From:Kevin Flanagan
Subject:More on oil gauges Date:Mon Nov 30 07:48:31 2009
While reading through some back articles, I came across one on servicing the Henderson oil gauge. It mentioned the needle not returning to zero upon rest, or an inaccurate reading when compared to a modern gauge. My two cents worth-when your gauge becomes inaccurate, pulsates when operating, or does not return to zero, it is usually caused by the dogbone bushings and pins being worn from normal usage. When this happens, the hair spring inside the gauge has a tendency to push the needle ahead (off zero), to compensate for the normal wear. The only problem with this is your gauge does not return to zero. Sometimes when running, vibration will cause the needle to flutter, bouncing back and forth in the worn bushings, if the hair spring is not wound tight enough to keep the bushings pushed against the worn pins. It sounds like a simple fix, but I would not recommend attempting to adjust the bourdon tube as it can affect the accuracy and possibly kink the tube, I would not recommend using air to test the gauge as even at a lower pressure it is possible to get a surge of air which could "straighten out" the bourdon tube if not careful. An unsuspecting friend brought one to me with his straightened considerably, unfortunately unrepairable. Not to make a sales pitch, but I can replace the bushings and regrind the dogbone pins if anyone needs my services. I also can pressure test compared to a standard gauge for accuracy using a hydraulic gauge comparator. Happy Holidays- Kevin/Indian Gauge Company