Well, it has been a long troubleshooting event. Leading down multiple rabbit holes.
I removed the engine from the plane to access the firewall for the governor cut out and also to send it in to an engine shop (name held on purpose). As the engine was already at the shop I asked the shop to convert it to constant speed. They said no problem.
Everything should be working, they are professionals.
After I did the test with the air on the 90 degree fitting (nose of the engine that gets the governor line), I started researching on VAF and other sites. That lead me down the path of the hole or no hole, NPT plug or not.
in order to confirm the problem, I tried to prove that saying of "insanity is doing the same thing over and over again, but expecting different results".
in this case, I was not insane. The results would differ and were not predictable. Sometimes I would put 40 psi of air in the plug and the prop would move. Sometimes i would cycle the prop a few times with the engine running and it would work. Then it would not work after a certain number of prop cycles. Sometimes it would work if I "double pump" the prop lever is my RMP was at 2200. Seemed like it always failed to cycle at around 170 deg of oil temp. All that took time to diagnose and collect.
I designed a pressure differential tool that would work just like a cylinder compression tool. I would put 40 psi of air in the 90 deg fitting and read the actual pressure in the system. Sometimes the tool would real 22-24 psi and the blades would move; and some times the 40 psi was going straight out of the crank case vent without any prop movement or pressure.
Talked to a local A&P and he said I should instrument the governor to check the pressure. So I contacted the PCU5000 folks for guidance on how much pressure I should see at what governor rpm. They told me that max pressure of 320 psi plus/minus 20 happens as low as 1700 governor rpms. So 1700 times the governor ration of .866 gave me the engine rpm required. at 1600 ish engine rpm i should have a good check of governor pressure and not blow the gauge to the moon. I ran the engine at 1600 rpm and the pressure gauge read 350 psi. I called that good as the calibration on the gauge was not checked for accuracy prior to using. we just knew it work as they A&P uses it to check pressure in the fuel/oil lines he makes. Pics below of the set up.
I then designed a governor pad test plate on Solid Works using the Lycoming Service Instruction 1462. Once that was done, I used my 3D printer and made the plate. Aircraft Spruce wanted over $2000 for that part. It cost me about $4 in plastic and 45 minutes of computer time. Following the service instruction I was still getting inconsistent readings for pressure. Same as with the pressure differential tool i made for the 90 deg fitting. Pics below. Forgot to take a pic of the actual part.
The next logical step was the crankshaft plug. Even though i visually looked at it before I put the prop on. So I ran the engine and sure enough, prop worked fine for approx 20 minutes of cycling. I ran it until it stop cycling, then shut it down. interestingly enough, oil temp was 174 deg (i use Aeroshell 100 Plus).
Next step was to pull the prop. One buddy kept telling me that I left a plastic plug in. That was not it. But I kept thinking that some of the problems ("double pump" on the prop lever, oil temp at 170 deg) were pointing at partial blockage or poor seal of oil in the crankshaft or crank case. I found a gentleman (thread on VAF) that said his crank case broke a piece inside that was improperly manufactured. I was hoping that was not the case. Prop came out and i found this.
WTF?! is that plug crooked? Is that rust? When I first looked at the plug I remember thinking, "why would the shop not clean the inside of the crankshaft?".
So I grabbed a wooden dowel, put it on the plug, and tapped gently. The plug came right out. Double WTF.
I pulled the prop extension so I could get the plug out and this is what I found. A USED AND RUSTED PLUG INSTALLED.
Continue on next post due to posting limitation.