Return-Path: Received: from wb1-a.mail.utexas.edu ([128.83.126.134] verified) by logan.com (CommuniGate Pro SMTP 4.2b8) with ESMTP-TLS id 327769 for flyrotary@lancaironline.net; Tue, 20 Jul 2004 11:37:06 -0400 Received-SPF: error receiver=logan.com; client-ip=128.83.126.134; envelope-from=msteitle@mail.utexas.edu Received: (qmail 67704 invoked from network); 20 Jul 2004 15:36:37 -0000 Received: from dhcp-191-101.per.utexas.edu (HELO benefits3.mail.utexas.edu) (146.6.191.101) by wb1.mail.utexas.edu with RC4-SHA encrypted SMTP; 20 Jul 2004 15:36:37 -0000 Message-Id: <5.1.1.5.2.20040720102340.029c0968@localhost> X-Sender: msteitle@mail.utexas.edu@localhost X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Date: Tue, 20 Jul 2004 10:36:30 -0500 To: "Rotary motors in aircraft" From: Mark Steitle Subject: Re: [FlyRotary] Re: High Temperature Readings In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=====================_65346343==.ALT" --=====================_65346343==.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed Rusty, Yes, it sounded rather strange to me too, but gauges are their business. It seems at the very least that it might be worth checking the resistance between the sensor body to a/c instrument buss ground (not just the engine) to be sure that a poor electrical connection isn't causing higher temp readings. While they didn't mention it, I was curious if there is a "conductive" sealant that might be better choice to use with sensors? BMA recommends the use of ungrounded sensors to avoid ground loops. They recommend running the ground all the way back to the DB connector. Could be something to it after all. Mark S. At 09:19 AM 7/20/2004 -0500, you wrote: >Should I use sealant or Teflon tape on the threads of my sender? Do not >use sealant (including Teflon tape or plumbers pipe dope) on the threads >of temperature or pressure senders. This will not allow the sender to >properly ground itself to the engine and will cause the temperature to >register high and the pressure to register low. This does not include >floating ground senders which include a second terminal specifically for >grounding. > >I just don't buy this. Most sensors are pipe thread, which are made to >get tighter as you screw them in. No Teflon tape, or sealer in the world >is going to keep that sensor from making metal to metal contact. "Maybe" >it could be a problem with a straight thread sensor, using an O-ring >seal. I still doubt it though. If in doubt, put an ohmmeter between the >sensor body and the housing that it's screwed into. > >Cheers, >Rusty (sealer on everything) > --=====================_65346343==.ALT Content-Type: text/html; charset="us-ascii" Rusty,
Yes, it sounded rather strange to me too, but gauges are their business. It seems at the very least that it might be worth checking the resistance between the sensor body to a/c instrument buss ground (not just the engine) to be sure that a poor electrical connection isn't causing higher temp readings. While they didn't mention it, I was curious if there is a "conductive" sealant that might be better choice to use with sensors? BMA recommends the use of ungrounded sensors to avoid ground loops. They recommend running the ground all the way back to the DB connector. Could be something to it after all.

Mark S.

At 09:19 AM 7/20/2004 -0500, you wrote:

Should I use sealant or Teflon tape on the threads of my sender? Do not use sealant (including Teflon tape or plumbers pipe dope) on the threads of temperature or pressure senders. This will not allow the sender to properly ground itself to the engine and will cause the temperature to register high and the pressure to register low. This does not include floating ground senders which include a second terminal specifically for grounding.

I just don't buy this. Most sensors are pipe thread, which are made to get tighter as you screw them in. No Teflon tape, or sealer in the world is going to keep that sensor from making metal to metal contact. "Maybe" it could be a problem with a straight thread sensor, using an O-ring seal. I still doubt it though. If in doubt, put an ohmmeter between the sensor body and the housing that it's screwed into.

Cheers,
Rusty (sealer on everything)

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