My son bought a 2000 Lincoln. It has the familiar problem (I'm told)
of oil leaks around the ignition coils and then subsequent failure of
some of those coils. He plans to replace all the oil seals associated
with this but first we cleaned all the coils and I checked them on the
bench with an ohm meter and they all look the same. I realize of
course that this is not conclusive though. These read like a standard
three terminal autotransformer type of device, so can I assume that
they function basically like a standard ignition coil? Can I apply 12V
across the primary momentarily to induce the secondary field? I have a
motor driven inturrupter of sorts that would accomplish this. I read
about a procedure on line apparently utilizing special Ford test
equipment, (WDC COP) and it shows oscilloscope waveforms associated
with the coils firing during test. It doesn't show a procedure or
connection diagrams though. I contacted the manufacturer of the test
equipment, Teradyne, but all they would tell me is that it is Ford
test equipment and that the equipment as well as the procedures are
proprietory. I would like to perform a similar test using my own
scope. Has anyone done anything like this? I would imagine that you
could use an inductive pickup similar to the type found on a timing
light placed around the secondary lead. I could wind a coil if need
be. Does anyone know if this would be a viable procedure, and if so
the details of the coil? Thanks, Lenny
It is more than just not conclusive, it will miss the most common problems,
which is a shorted turn. The thing gets hot, the insulation is damaged,
two adjacent windings short.
When this happens, it's like having an additional secondary winding that
is shorted added to the transformer, and it makes it totally inoperative
without changing the resistance of any winding appreciably.
What DOES change is the inductance of both windings, and if you can get your
hands on an RLC bridge you can measure that.
Otherwise you could probably test it on the bench with a spark gap and an
interruptor just like you'd test an old-style ignition coil. And yes, if
you want to see waveforms you could use a resistive load and a magnetic
pickup to see a waveform on a scope... but really the bridge will give you
a fast enough go/no go indication.
For that matter, you could just use a timing light with a pickup... clip
it on each one of them and you should see the light flash if there is good
HV... and the light won't flash or will flash intermittently if the coil
"C'est un Nagra. C'est suisse, et tres, tres precis."
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