What’s driving water pump replacement?

Andrew Vaux, Training & Support Team, Gates UK offers his trio of drive systems technical tips.

Problems when the pump is up front

While all of the technicians at a recent Technical Workshop subscribed to the notion that belt kits should be fitted to all drive systems, some views implied that the Auxiliary Belt Drive System (ABDS), or front end drive, was considered to be of less critical concern than the timing belt drive. ABDS drives have become more complex and the number of drive system components has increased in recent years. For example, Torsional Vibration Dampers (TVD) and Overrunning Alternator Pulleys (OAPs) have been introduced to protect the multi-ribbed belt by absorbing vibrations and managing the various stresses and strains imposed by today’s high performance engines.

As such, these components are subject to wear and, in common with the belt, their overall performances decline with age. In addition to the alternator, key safety and comfort systems – power steering and the air conditioning – draw their power from the ABDS. Increasingly, it may also drive the water pump. This is true for about half of the vehicles on the market and especially so on a wide range of popular models, such as the Mercedes A150 1.5 (Petrol), Volkswagen Golf 1.4 (Petrol) and BMW 118d 2.0 (Diesel). Vauxhall/Opel and Renault are among many other manufacturers with similar drive system designs.

What's driving water pump replacement?Premature failure

An unexpected ABDS failure can have serious consequences – such as overheating of the engine or the sudden loss of power steering at a crucial time. There is also the very real possibility that debris generated in the destruction of the auxiliary belt might come loose and contaminate the timing belt drive. Those attending this particular Workshop heard that on a recent inspection, broken parts from the tensioner travelling at high speed had penetrated the timing belt cover, with devastating consequences for the engine. A more casual approach to ABDS maintenance can lead to catastrophic results. The inevitable conclusion is that issues with any one of the components in the ABDS very soon become issues for them all. Furthermore, it’s folly to expect a new component to integrate smoothly with a host of others that have been operating in tandem for the same amount of time as the part(s) about to be replaced. The beauty of an ABDS kit is that, if chosen carefully, it includes all of the parts required to overhaul the drive. Since the end of February a kit from the Micro-V® Kits with Water Pump range from Gates also includes the appropriate water pump for each application.

So if installing a belt kit makes sense, replacing the water pump is an absolute must in any drive belt drive system, especially for garages keen to avoid early comebacks. In the event of a complaint, the service provided by the garage will be measured against ‘good engineering practice’, which demands that all of the components in the ABDS should be replaced at the same time. Furthermore, ABDS kits that include a water pump give added value and protection for both the garage and the customer. The warranty for all of the parts is with the same supplier.

Water pump inspection checks

On inspection, a number of indicators may confirm a more urgent reason to change the water pump. These include:

  • Bleed marks around the weep hole, on the mounting surface or around the housing
  • Rust and corrosion on the pump surface and impeller fins
  • Cavitation – pock marks, play in the bearing
  • Evidence of bent or broken shaft

What's driving water pump replacement?

Reasons for premature failure include:

  • Poor installation
  • Contaminated/non compatible coolant
  • Improper use of sealant or gaskets
  • Bubbles in the coolant that burst under pressure – cavitation
  • Misaligned belt
  • Over-tensioned belt

VAG technical update

Changes to VAG 1.6 diesel CAYB & CAYC engines affect models equipped with air conditioning, from October 2009 onward. Classic multi-ribbed V-belts replace the earlier ‘elastic’ belts – a design that did not require a tensioner. For models from October 2009 onward, Gates recommends installation of belt 6PK1070, together with tensioner T38427.

Please note: the Gates range includes Stretch-Fit belts for all earlier applications that haven’t yet been adapted. Installation instructions and details about the correct tools required are printed on the inside sleeves and are also available from the online catalogue.

What's driving water pump replacement?

Quote me on that:

Water Pumps

According to ClickMechanic – the online job provision service for motor mechanics – water pump replacement tops the list of its most popular thermal management system job quotations. “With A/C category jobs we find that most people would prefer for the system to be checked and adjusted before they want a technician to actually embark on any repairs. After this, the most popular A/C jobs we see relate to servicing of the A/C condenser or compressor,” says ClickMechanic’s Kurt Schleier. “Taking into account the total number of quotes we give for each brand, we found that owners of high-end cars from brands like Mercedes-Benz and Jaguar are more likely to request these A/C jobs, with only Honda owners requesting more quotes,” he adds.

Water pump popularity Kurt continues: “As the heating and cooling systems on cars are usually inextricably linked, issues with thermal management can be complex. Interestingly, our most popular thermal management job is not an inspection, but rather a water pump replacement. This could suggest customers are confident of the exact issue on their cars and the need for replacements. “In all likelihood it means they will already have had their overheating problem checked, for example during a breakdown recovery of their car. There is also a clear seasonal aspect. In January, for example, car owners are far more likely to request quotes for heaterblower motors and heater matrix issues than in any other month.”

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