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Those of us of a certain age will remember that in days of yore, ones camshaft – or camshafts if one was really into exotica – were almost invariably rotated by means of a chain drive from the crankshaft. Those timing chain drives were frequently noisy, as the chain wore & stretched, but almost always reliable. If nothing else, they gave plenty of highly audible warning of their impending demise!
The great gods of automotive progress then decreed that what we really needed were nice quiet belt drives, and so we were all treated to, and marvelled at, how quiet these drives were, coming from a background of, for example, BMC ‘A’ and ‘B’ series motors where a worn timing chain could be heard a mile away! Indeed, I recall in my long-distant days as an impecunious apprentice at BMC Longbridge running a Mini with a chain worn and flapping to the extent that it wore a hole through the pressed steel timing case. It still didn’t fail though, even though on strip down much of the teeth on the gears had also been worn away.
In fairness to the car manufacturers, though, the lengths of timing chains and belts had increased dramatically, as the once-conventional single camshaft located at the side of the engine gave way to single or, increasingly, twin overhead camshafts in the interests of performance and efficiency.
Even in those far-distant days, though, we saw the downside of these belt drives, in that the belts were a scheduled service replacement item at some considerable expense. Any thought of turning a blind eye to the need for this regular replacement was soon tempered by the realisation that belt failure would in many cases result in terminal failure of ones engine, as the then-unconstrained valves attempted to fight the pistons, with dire consequences.
Matters were then made worse by the insidious ‘Value Engineering’ techniques adopted by the car manufacturers to shave off a few coppers from the manufacturing cost of the engine by using plastic parts for timing pulleys and other items. If these items were not also changed with equal regularity to the belt they too could self-destruct without warning, leaving ones engine an expensive pile of scrap metal. Probably the most memorable of these was the Vauxhall Cavalier/Vectra, although this GM product was by no means the only offender.
Small wonder therefore that several respected car journalists began to warn against the perils of buying cars with timing belts (and by extension plastic pulleys), strongly advocating that one consider buying a car with a timing chain instead.
Never one to miss a trick, in the light of this publicity, the manufacturers then started to reintroduce timing chains rather than belts, proclaiming the virtues of eliminated maintenance and so forth. Unfortunately, in many cases they perpetrated the use of low-quality plastic parts such as tensioners and gears within the timing chain arrangements, thus storing up problems for the future. Sadly, this was exacerbated by another so-called automotive advancement in the use of extended oil drain intervals. The regular annual or even 6-monthly oil change gave way to 2-year oil changes, or even more in some instances. Manufacturers argued strongly that this was possible due to improved oil technology, which meant that the oil quality did not degrade with age to the same degree as before.
Unfortunately, this ignored (in my humble view) one of the fundamental reasons for having oil in the sump at all: to hold in fairly harmless suspension those combustion products (i.e. carbon) which find their way past the piston rings and into the engine oil. Only the biggest of these by-product particles are trapped by the engine oil filter, the rest are held in the oil and eventually form a fine grinding-paste. The longer the engine is run without an oil change, the more particles are present and the more aggressive the grinding paste becomes!
The list of manufacturers suffering timing-chain-related issues is legion, to name but two.
Here endeth the history lesson, and fast forward to the last few days. My pride and joy is a John Cooper Works Mini, which, whilst not in the first flush of youth should still be capable of providing many, many more miles of fun. A couple of times over the last few weeks however, she has sounded on the first start of the day more like a life expired diesel than a hot hatch. Suspecting that this noise could be timing-chain-related, I sought the aid of t’ interweb, which duly flagged up horror story after horror story of ‘death rattles’, not just on Minis but a range of other cars as well including BMW, Peugeot & Saab, all of which enjoyed, if that’s the right word, timing chains rather than belts.
The Mini was therefore duly booked into my local Mini dealer, Barons of Hindhead, and I was pleased to be advised that they could subject the car to a very precise and reasonably priced diagnostic procedure to pinpoint the source of the noise and identify how much remedial action may be required. This could range from simply replacing the tensioner up to the ‘Full Monte’ of replacing not just the tensioner but also the chain and guides.
The next day Angus at Barons called me, apologetically, to break the news that the diagnostics had unfortunately shown that the chain was outside tolerance and needed replacement. The cost – £1,035 sir.
Having picked myself up of the floor, I asked whether any financial support from Mini might be forthcoming towards this cost, since the car had always been serviced within the Mini dealer network and had only done a low mileage. “Sorry sir”, the answer came back, “Mini normally only provide out-of warranty support up to 5 years”. However, they did offer to approach Mini on my behalf, whilst at the same time organising the parts to do the repair.
It wasn’t too long before Angus was back on the phone with the welcome news that Mini had agreed to pay for all the parts and 50% of the labour, reducing a £1,000 plus possible bill to a shade over £400. So well done Barons of Hindhead, and well done Mini for stepping up to the plate – even though it would have been nice not to have had the problem in the first place.
And lessons learned for the future?
Well, number one must be to insist on at least annual oil changes for any car – the service indicator on the Mini would I’m certain have gone to 3 years if I had not taken pity on it after 2 years. And number two? Maybe belt drives are not so bad after all: the amount of cash I’ve had to fork out to fix my timing chain was after all pretty much the same as a routine belt change at a similar age and mileage would have cost. And belts are certainly a lot quieter!