I have a 71 with the old style gauge with the larger red band for the HOT Zone. this gauge among others was recently restored and calibrated for a 200 degree temperature sender from the Taco Plate location.

Debacle: Once installed, the gauge does little or nothing until fully warmed up. Then, at that point the needle is barely past the ice-cold tick mark on the gauge face / maybe a 1/16" beyond its starting point. I am on my second brand new sender to eliminate that as the cause. The test for the gauge is to ground the sender lug to the body, turn the key and watch the needle hammer the far right side of the red zone.... which it does.

Does anyone know if the gauge of the wire matters from sender to back-of-gauge?

or any other illusive issues I am missing?

My lovely wife loves the 914 and would rather drive it than our 993 so this must be fixed.....

Thanks to all.

Sounds like the wrong sending unit. The 914 gauge use a sender marked 150C.

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at the least - search this forum >oil+temp+gauge< in the search box - then go to the LAST PAGE (331 circa 2003) and work your way back from there - lots of threads for you to consider

AND check this recent link oil temp gauge info
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from an old article in Porsche Panorama

(note - figure notations below refer to pictures in the original Pano article = I posted those comparative gauge/sender pictures a very long time ago - don't have a link at hand)

Alan Caldwell wrote:

"The four-cylinder, two-liter cars without console used two different combination instruments with oil temperature gauges. The original gauge of this type (914.641.101.30) was used until the end of the 1973 model year and pictures of it show a wide red zone similar to the 1973 console gauge. In 1974 and later cars, an updated gauge, 914.641.101.50, was used with a smaller red zone. I was able to borrow one of the 1974 and later gauges and found, like the 914/6 and 911 gauges, it had factory calibration marks on the edge of the gauge face indicating that the bottom of the white scale was 30°C (86°F), the beginning of the red zone was 156.7°C (314°F), and the middle of the red zone was 170°C (338°F).

Figure 3 shows the 914/2.0 combination instrument and the oil temperature calibration using a 200°C sender and the same method as for the console gauges. The results were very close to the factory calibration marks: the calibration thermometer indicated 308 °F at the beginning of the red zone instead of 314, which seemed within the accuracy of the method and gave some confidence that the rest of the numbers weren't too far off. The overall calibration of the combination instrument was also reasonably close to that of the console instrument with the smaller red zone. In the gauges checked with the stock 200°C sender, the red zone starts at approximately 300°F.

A nice advantage of the dash-mounted combination instruments with their removable oil temperature gauges is that small white transfer numerous can easily be added to the face of the gauge so you don't have to remember the calibration. In addition to the Porsche gauges, VDO offers an aftermarket oil temperature gauge with numbers on it (the range is from 120°F to 300 °F) and the sender specified for it is the 150 ° C unit. The gauge is somewhat smaller in diameter than the stock console unit (approximately two inches compared to 2 3/8), but an adapter is available which allows it to fit.

The USA 914 factory installed oil temperature gauges never included any numbers on them and the owner's manual advises that the needle will normally vary up and down within the white zone depending upon ambient temperature and engine load, but the owner is not required to take any special action unless the needle goes into the red zone.

Most Porsche owners don't trust gauges without numbers and the 914/4 situation was made worse by the first console oil temperature gauges (914.641.118.20) in the 1973 models showing very little needle movement regardless of conditions. The white zone on these early gauges was about an inch wide and the red zone about three-fourths of an inch. The sender unit with these gauges had a temperature value of 200°C (392°F) stamped on the headend. the normal operating range of 160 F to 210°F occurred over a small portion of the white z6ne (Figure 1)

In 1974, a new gauge (914.641.118.30) was introduced which had a much larger white zone and much greater needle travel than the earlier design. The sender unit that came with the newer gauge remained the same (part no. 039.919.268)

The first step in oil temperature peace-of-mind is to find out just how high your oil temperature really is.
The quickest and least expensive way to find where you are is to determine at least one pertinent calibration point on your existing gauge equivalent to 212°F.

The most convenient time to do this is during an oil change when all the oil is out of the engine. This can be done by removing the gauge from the car and also removing the sending unit at the left forward side at the bottom of the crankcase. (Keep track of the way the wires are connected to it).

Connect a positive (+) wire from the battery to the gauge (+) terminal and then run a connecting wire from the gauge to the center electrode on the sender. A ground wire from the sender base to the gauge ground (-) and also to the battery ground completes the circuit. The sender can then be immersed in boiling water and the needle on the gauge should stabilize at the point on the scale equivalent to 212°F.

This procedure is only approximate since increases and variations in line voltage with the engine running may cause slightly higher needle positions. However, the results should be close enough to tell you if you have a problem.
Even the single 212°F point obtained with boiling water is a significant position to know on your temperature scale, since it is toward the upper end of the normal operation zone of 160°F to 220°F.
If you want to get really scientific and have an oven or candy thermometer, you may be able to also check a wider range of temperatures up to the red zone by using cooking oil instead of water."


more references =

- Upfixin' Vol 4, p259

calibration

914 VDO

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I have the original Pano article in my files - just not quickly at hand

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