What is this ticking noise?

I have a '92 Honda Civic EX with 156k miles. It runs fine and doesn't
give me any problems. The oil was changed about 500 miles back.

I hear this very fast ticking noise on about the first five blocks in
the morning. Then it stops. It's coming from the motor and some one
else probably wouldn't notice unless I pointed it out.

When I start the car, it idles at about 1500 RPMs. About three or so
minutes later, it is at around 1100 or 1000 around five minutes. Now
if I take off, I don't hear this noise. I imagine the noise is the
engine turning at higher RPMs because the oil has not heated up yet and
it takes more effort to turn the cam. Once the motor heats up,
everything is well lubricated, hot and so it runs very smooth. But
what could this noise be?

Also, do I actually need to wait until the car idles down to 1100 RPMs
each morning? I've read that about 30 seconds of warm up time is just
fine. My car is just below 1500 RPMs at 30 seconds. To me, that
doesn't show it has warmed up at all. What's the general concensus on
this?

Thanks,
Brett

 

Sounds like the valve lash (distance between rocker arms and
valve stems) is set a bit on the high end of the spec. This
is very common. It's better to be on the high end of the
spec than the low end--too small a clearance can cause valve
damage, IIRC. Googling will yield some discussion of this.

You hear it first thing because the valve parts are not
warmed up and so are relatively contracted. As they warm,
they expand, and that clearance reduces.

Check your manual's maintenance schedule for how often the
valve lash is supposed to be checked (and so possibly
adjusted). Though I ignored my 91 Civic's for 150k miles
(out of ignorance), then checked it. All was fine. But don't
do as I did. It is risky. Valve damage is expensive. I got
lucky.

I think that's because, when accelerating quickly while the
engine is still pretty cold, the higher RPM makes the
ticking harder to detect. The rate of valve opening and
closing will depend on RPM, after all.

I've read the same. Only in the rare times the temperature
has been below 10 degrees F have I ran out and warmed up my
91 Civic for five-to-ten minutes. I don't know if that's
necessary, even in really cold weather.

My Civic is doing fine after 14 years and 172k miles, over
half of which were driven in the Northern U.S., with its
abysmally cold winters.

 

So how long do you usually let your car warm-up during the various
seasons?

I guess the conclusion is that it is much better to allow the engine to
idle down. This way, you elimate all valve lash and probably a few
other things you weren't aware of. Do you agree?

Thanks,
Brett

 

I live out west in a much milder climate now. Lows in winter
during the day are, at the very worst, around 25 F. And
that's rare. Also, I have a garage. So these days I never
purposely let my Civic sit and warm up upon leaving my
house.

When I go into the mountains to ski, and the car is exposed
to the elements and extreme cold (teens or worse, degrees
F), sometimes I'll give it a minute or so, tops. I don't
know if that's really necessary. (If there's a sheet of ice
built up on my car, that's different, but that's of course a
special situation and not really your main concern, I
think.)

No, I don't think that's necessary at all. The engine
control system senses several parameters (air temp, coolant
temp, etc.) and deals with the car being cool. The engine is
tough enough to take it, IMO. I don't think one will squeeze
more life out of one's car by letting it sit a few minutes,
idling in the driveway, before leaving. Engine oils are
better than they were a few decades ago, as well. (Certainly
synthetic is a vast improvement! I don't use synthetic, but
I would if my car were new or just had its oil lube system
thoroughly cleaned. Not that anyone bothers with the
latter.)

At most, by warming up the car first, I figure one's muffler
might last longer. They rust prematurely when one goes on
only short trips, as you probably know, not allowing
sufficient heating to evaporate away accumulated
condensation in the exhaust system.

One is more likely to eliminate all tapping, perhaps. But
again, I don't think a little tapping is going to affect the
valves' life by much at all. I base this on reading about it
on the web. People generally say get it in spec, and better
to tap a little than not at all.

Off the top of my head, I don't know whether eliminating
/all/ the valve stem-rocker arm clearance at normal engine
operating temperatures is desirable or by design.

No. The engine control system (and thermostat) senses yada
yada (see above) and adjusts fuel flow, coolant flow, and
RPM etc. so as to achieve ideal conditions in a reasonable
amount of time.

Also, I think the engine valve design is plenty tough enough
to deal with a bit of tapping, as long as the lash is still
in spec. (Else the spec for the lash would be more
exacting.)

Keep checking back. Many of the regulars are busy during the
day and do not get to the group until later.

 

At normal op temps, it does idle lower, like 750 RPM,
doesn't it?

The normal operating idle RPM will vary by car model and
year, but I would think your 92 Civic EX normal operating
idle RPM was closer to my 91 Civic's (about 750 RPM, for a
1.5 L engine).

 

It drops below 1000 when I put it in gear. Yes, probably 750 perhaps a
little lower.

Thanks,
Brett

 

valves ever been adjusted? thats a start. another possibility is "piston
slap" which is not harmful, just an annoyance.

 

I haven't had the valves adjusted but it sounds as though I can go
until the car is sold (200k?) without any problems. They'll want an
arm and leg to check any of this so I'll keep avoiding it.

Thanks,
Brett

 

its really not too difficult, if you have a set of 1/2" sockets (or at
least one to turn the crank pulley) and a few metric wrenches to get the
valve cover off and do the job. oh- and a feeler gauge and spark plug
wrench i think a flathead screwdriver is also used on the valve adjust
bolt.