Taking The Alfatross' Temperature (Post # 154)

Three senders for both oil and coolant temperature.

Veglia oil and water temperature gauges read degrees C.

I got a haircut today for the first time in two months. The barber insisted on taking my temperature with a forehead thermometer before I could come in. Temperature is an important indicator of whether things are running properly or about to crash and burn. The Alfatross has been keeping her temperatures to herself, but that's about to change. 

Suspecting that The Alfatross' olio and acua temperature gauges were not displaying accurate information, I set about trying to figure out if the problems were due to the gauges or the senders. The only way to do that conclusively is to remove the beautiful Veglia gauges from the dash and their senders from the oil sump and the radiator hose line and bench test them. In addition to the original senders that were on the engine when I got it, I acquired two others somewhere along the way, so I included all of them in the bench tests.

The laboratory thermometer in the bath  reads 87 C but the gauge reads 100 C!

Although the senders for the olio and acua temperature gauges are calibrated the same, and could be interchangeable, they look very different. The olio sender has a long "nose" compared to the acua sender. I don't know if there is a functional reason for this. Probably not. The testing station allowed me to check the compatibility and accuracy of various gauge and sender combinations by immersing the senders in a water bath set to different temperatures. I quickly learned that here at 7,000 ft elevation water boils at 92.7 degrees C (198.9 F) so I could not test temperatures at the top of the range--which is the most critical part! Later, I learned from Joey at MoMa that if I had used commercial coolant (antifreeze) instead of just water, I could have created much higher temperatures in the test bath. I tested needle movement on the gauges and changes in resistance readings with changes in bath temperature. It was immediately apparent that at least one of the senders was inoperative and the acua gauge always seemed to read too high. All that it really told me was that I needed to take the gauges and senders to MoMa Manufacturing in Albuquerque for a "second opinion".  It took Joey at Mo-Ma only a few minutes to diagnose my problems: the acua gauge needed adjustment and the two long-nose senders were defective.  The good news is that the two short-nose senders were OK and could be put back into service.