1965 Corvette: Engineering Service Letter: Temperature Gauge Reading Too High
Subject: Temperature Gauge Reading Too High (No. 250-TSB-DR)
Model and Year: 1965 Corvette
Source: Chevrolet Engineering Service Letter
Bulletin No: TNP #66-1
Section: Section XII - Electrical and Instruments
Several field reports have been received describing owner complaints of excessive temperature gauge readings.
Investigation has revealed some faulty gauges, however, it appears that the complaints may be largely psychological in nature. This may be because at normal operating temperatures the needle is positioned vertically or to the right of center and under extreme conditions the needle may be positioned physically close to the "Hot" mark although coolant temperature is within safe limits.
In production for 1966, the temperature gauge has been recalibrated so that at any given temperature the needle will be positioned further to the left, hence farther from the "Hot" mark. Under normal operating conditions the needle will be positioned to the left of center and extreme conditions will give a needle position at the center or right center of the gauge.
The gauge when available, may be used in the field as a replacement for the present gauge to alleviate owner complaints of high or erroneous gauge readings. Under no condition should any type of resistor be used to recalibrate either the new or present gauge.
The gauge cannot be used as a replacement on 1963 and 1964 Corvettes because of a styling change to the gauge face.