[Peter Serio]

After 50 + years those old style GM gauges in the #4 pod (65,66,67) all have a 95 to 98% failure rate. Adding to the problem many of the modern aftermarket replacement senders that are commonly available are not made correctly for that old of a gauge.




I have fixed many GM (GTO) and Lemans temperature gauges over the past 30 years.

After I repair the dash gauge I choose an older (made in the USA) sender. You need and original GM sender, that or a car parts store brand sender that was made prior to the year 1990 or 1991 at the very latest. That was the last time those were made in the USA.

I test the sender and the gauge together, that is how I calibrate. Now GM wants money for the old blueprints, and you have to pay them in advance. Senders made overseas today have not been made according to the original blueprint because they do not want to pay for that. Odds are they have no running & driving 1966 or 1967 car over there to test them on nor would they even have the shop manual to your car.

I think they just guess. The other issue is they somehow envision about 20 to 25 years worth of senders (for 1960s and 1970s GM cars) with gauges are all the same, (because for a V8 application they all have the same thread pattern),= (1/2" X 14). I reality there are actually many different variations of temperature senders for older GM cars with factory option gauges! Today they just combine all of those older GM #s into one or maybe 2 aftermarket part #s; that is big part of the problem.