BELT CLINICBEST PRACTICE

Guaranteed suppliesInstead of sourcing parts from a single partsmanufacturer, OE manufacturers oftencommission a range of component designsfrom different suppliers in order to guaranteesupply. For example, the OE tensioner for thetiming belt drives on a wide range of 1.6Ldiesel engines – as fitted to the VW Polo, forexample – are both supplied by Gates andLitens (this tensioner will also replace othertensioners in vehicles fitted to 1.6 and 2.0Lengines throughout the VW Audi group).

Both tensioners are OE designs. Theywere both developed to be compatible withthe drive systems in these vehicles. Thetensioners perform the same tasks. Theydeliver equivalent performances. The keydifferences between the timing belttensioners are that:

■ They do not look the same■ The installation procedures are different

Installer perceptionsMechanics who order Gates tensioners as partof a scheduled timing belt kit replacementhave been taken by surprise if the vehicle hasa Litens version. Similar reactions are to beexpected among mechanics who have found aGates tensioner when they were expecting tofind the Litens alternative.

It is important to realise that, in each case,the mechanic has a tensioner that wasdesigned specifically for the job.

Identification concernsTake a careful look at Fig 1. This is theDouble Eccentric tensioner supplied byLitens. Fig 2 is the OE tensioner designedand supplied for these engines by Gates. It isa Single Eccentric (off centre) design.

Note the locating tab in Fig 1. This is amajor difference between the two componentsthat raises significant concerns among manyinstallers. The Gates design has no such tab.

‘If there is no locating tab, it can’t beinstalled’, is popular myth number one.

Replacement procedures Many installers believe that the purpose of thetab is to lock the tensioner in place and preventmovement. In reality, the tab’s purpose is tolocate the tensioner and prevent back platerotation (left to right). If the back plate is unableto move, the tensioner could not work. Inpractice, it is vital that the back plate moves upand down, in the slot, as part of the installationprocedure. The tab guides movement.

MYTHBUSTING

12 JUNE 2017 PMM

When is an OE part modification not an OE

modification? When it’s an OE part supplied

by an alternative OE supplier, says Gates.

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