Oil Temperature Guage

[ew1usnr]

I wondered how one would go about adding an oil temperature gauge to a Falcon and found the following temperature sensor that is built into the oil drain plug.

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Classic Instrument Temperature Oil-Plug Sender - Part No: SN21. 0°F - 280°F, 1/2”-20 to fit GM and Ford oil pans. $33.15.
See: http://www.egauges.com/vdo_indS.asp?Sender=Classic_Temp&PN=SN21 (http://www.egauges.com/vdo_indS.asp?Sender=Classic_Temp&PN=SN21)
Temperature Gauge - Part No: VS26BBLF (http://www.egauges.com/vdo_ind.asp?Type=Elec_Engine_Temp&Series=Velocity_BBLF&PN=VS26BBLF). 140°-280°F, 2 1/16” black face with white numbering and an orange needle.Traditional Lighting (Reflective, not through dial). Classic Instruments SN22-SN25 temperature sender recommended. $54.50.
See: http://www.egauges.com/vdo_ind.asp?Type=Elec_Engine_Temp&Series=Velocity_BBLF&PN=VS26BBLF (http://www.egauges.com/vdo_ind.asp?Type=Elec_Engine_Temp&Series=Velocity_BBLF&PN=VS26BBLF)

The gauge measures from 140 to 280 F and 180°-220° F is said to be a good range for engine oil. The temperature sending unit will not extend below the engine and decrease ground clearance because (on a 260 at least), the drain plug is mounted on the side of the oil pan and not on the bottom.

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[Luva65wagon]

Begs the question of what to do about it if the engine temp reads good but the oil temp reads too high? Do you trust one over the other? Worry about one over the other? Is this something you are worried about in general on a street motor?

I would think if water temp was OK, then engine oil temp would not be any higher than that since a system tends to normalize at some point. My guess is you'd maybe have more an issue of oil temp differential on turbo motors, since the oil also acts as a coolant for the turbo. In cases like this you'd use an engine oil cooler too to assist in overall engine cooling.

Interesting temp-sender though. I've struggled myself with adding a new "mechanical" water temp sender on these 6 cylinder motors. They have 1/4 NPT on early heads and went to 1/8" NPT on post '63 heads. Most mechanical gauges use at least 3/8 NPT to accommodate the sending unit mounts. Guess you have to always use electrical style only. Too bad since I have 3 mechanical style units collecting dust.

Maybe I could drill and tap the head. :rain:

[ew1usnr]

The oil temp gauge would serve as a back up to the water temp gauge. There would be a problem if they read differently. If your water temperature gauge fell and your oil temperature gauge went up, that might indicate that you have burst a radiator hose and lost coolant, for example. If the water temp gauge stayed on cold while the oil temp gauge read normal, you might have a loose electrical connection or a sticking water temp gauge.

I verified the accuracy of my original water temperature gauge with a "ThermoCap". They both read the same.

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See: http://www.jegs.com/i/Mr-Gasket/720/2470R/10002/-1?parentProductId=874786

[pbrown]

The oil temp gauge isn't that useful on a non-turbo street motor.

Oil temp is higher than coolant. The last oil temp gauge I played with was on a friends WRX motor. It read about 220F when fully warmed up. It was also interesting to see that the oil took a lot longer to get to full temp as compared to the coolant.