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Oil temp sensor

Removed copper oil temp sensor to clean oil screen, now temp inoperative. Removed again and ran heat gun over sensor with no movement on gauge. Used all care, assume I broke it!
Solutions/suggestions please.

Model: Bonanza B35
Aircraft Serial Number: 2561
Posted 10/7/2023 - 4 months ago
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Is it an electric sender, or does it use what is called a capillary tube to the gauge? The changeover was after the B35, but you can find both types in early Bonanzas. If you damage the capillary tube, the heat transfer medium will leak out and render the sensor DOA. If its an electric sensor, it will require 12V for the gauge to work. If you confirm your aircraft model and serial number, I will see if I can post the system schematic.

Posted 10/7/2023 - 4 months ago
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1950 Model B35 SN2561. Original mechanical with wire wound copper tube to gauge, opposing end is “capillary” copper cylinder about the size & shape of little finger. I was very careful removing the 2” long capillary and didn’t witness any damage, but here I am.

Posted 10/8/2023 - 4 months ago
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Steve, attached is a .pdf from the parts manual showing what you have. The first one of these I broke was was over 40 years ago working on an old MG sports car. Without knowing what you are working on, most folks just start unscrewing it and twist and crack the capillary tube. You can try Air Capital Dial or Fresno Air Parts for a replacement, but old gauges are getting extremely difficult to repair or source. Mike Thompson has some good ideas for an engine monitor which might replace the entire engine gauge cluster on early Bonanzas. Maybe he can offer some suggestions. I was seriously considering this a couple of years ago when I did the avionics upgrade on my G35. Fewer and fewer shops can work on analog gauges. A big advantage to this would be getting pressurized fuel and oil out from behind the panel.

attachment

B35 OT Sender.PDF - 326.7 KB

Posted 10/8/2023 - 4 months ago
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A follow up post in case Mr Jeub is still following this thread. I checked around and could not find a capillary oil temp sensor by Beech P/N at any of the usual vintage parts suppliers. All of the early Bonanza cluster engine gauges were either Rochester, AC or Delco automotive gauges. Look at your gauge and sender and see if you can pull a manufacturer and P/N off of it. There is a healthy market for vintage automobile restorations and you may be able to source it that way. Call me through the ABS office if you want to talk about the fix in more detail. I had an FSDO inspector claim such a part is “unapproved”. My reply was these parts were never individually CAA approved, but were approved as part of the aircraft. There was some head scratching, but all parties agreed to this. Be careful working behind the panel. There are all sorts of important wires, hoses, tubes and flight controls. This would be an A&P level project.

Posted 10/11/2023 - 4 months ago
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Absolutely Appreciate above assistance. Both were helpful.
Took a week away from the frustration in Las V!
Looking for a rebuild, if no-go will consider making the old gauge “inop” and do a separate oil temp gauge.

Posted 10/16/2023 - 4 months ago
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Decision time…would prefer restoring OEM but too many negatives. Largest factors were: downtime, probability of recurring issue, tech advances, ability to retain original gauges and look (but inop).
If going OEM West Valley Instrument in Reseda, CA can restore aprox. $300 vs new tech at $600. Specialize in old auto, I told them I had a Continental, (they were thinking Lincoln). Most of these resources are out of the biz.

For DIY see: www.ply33.com/Repair/tempgauge

Posted 10/19/2023 - 4 months ago
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Oil temp sensor