It means Honda considers valve adjustments to be OPTIONAL: adjustments are
to be done only if the valves are adjudged to be noisy, the noise resulting
from naturally increasing clearances.
I'm not sure why Honda states it that way (as they generally have all
along), but valve clearance can /decrease/ as well as /increase/. You can't
hear decreased clearances.
Valve clearances change very little over the miles. In 24,000 miles you may
find one or two that have changed up or down by a thou, but not much more
change than that. My personal approach is to check the clearances every two
years regardless of what the valve chain sounds like, just in case.
"Ivory123" wrote in message
My 2010 Honda 2010 Owners Manual says: "Adjust the valves during
services A, B, 1, 2, or 3 if they are noisy."
I'm not certain if this suggests a mandatory valve adjustment during
service A or an optional valve adjustment during service A "if they
Never had a problem with any Honda I have owned. My 2006 I4 is still quiet
at 80k and the Prelude I had before never needed any adjustment before I
sold it at 68k. Only Honda I ever adjusted valves on was my 1970 CB 750 and
a Triumph Bonneville I owned before that. Years ago in the day of pushrod
engines -- Datsun 210 for example -- adjustment usually was needed on a
couple valves every 10-15k. I did check the valves on a 75 280Z I had every
10-12k miles with really no tolerance changes to speak of.
it's mealy-mouthed b.s. designed to minimize their obligations under any
warranty, but cover their ass if something goes wrong.
as pointed out by tegger, valve clearances can close as well as open -
only the latter leads to "noise", but the former can burn a valve and is
common if the vehicle is driven hard due to higher operating
temperatures. i would inspect and adjust as necessary every 30k, or
more frequent if driven fast or with heavy loads.
...which is exactly what Honda used to recommend before they became, as
you say, mealy-mouthed about it and hesitated to tell people that their
engines needed more/different attention than those of the competition.
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