View single post by Mark Rosenbaum
 Posted: 06-28-2005 12:21 am
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Mark Rosenbaum

Joined: 03-12-2005
Location: Kingman, Arizona USA
Posts: 532
Before changing the thermostat, I'd check two things:

1.  Correctly operating temp gauge.  With a coolant temp at a measured 80^ to 85^C (the normal operating temperature for the stock 82^C thermostat), the gauge should read mid-range or a needle's width to the right.  However, as Judson notes, the actual reading depends greatly on the voltage stabilizer.
     (a)  If the stabilizer fails in the 'always off' mode the temp gauge and fuel gauge will not work.
     (b)  If the stabilizer fails in the 'always on' mode the temp gauge will appear to operate normally at first, but will rise to, or into, the red zone as soon as the engine reaches operating temperature; simultaneously, the fuel gauge will indicate far more fuel than is actually present (which is hard to detect if the tank is full).  This seems to correlate with your car's symptoms.

2.  Presence of coolant in the heater core -- air can be trapped there and later transfer to the engine, causing localized internal overheating.  Your car is late enough that it may have a vacuum operated valve in the hose to the heater, and these are notoriously unreliable.

Of course, as Greg notes, a thermostat can fail at any time and without warning.  Worse yet, they sometimes fail intermittently and seriously confuse the issue.

Last edited on 06-28-2005 12:22 am by Mark Rosenbaum