The International Cessna^® 170 Association

Put a magnet to that "copper" oil line and see what happens.

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Must be copper, may have been replaced at some point. Mine is copper plated steel, a lot stiffer, and stronger than copper. I would like to find a source of the 1/8" copper plated steel line. Any Ideas?

Roesbery, what you may be seing is cadmium plated line. I've seen that issued as fuel injector lines, but usually that also is tempered and has a silver-soldered bulb-fitting on the end. Tempered steel does not flare easily in small sizes without splitting.

Did a flare one time, didn't split, but was a trick getting the tip of the flare tool started, been a few years (quite a few) still holding. Would like to change the copper line to the fuel pressure gauge to steel with a rust free outside. I don't trust copper in a high vibration flexing inviroment.

That's the issue, of course. Copper will work harden and over time will also embrittle due to vibration. It's a poor item to use in pressure service. I'm frankly surprised that it hasn't had a mandatory service bulletin at the very least, and that's why I intend to replace mine when I can get a hose made.
Meanwhile...everyone might check their oil pressure fittings to see if they are ordinary AN fittings or if they are the correct restrictor fitting. The restrictor has a pin-hole in it to pressurize the oil sense line so that should the line break...you won't lose all you oil overboard in a flash....you'll just have a nasty oil leak to discover when next you land.

Here's a pic of one on a Lycoming:
http://www2.tech.purdue.edu/at/Courses/ ... itting.JPG

FWIW: The oil sense line should be filled with kerosene as a sense-oil. That way the gauge will be more responsive, especially in cold wx. Very lttle, if any, actual engine oil will enter the line. A larger capacity oil sense hose should alleviate that issue, as any pressurization of the hose should be less restrictive to congealed oil.

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FWIW: The oil sense line should be filled with kerosene as a sense-oil. That way the gauge will be more responsive, especially in cold wx. Very lttle, if any, actual engine oil will enter the line. A larger capacity oil sense hose should alleviate that issue, as any pressurization of the hose should be less restrictive to congealed oil.

Personally I use MMO in the line

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N2255D wrote:

FWIW: The oil sense line should be filled with kerosene as a sense-oil. That way the gauge will be more responsive, especially in cold wx. Very lttle, if any, actual engine oil will enter the line. A larger capacity oil sense hose should alleviate that issue, as any pressurization of the hose should be less restrictive to congealed oil.

Personally I use MMO in the line

I realize this was a jab .... ... but have you ever witnessed what's left when MMO gets old? It's worse than sticky-varnish.

I replaced my oil pressure line a couple of years ago with two 20 inch -3 Teflon/Stainless sections. The -2 fittings for the -3 line were available but not commonly stocked. Part number for the lines was P/N 12400IRRA-0200-C

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Congratulations Miles. Photo tells it all.
Steve