So the 340A is fixed….
It wasn’t an oil pressure problem, it wasn’t a gauge problem either though. (I didn’t think it was an oil pressure issue, as there was no other indications, like increased oil temp or stuff like that, but one never knows). But now we know for sure:
It was a clogged line.
See, the oil pressure is not indicated through an electrical sending unit to an electrical gauge, but real oil pressure delivered to a real pressure gauge via a small diameter pipe. Old school.
It goes from a manifold of a few oil lines, across the engine bay, into the wing structure, to the fuselage, up through the pressure bulkhead into the pressure vessel, then towards the front of the fuselage, up behind the instrument panel, over to the right side, then into the pressure gauge.
When the A&P mechanic pulled the cowling, he found the connection where it went into the wing, and disconnected that. We then turned the engine over and no oil came out, even after we pulled the top spark plugs so that the engine could turn faster. Not the way it should be….
Following the line back we found where it goes into the manifold, and disconnected it there. Lots of oil when we turned the engine over. So the issue was isolated to somewhere in that 14 inches or so of oil line.
We attempted to blow it out with low pressure air.
No dice.
So that portion of the oil line got pulled and inspected. There was some discoloration at a bend where it passes in front of the exhaust side of the turbocharger.
A bit of solvent and some higher pressure air and the clog blew out. Lots of solid stuff. I expect that it has been building up like a clogged artery just before a heart attack, until finally there was no indication at all in the cockpit. There is normally no flow of oil, just pressure, so that bend where it was near the turbocharger just got hotter and hotter and more and more clogged.
Put it all back, and turned the engine over again and we had indicated oil pressure.
That was Tuesday. Wed it was fog, freezing fog and low IFR, not exactly the weather I wanted to take a plane with an unknown (maybe fixed, maybe not) engine into.
Thursday was, of course, Thanksgiving. Friday I fired it up and spent a long time doing some higher power runs on the ground before taxiing and then I took it up and everything was good, although at some point we are gonna have to bleed the air out of the line from thee engine bay to the gauge…I flew for about 45 minutes at different power settings varying RPM’s and airspeeds….All was good and normal. Did two practice approaches during the test flight.
But it is fixed without any issues. I did did make a heat shield for it, and will be making sure at the annual inspection that the other line on the other side has not got the same issue. I think that it was just turned a tiny bit when the engine was installed, leaving it just too close to the turbo (Which runs at or near 1550 degrees F in cruise).
Of course, now that that is done, it is time for the annual, as it is due after 11/30 (end of the 12th calendar month) But at least I know it isn’t a mechanical issue with the engine. And I didn’t shell out a fairly new TSIO520 Ram VII engine.