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12 Jul 2019


100,000 kilometres is a reasonable distance for any car to travel.

Most of my colleagues have off-loaded their cars long before the odometer goes around the clock.

But my car is going fine and I’m still weighing up the energy options for whenever I finally trade it in (petrol, ethanol, diesel, LPG, hybrid, electric, hydrogen, nuclear etc).

After 10 years, my car is ready for some maintenance, particularly replacing parts that are made of rubber.

Fortunately my car has a timing chain rather than a rubber timing belt.

The chain should last the life of the engine.

But the air conditioning, alternator and sundry other peripherals on my car are all driven by a single serpentine belt which snakes around seven pulleys.

That belt is made from a synthetic compound called ethylene propylene diene monomer rubber (EPDM).

The same compound is used to make O-rings and seals.

Over time the belt wears and becomes shiny, cracked and prone to failure.

Far better to replace it now and throw the old belt in the boot as a spare.

Trying to find the right replacement belt was an interesting exercise in checking and cross-checking to make sure that I ordered exactly the right one.

My vehicle has electric power steering which saved one pulley and reduced the belt length by 15 centimetres.

So it was a 6DPK1698 belt that I needed.

6DPK referred to the six ribs on both sides of the belt and 1698 was the exact length in millimetres.

The multiple ribs reduce slippage and the fact that they are on both sides of the belt provides flexible stress relief so that the belt can be bent around pulleys in both directions.

New belts also have an additional stamp for the date of manufacture.

After all there is no point replacing an old belt, with an old belt.

My next challenge was how to get the used belt off?

I can honestly state that out of the 525 million hours of video on Youtube no one has posted a clip on my engine which shows exactly how to do it.

So it was with a lack of skill and experience I released the tensioner and delivered the old belt.

I then noticed that it was also a 6DPK1698.

The new belt should fit, I thought.

But there was another mark that really caught my eye.

It said that the old belt was made on the 14th of November 2009 in Germany by Continental.

Funny about that, because my car was assembled by BMW just six days later in Southern Bavaria.

And somewhere along the line the belt was fitted in the engine plant before the engine was fitted to my car.

These dates confirm that in the automotive world everything is made ‘Just in time’.

Pioneered by Toyota parts usually arrive at the factory on the same day that they are fitted on the assembly line.

No one keeps a large inventory which is costly to store and may not be used.

It’s all good until natural disasters, industrial action or some other unexpected event occurs.

That can see cars leaving the factory without a spare wheel etc.

I was very proud that I’d replaced the serpentine belt myself on my car.

So what did I do with the old belt?

I put it in the boot … ‘Just in case!’

Safe motoring,
Doctor Clive Fraser

Published: 12 Jul 2019