"Steve B." <none@[EMAIL PROTECTED]
> wrote in message
news:dfc024p5gir664igngbcmvk7kcdj90nuji@[EMAIL PROTECTED]
>
>>
>>First of all, what's an "interference engine"? I've never heard that
term
>>before.
>
> www.google.com
Ah. I'd never heard that term before. I see the difference:
http://www.gates.com/brochure.cfm?brochure=2256&location_id=3487&go=SearchGatesPopular
has diagrams which show how for a non-interference engine, the valves and
piston never occupy the same space whereas for an interference engine they
overlap though never at the same time! I'd thought that *all* engines were
interference type.
>>On a related note, I'd like to know how a garage can examine my fan-belt
>>(well, alternator and power-steering belt) amongst other things at a
>>service, and mark it as "visually checked - OK", and yet the belt breaks
>>one
>>week later... Surely the reason for visually checking a belt is to
detect
>>imminent failure *before* it happens, to avoid stranding me in the
middle
>>of
>>nowhere late at night, requiring me to be towed home. To add insult to
>>injury, the replaced belt broke one month later because there had been
>>undiagnosed damage to the crankshaft pulley that hadn't been picked up
>>when
>>the belt and idler pulley were replaced :-( The garage reluctantly made
a
>>goodwill payment of a mere £20 - less than a tenth of the cost of the
belt
>>replacement.
>>
>
> Belts often look "good" and fail. That is why belts have a prescribed
> change interval. Yours is a perfect case of "something else failed".
> In your case the belt probably did look fine, the crankshaft pulley
> was damaged and chewed hell out of the old belt pretty quickly.
Interestingly the belt split lengthways, with only half the width breaking
in two. So the belt didn't just fall off into the road and was still there
to be examined when I stopped the car. The ridges that engage with the
crank, alternator and power steering pulleys had tiny cracks across them
every millimetre or so, as if the rubber had perished. It was the idler
pulley rather than the crank pulley which was damaged on the first
occasion:
it looked as if it had ****fted sideways on its shaft and scraped against
the
engine housing.
Mind you, as far as I know, the belt had never previously been changed at
a
service - and the car had done 120 K miles. I wonder if it should have
been
replaced every so often.
> The
> new belt lasted a bit longer just because it was new before the same
> damaged pulley got it. A damaged crank pulley is a pretty rare thing
> so the shop didn't notice the damage (on some cars you can hardly even
> see the crank pulley from above). Crappy situation but it happens.
Yes. When it happened the second time, I'd driven a long way the day
before
without any problem, then within a mileor so of setting off on a long
journey the next day there was a clattering chugging noise (I thought
there
was a tractor behind me!). This seemed to get worse whenever I came off
the
power. I limped back home again, with the ignition light occasionally
fla****ng on (a sure sign that the belt had problems) and as I turned into
the drive, the noise became much louder. The belt was intact but looked as
if it was covered in very viscous oil - my first thought was than the
crank
pulley bearing had gone and engine oil was leaking out, which would have
been expensive! It seems that the viscous black goo was molten rubber from
the belt.
A nice little bill - an extra £250 that I hadn't bargained for, on top of
the previous bill for this amount when the belt failed the first time.
As a matter of interest, while the belt is off before it is replaced, how
easy is it to tell whether the crank pulley is damaged? Would it wobble
from
side to side on its shaft? I'm assuming that the ridged surface of the
pulley was undamaged because surely a garage would spot that as they were
fitting the new belt, even if they didn't notice that the pulley was loose
on its shaft.
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