The story so far:
I found the nipple for one of the transmission oil cooler lines sheared
off at the radiator tank. I'd hit a wicked, unmarked narrow and tall
speed bump a few weeks earlier. The day of the blowout was the hottest
of the year, so far. (Note: stay clear of all side streets in San Pablo,
California). The 2000 Sonata is an unusually low-clearance car. My car
leaped into the air, then slammed down onto the bump.
I'm not able to work on the car here. My friend brought over his trusty
backyard muscle car mechanic (a former dealership man like HT). The fix:
we put on a nice transmission oil cooler, bypassing the radiator for
this. There's a lot of room for the cooler between the front plastic
grille and the radiator.
Here's the interesting part: everything's fine, except that the
temperature gauge is reading higher than it ever has before under all
conditions. I'm carefully testing the cooling system's prowess, putting
the car under a little more load every day. We're having a heat wave
here, so I gave the car its biggest city street loading so far: driving
home uphill with the AC on. Although the temp gauge reading is higher
than it's been for the last 7 years or so, it cycled over a small range
and kept within that range and recovering nicely. The computer reveals
that there are no stored codes and all the drive cycles have completed.
I've been a good mechanic, but mostly on stereo equipment, and tend to
look for correlations. Here's an interesting one. I keep a little
digital volt meter plugged into the cigarette lighter. This is showing
unusually high system voltage, which has been ranging between around 14
and, today, briefly 15.5.
My theory: if the system voltage is high, the reading on the temp gauge
is increased because the gauge, itself, is getting more juice. Is this
correct? Any comments?