oil temp guage

[CWizard]

John said: I just bought a 2001 SPF and the oil temp guage isn't working. What do you think the most likely cause would be?

John - Assuming it's the standard SPF gauge, it will be a Smiths mechanical gauge. Easy to tell: Does the face say "Smiths"? Is there a small tube enclosed in a somewhat larger wire spiral (which protects the small tube) running from the back of the instrument panel gauge to some point on the engine, or maybe to the remote oil filter block, at the front of the engine? If the answers are yes, you have a 1960's technology Smiths mechanical gauge. Assuming you do, the most likely cause for failure is a hole in the small tube that is enclosed by the wire spiral. That tube contains ether, which expands as temp increases, and causes a deflection of the needle (yes, it's really a pressure gauge calibrated to temperature). A small ding in the tube can allow the ether to leak out, and kill the gauge. There are no replaceable components on this gauge; you have to replace the entire thing. Mine has been replaced twice. If you replace yours, handle the new gauge carefully. Oh, and you might want to check the calibration of the new gauge before installing it. Put the bulb into a pot of water (suspended so that it doesn't touch the metal of the pot) and heat to boiling. Gauge should show close to 100 C when the water boils. If you have an accurate thermometer, you could also put it into the water (suspended as the bulb on the gauge) and check the gauge reading against the thermometer as the water heats and cools down.
Maybe better yet, replace the failed gauge with a new electric one. Autometer has some nice vintage looking electric gauges.
Good luck.