[Mgs] the voltage stabilizer dilemma

Councill, David dcouncill at msubillings.edu
Wed Nov 21 13:42:14 MST 2012


Another warm day today so I drove the 72B to work today. It does have an
interesting problem of which I need to provide a bit of history. I had a body
shop restore and paint a 72 body shell (a parts car I bought about 10 years
ago), and I transplanted the drivetrain (engine, transmission, rear axle) from
my rusted out 71BGT in to it. After I got it running, I noticed that the
engine appeared to overheat (on the gauge) which turned out to be an
improperly grounded voltage regulator. I fixed that problem but the fuel gauge
always tended to read low. In particular, a full tank always starts about 1/8"
below full and drops to > after 10-20 miles and then = tank after about 80
miles. I know I can recalibrate the gauge but it was just an annoyance so I
put it off. The coolant temperature gauge also probably ran low as it always
ran a little below the halfway mark, below "N" but nothing unusual there.

Then a few months ago, I noticed that the coolant temperature was running a
bit cooler, about halfway between C and N, so I bought a thermostat which I
still haven't got around to replacing. Maybe that was a good thing because the
last month or so when driving, I noticed that sometimes the coolant gauge
would actually drop to almost "C" and the fuel gauge would like wise drop,
only to return back to more normal readings minutes later. With both in
tandem, I figured it had to be the voltage stabilizer. And at a cost of around
$11, I bought a new one from Moss and installed it.

Yesterday, with an almost full tank of gas (6 miles less than full and the
gauge at its usual full position about an 1/8" shy of F), the problem
reappeared. I was driving, glanced at the coolant temperature and it was down
to almost "C" and the full tank read a mere half tank on the fuel gauge. A
mile or so later, it was back to normal. So it doesn't look like the
stabilizer unless I coincidentally have two bad ones (not likely but not
impossible). Things are normal this morning but this evening will be a drive
in the dark if that is relevant. I should throw in the fact that during the
restoration (~8-10 years ago), I replaced the wiring harness with a new one
and the instrument gauges are grounded with the black ground wire from the
harness.

So I am not sure the next step to figure out this annoyance. But I figure
since the list isn't seeing much traffic right now, this will make a timely
inquiry and save us from someone posting on whether the list is up or not :)

David Councill
64 B
67 BGT
72 B


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