Tick tock—is it
your clock?
by Walt Brewer
When checking
out your clock to see if it’s working, you want to hear a ticking sound.
When your engine is running, you
want to hear a hum and not a ticking noise.
For some reason, ticking scares old car owners more that grinding,
clunks or thumping, particularly in our old flathead V-8s.
As a rule, the first thing to get
the blame is the valve lifters. This is a good guess, but not always. In fact,
it may be less than a 50 percent chance. As many of you know, most of my
experience and forte is in the ’48 and earlier flathead LaSalles and Cadillacs,
however, many of the reasons for ticking apply to many of these old cars. Let’s
talk about a few of these reasons.
Everybody wants to blame the
hydraulic valve lifters first. The lifter assembly in the early flatheads
consists of the lifter body that rides on the cam and houses the two-piece
plunger assembly.
If the ticking is coming from the
lifter body, it is usually because of poor lubrication or a small crack in the
body itself. If it is in the plunger assembly, it is usually a small piece of
dirt or sludge in the check valve, possibly a broken spring in the plunger
assembly or some other small fracture. In any of these cases, this is not a job
for the Sunday mechanic.
More of a chance exists that the
ticking is coming from the valve assembly. This assembly consists of the valve
itself, the valve spring, the upper washer, the lower washer and two small
keepers. Each of these 16 assemblies fit into its own valve guide. Any fracture
in any one of these pieces can cause a ticking.
Also wear (either normal or
excessive) can cause the ticking sound.
You can also get the ticking sound due to inadequate oil flow or
pressure. This can be due to a defective or weak oil pump or blocked or leaking
oil passages.
In any of the above events, you have
major and somewhat expensive repairs needed. These repairs should be done by or
with assistance of a mechanic experienced in this field.
I have seen cases where large sums
of money have been spent on a “major” valve job and the valve train is still
noisy. The reason? Improper assembly, such as failing
to properly charge the lifter assembly, valve washers upside down, failing to
replace valve guides, et al. Usually it is because the
“mechanic” failed to grind the valve stems to the exact proper length. If you
grind too much, it leaves a gap and—that’s right—a ticking sound. If not
enough, the valves don’t wear well and you get low compression, detonation and
sometimes this sounds like “lifter noise.”
It is a shame to see a grown, old
car owner cry after spending big bucks for a full valve job (done right) and
still have a ticking sound. How can this be, you ask? It means that the ticking
sound is coming from somewhere else, as I told you earlier. You may have
wrongly accused the valve assembly. So, before you go into an extensive valve
job, let’s look at other reasons for “ticking” sounds. I will assume at this
time you can distinguish between a ticking and a knocking and don’t confuse the
two.
An inexpensive mechanic’s
stethoscope can usually at least find the general area of the ticking sound. In
most of the old flatheads, you have a double action fuel pump that will make a
ticking sound when operating. When rebuilding, the fuel pump will usually get
rid of this sound unless the arm that rides on the cam is worn to the point of
not keeping steady contact with the cam lobe. In that case, you can get another
arm or build the surface up by metal spray technique.
Of course, if it is the cam lobe
itself, it is a little more of a problem.
Fortunately, the cam lobe that operates the fuel pump can be separated
from the cam and can be rebuilt or replaced without removing the cam. Your stethoscope
can point this out for you.
The generator can also be a source
for ticking that sounds just like valves. Again, your stethoscope will pinpoint
this problem. Easy removal and a rebuild by a good generator shop can take care
of this.
Sometimes your fan blade can be bent
slightly and a tiny corner is hitting somewhere. A little bending can fix this
in a hurry. Both the fan and water pump have bearings that with a little dirt
or a flat spot can sound just like a bad valve lifter. Again, your trusty
stethoscope can find this for you.
Another common problem for a
“ticking” sound is a frayed fan belt. This is a little harder to locate.
Probably the most heartbreaking incident I can recall for a ticking sound was
from a car owner who came to me after spending thousands of dollars doing all
of the above, and still the engine sounded like the lifters were sticking and
clicking. Using the stethoscope, it sounded like the noise was everywhere.
After about an hour of reviewing all of his receipts and bills and correlating
the sequence of repairs, we determined that the noise started shortly after
installing new fan belts during routine maintenance prior to a tour.
We took off one of the fan belts to
help isolate the ticking. It was still there. We then took off the other belt
and the engine ran silent like a fine watch.
Close examination of that belt showed a half of a lock washer had broken
off a bolt and stuck itself in the belt, almost out of sight. Every time the
washer hit the pulley on the generator, water pump and crankshaft pulley it make
a tick (three times per revolution). The needlenose pliers pulled out the piece
of lock washer, the belt was replaced and guess what—it ran great and quiet. I
thought he should be happy, but all he wanted to do was bang his head against
the garage wall.
I guess it boils down to when you
wonder what makes your engine tick—check out the easy and cheap things first
before you blame the valve lifters.
See you next month—I gotta go check
out a ticking sound. I hope it’s just the old clock on the mantel.
—Walt