Need 0-300D oil pressure orific

[Plummit]

Hi All, does anyone have a part number for the oil pressure fitting that screws into the engine? I need one that is a dash-3.

TIA
-Marc

[Bruce Fenstermacher]

It is a AN816-2B according to the Cessna IPC. B means copper alloy (brass) and in this case soldered closed and a #60 hole drilled in it. You could also buy a steel (no alloy mark) version and solder or braze it closed and drill it. I've also taken an aluminum (D alloy mark) version and tapped it on the outside and inserted an appropriately threaded plug and drilled that. Need a -3? You'll have to adapt the -2 up to -3 size but not sure how you'd do that nicely.

[Plummit]

It is a AN816-2B according to the Cessna IPC. B means copper alloy (brass) and in this case soldered closed and a #60 hole drilled in it. You could also buy a steel (no alloy mark) version and solder or braze it closed and drill it. I've also taken an aluminum (D alloy mark) version and tapped it on the outside and inserted an appropriately threaded plug and drilled that. Need a -3? You'll have to adapt the -2 up to -3 size.

Thanks Bruce. I have the -2 fitting but for some reason my C-172 was using a -3 fitting and hose that went through the firewall. I'mlooking for an easy way replace the -2 and it may be that I have to modify a -3 fitting. I suppose I could have a special hose made up that would have different ends on it.

-Marc

[Bruce Fenstermacher]

Well on closer inspection it looks like the AN816-3 still has a 1/8" straight NPT thread, same as the -2. So it will fit into the engine. So you could by a AN816-3 (Steel, B, or D) and modify it for a #60 hole as I described for a -2 above, then connect your -3 hose directly.

[n2582d]

… my C-172 was using a -3 fitting and hose that went through the firewall. …-Marc

Marc,
Not sure if I’m interpreting what you wrote correctly, but the oil pressure hose should have an AN 832 bulkhead union fitting at the firewall.

I assume you have an O-300 powered 172, but in the event you have a 172I or 172K, be aware it is the subject of AD 70-10-06 which calls for replacing the copper oil pressure line with a hose.

[Plummit]

We are swapping one 0300 D for another (fresher) 0300 D that came from a C170 doing the Stoots STC. Our 1960 C172A had a -3 hose for the oil pressure connection from the engine to the firewall. There's no transducer as we are using legacy gauges. The new(er) engine had a -2 orifice mounted. Normally I would just switch out the fittings but removing the -3 from our old engine will be problematic as it is a 45* fitting and getting it out without damaging the threads will be no picnic.

I ended up ordering a new hose from Aircraft Specialty with a -3 on one end and a -2 on the other. Looks like that will take care of the mismatch.

-Marc