2004 Accord, 4-cyl -- Adjustable Valves?

Looks like wikipedia has a few words on hydrualic lifters and bucket-
shim:

History
The first firm to include hydraulic lifters in its design was Pierce-
Arrow in the early 1930s. Hydraulic lifters were popular on
automobiles designed in the 1980s, but most newer cars have reverted
to bucket-and-shim mechanical lifters. Although these do not run as
quietly and are not maintenance-free, they are cheaper and rarely need
adjustment because the wear caused by operation is spread over a large
area.[citation needed]

Disadvantages
There are a number of potential problems with hydraulic lifters.
Frequently, the valvetrain will rattle loudly on startup due to oil
draining from the lifters when the vehicle is parked. This is not
considered significant provided the noise disappears within a couple
of minutes, typically it usually only lasts a second or two. A rattle
that does not go away can indicate a blocked oil feed or that one or
more of the lifters has collapsed due to wear and is no longer opening
its valve fully. The affected lifter should be replaced in the latter
circumstances. In extremely rare circumstances, a lifter can "pump up"
and create negative valve clearance so that its valve cannot close.
This is more serious as burnt valves will result. In all cases it is
important to follow the manufacturer's recommendations for oil
viscosity and quality.[citation needed]

 

How can they go out of spec and become too tight?
Wear would rather make the gap to widen, not tighten over time...

 

Two kinds of wear:
1) Valves recede into seats; clearances CLOSE up.
2) Rubbing surfaces wear; clearances OPEN up.

Both kinds of wear happen normally to all engines, which is why provision
is made for adjustment, and why an inspection interval is specified in the
maintenance schedule.

 

Think of steel valves on softer aluminum seats.

-- Guess which one of the two is more expensive to fix?
A tight clearance leading to burnt valves (without enough time to
contact and transfer heat to the cylinder head).

-- And guess which one is quiet (and the other loud)?
Tight clearance
(loose clearance leads to ticking)

 

there's no seat that's aluminum. ever.

 

Right. Any aluminum head has hardened steel inserts for the valve seats.

Even many iron heads designed for unleaded gas have inserts.

 

Which process statistically wins in my accord 4-cyl engine?
When you adjust valves - which way they normally wear?

 

I believe if you check the maintenance schedule it will say something along
the lines of "check/adjust if noisy". That is probably a hint as to which
way Honda thinks they'll go.

 

depends how you drive. if the motor never gets hot, the gap will get
bigger - although it will take you forever to get there. if you're
average, it'll stay pretty close to neutral practically forever. and if
you habitually gun it, it'll close up. that's because the valves indent
a little when they run hot - the metal ever-so-slightly softens at
higher temperatures.

 

Goes either way, depending on who knows what. I'd say, statistically, there
is about a 50-50 chance of either wear manifestation, IF there is a change
at all.

For most of your valves most of the time there will be no apparent change
from one inspection to the next. But then one year you will find one or two
valves out of spec.

You still need to check them according to the schedule, since otherwise you
never know if anything has changed, what has changed, or which way the
change may happen.

 

Sam Bell of Motor Magazine's comments:

http://www.motor.com/magazine/pdfs/082007_09.pdf

"Some manufacturers, like Honda, now recommend adjustments only when
the valves are noisy. I question this advice, however, since my own
experience has shown that Honda valve clearances
tend to tighten rather than loosen as they wear, and are therefore
more likely to need adjustment when they’re quiet. In fact, I have
cured several complaints centered on poor fuel economy in Honda
products with just a good valve adjustment. Honda’s MAP-based fuel
strategy means that low engine vacuum resulting from poor breathing
will be mistaken for high engine loads."

 

i can tell you for fact, from direct personal experience, from running a
honda d-series zc cam, with higher lift and much longer duration than
any stock cam, that "breathing problems" due to tightened clearances is
complete and utter bullshit. the zc cam has those valves open way
longer than possible with a stock cam and merely maladjusted valves.

now, if the clearances are so tight that a valve is open all the time,
that's a different matter, but i can tell you again from direct personal
experience, that it's accompanied by valve burn-out.

lastly, honda doesn't measure load simply from vacuum [see the cam
situation above], but from what it knows it's injecting relative to
rpms. no "mistakes".

bottom line - this guy is badly underinformed and simply bullshitting.

 

You've yet to address whether valves tighten or loosen beyond
specification as they wear.

 

wrote in

It can happen either way. Personally, in my own experience, I see no bias
one way or the other.

In any case, it does not matter one way or the other. If they are to go out
of spec (and they will), you need to check them.

Why are you so concerned about which way they will wear? Are you trying to
avoid inspecting your own valves?

 

go back and check my post of 9/9.

 

I cannot tell why he is asking, but I was asking mostly from curiosity.
If this was true that the gap could only widen than you probably could
use audible clues instead of removing valve cover and using feeler gauge.

I have heard about some professional diagnostic tool which uses several
microphones strategically placed in the engine compartment and computer
calculating preciselly the sound direction and distance (3D) from the sound
born signal microphones generate.
This way they could pin point some bearing is going out before it happens
even somewhere deep in the engine or transmission just by listening to it.

I am not sure how this diagnostic device is called in pro world but if your
ears are as good than I guess you do not need to open the valve cover
to check the gap - you can tell something is wrong just by listening ))

 

What you describe may make sense if the vehicle in question is a Bugatti
Veyron, or a strip-mine dump truck costing a couple of mil, but for your
average consumer automobile, nobody's going to spend that kind of money.
Simply performing a valve check would be quite a LOT cheaper.

 

not to mention that even /with/ all that gear, you still can't actually
/measure/ a damned thing, as you need to do with valve lash.

 

Yes, you would not use this equipment for measuring valve clearance gap

Its main purpose was to diagnose premature wear in moving components
inside engines and transmissions. Opening up a transmission is not as easy
as taking off the valve cover

I wrote about it as an example of sound based diagnostic to make a point
about sound-diagnosing valves needing adjustment. Of course, again,
this would make sense only if the gap wear to be bigger not smaller...