last weekend, i did some work on a friend's 89 civic. it turned out,
the timing belt hadn't been changed in 262k miles. yup, you read that
right, it was >150k miles and >15 years over schedule.
not only did he have the full service history from new, he'd driven it
for 150k of that and could personally vouch for his portion. so when i
took the timing cover off, i was looking particularly for any evidence
of prior change. nothing. the tensioner bolt still had its original
paint seal intact, and you can't change the belt without slacking the
tensioner. nor did the crank pulley bolt show any signs of ever being
wrenched - they always get stuck and need some serious impact driving to
remove which always leaves evidence.
so, while it's best to stick to the factory service schedule, honda were
apparently quite conservative with their components back in the late 80's.
i have the old belt as a souvenir. it's got the older style label
graphics of the era. the only other discernible difference between that
and a 7-year old 120k mile belt from one of my hondas is that the high
mileage one is noticeably more flexible - i'm guessing because honda
changed cordage some time in the 90's,
oh, and i checked the coolant pump. still in great condition, so i left
it on there. same for the seals. something to think about next time
you're forking out $600-$800 for a belt/pump/seal change and get to
wondering what exactly is specified in the honda service schedule vs.
what seems to unquestioningly have been accepted by the public as "stuff
you always pay for".