O-300 Overhaul for '98C

Roesbery · Post by **Roesbery** » Wed Jun 14, 2006 7:55 pm

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

cessna170bdriver · Post by **cessna170bdriver** » Fri Jun 16, 2006 7:51 pm

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cessna170bdriver · Post by **cessna170bdriver** » Mon Jun 19, 2006 5:57 am

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cessna170bdriver · Post by **cessna170bdriver** » Mon Jun 19, 2006 6:51 am

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Roesbery · Post by **Roesbery** » Tue Jun 20, 2006 1:53 am

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?

Post by **GAHorn** » Tue Jun 20, 2006 6:14 am

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.

Roesbery · Post by **Roesbery** » Wed Jun 21, 2006 7:19 pm

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.

Post by **GAHorn** » Wed Jun 21, 2006 7:54 pm

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.

cessna170bdriver · Post by **cessna170bdriver** » Wed Jun 21, 2006 10:55 pm

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N2255D · Post by **N2255D** » Wed Jun 21, 2006 11:43 pm

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

cessna170bdriver · Post by **cessna170bdriver** » Thu Jun 22, 2006 12:19 am

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Post by **GAHorn** » Thu Jun 22, 2006 2:17 am

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.

n4517c · Post by **n4517c** » Thu Jun 22, 2006 2:55 pm

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

cessna170bdriver · Post by **cessna170bdriver** » Sat Jul 01, 2006 6:14 am

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steve grewing · Post by **steve grewing** » Sat Jul 01, 2006 11:17 pm

Congratulations Miles. Photo tells it all.
Steve