Quote:
Originally Posted by Peter Serio
When an older GM gauge "chatters" that is a sure sign that the buffering fluid inside of the gauge is gone.
FYI: GM put inside of all of it's gauges 2 or 3 drops of glycerin. The fluid actually serves 2 purposes: A) it acts as a lubrication for the moving parts inside of the gauge and B) it dampens the movement of the pointer so that the gauge reads smooth and steady. Over a time span of more than 50 years (summers & winters) the fluid eventually leaks out of the gauge. Once the fluid is absent the gauge bounces around with a herky-jerky motion, especially an oil pressure gauge. The final failure is that the pointer will detach from it's shaft and fall down into the cluster.
The fluid can not be expected to stay inside there forever.
I agree with all posts above that, in general service parts (in this case the sender) sold today for a 50 year old car are no longer made to the same quality standards as the original GM parts.
The cure in this case is to replace the dash gauge.
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Fluid in an electrical gauge? I've had my cluster completely apart including repairing a needle on my temp gauge. There is no fluid in my 69 GTO gauges and the jerky crap is caused by intermittent direct ground being supplied to the gauge causing the erratic movement.. The electrical gauge position is controlled by the amount of "ground" being supplied to the gauge through the sending unit which positions the gauge in the respective position based on electrical current. Agree, the erratic "pounding" of the gauge caused by intermittent direct ground could eventually cause damage and knock the needle off I would assume. Furthermore, this issue is solved when you replace the oil pressure sending unit, in my case I've seen it work for a year and the recent replacement failed after about a week. My assumption is the ACDelco part being produced is crap.
Anyone try the "Standard Motor" alternative sold by Summit?