Wet oil pressure switch?

Yesterday we put new coolant into my 1.9. Using a "Libby Bong" one can
get quite a gusher out of the bleeder in the engine compartment. Coolant
washed over the oil pressure gauge sender and oil pressure switch which
are moved above the left head when using tencentlife's adapter setup,
which I am.

Drove the van briefly yesterday, and there were no warning lamps,
everything read okay. But this morning, I needed to move the van a
couple hundred feet and the oil pressure lamp did not go out even though
the oil pressure gauge read normally. But the lamp was not on at full
power, either: it was only at half-brightness.

I had to run a bunch of errands in Mrs Squirrel's car in the morning,
but after lunch I brought the van back to the driveway, and the oil lamp
was quite dim, but not out. Turned off the engine, connected a voltmeter
to the switch's "hot" terminal and turned on the ignition w/o starting
the engine. Read about 0.5V. Started the engine. Read 10.5 volts.
Puzzled I check the dash lamp -- dark. Revved the engine to kick in the
alternator and the voltage rose to about 11.5 or 12V and the lamp, of
course, was dead dark.

Took it for a long drive, no sign of spurious lamp lightage.

It's my theory that the oil pressure switch was soaked with coolant and
offered a sufficiently low enough resistance to allow current to flow
through the lamp to cause it to partially light. Then it dried out.

Even though a brief check with an ohmmeter showed that a 50/50 mix of
G-05 coolant is about as conductive as distilled water, this is my story
and I'm sticking to it.

--
Jack "Rocket j Squirrel" Elliott
Bend, Ore.
1984 Westfalia. A poor but proud people.
1971 "Ladybug"-brand utility trailer ca. 1972 from a defunct company in
San Clemente, Calif., now repurposed as The Westrailia.