Oil Temp guage replacement

[Gary]

My original Cessna oil temp gauge part #0411017-3 failed on the return from Oshkosh this year. It failed, I know now, because we keep moving the capillary tube back and forth while replacing the failed Vacuum pump at the show. It did a slow death on the way home with the temps slowly dropping on the first leg back to VA. I have an EDM 700 with oil temp, so I knew the temps were good coming home. I searched the forums here and found a link to a repair shop at Lock Haven, PA. They want a whopping $280 and 4 weeks to repair! I found lots of links here about Scott and Rochester gauges installed on 170s. I bought a Rochester from Spruce for $76. I have read about the adapter and oil leaks.... it came with a new adapter. My question is how do I legally replace the Cessna part with the Rochester part? Looks like I need to add a new red line to the gauge as it goes from 100 to 250. I have the Lycoming 180 HP. Thanks, Gary

[GAHorn]

First you remove the old gauge...then you install the new Rochester gauge after you've properly marked it. Then you log the activity into the records.

It's a minor alteration and besides that, AC 23-27 allows the use of that gauge in aircraft built prior to 1971.
(It may be reassuring to note that Rochester built the original rectangular gauge for Cessna, as well as the Scott gauges for them.)

[Gary]

Thank you George. I thought it could be done, but best to check with the experts here at the 170 site. As always, thanks for the great info. Gary