaft continues to run, but the camshaft does not. Here it can happen that a piston meets a valve. This can damage the valve, piston, or motor. However, it can also happen that the valve, the camshaft or the cylinder head are bent, damaged or destroyed. A write-off from the engine and perhaps an economic total loss of the vehicle can result. Tip: In our post "Economic total loss! What is that, actually?“There is more information on this topic.

It should be absolutely avoided that the toothed belt tears. As soon as a toothed belt is stretched too much, it should be replaced immediately. Otherwise it could jump off and damage the engine. The engine may fail or stop working properly. Timing belts should therefore be checked regularly. As a rule, the timing belt must be in the period from 70.000 - 120.000 km be changed or if he is between 5 and 7 years ago old is.

What should be considered when buying?

If a new timing belt or a water pump (or both) is needed, a quality one should be high quality product (preferably OEM) can be bought. When buying, attention should be paid to a high level of customer satisfaction and a long shelf life. Both products should be manufactured to high standards. There are many well-known manufacturers who offer a timing belt set including a water pump for commercial vehicles and cars as a set (Water pump, toothed belt, tension pulley). Before a repair should discord Refer to the vehicle owner's manual for component maintenance. This gives you more information. Repairs and installation should only be carried out by qualified personnel with suitable tools. This ensures that all components function properly.

Water pump / coolant pump defective - symptoms, repair / replacement summary information:

• the water pump is also known as coolant pump, cooling water pump, cooling liquid pump
• the water pump ensures that the cooling water is continuously pumped through the circuit. The water absorbs the new heat and transports it away.
• Defective water pump means that the engine is no longer adequately cooled (the result is overheating and there is a risk of engine damage)
• Symptoms / signs of the defective water pump / coolant pump
  - Loss of cooling water (stains / puddles of cooling water under the vehicle)
  - The engine temperature rises enormously (the coolant temperature display in the instrument cluster rises and a warning via the on-board computer may sound)
  - The fan temperature rises
  - strange noises when the engine is active
  - Heating does not work (if there is no more cooling water circulating)
• Causes of the defective water pump / coolant pump
  - worn seals
  - Pump / impeller inside the pump is defective
  - electrically driven water pump has a defect in the electric motor
• A defective bearing of a water pump that is driven by the toothed belt can be knocked out, so the toothed belt does not run properly and can hit the outer leading edges, wear out and even tear. Engine damage can result.
• Continue with a defective water pump / coolant pump no way
• Mixing up a defective water pump
  - If the main symptom is loss of cooling water, a defective thermostat or a defective radiator fan can also be to blame.
• Repair or replacement of the water pump or coolant pump
  - Special tools are often required
  - mechanical water pump -> the belt drive must first be removed. Then the pump can be removed and replaced. Then fill in new cooling water and take a test drive.
  - electric / map-controlled water pump -> no dismantling of the belt drive required. After the replacement, fill in cooling water and take a test drive.
• Cost of replacing the water pump
  - Material costs between 30 and 350 euros (Mapco, Valeo, Bosch, SKF, Meyle)
  - If a mechanical water pump is replaced, the toothed belt / V-belt and the seals should also be replaced
  - Cooling water, depending on the engine, 3 to 5 liters are required (8 to 10 euros per liter)
  - Working time between one and four hours (labor costs from 60 to 360 euros)
  - Total costs of around 90 to 800 euros.

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