Colin wrote: ↑Wed Jul 19, 2023 12:53 pm
I had a leak from a through bolt. Some examination revealed that it was that the thread they wrap around the bolt to help seal it was wrapped in the wrong direction. (I don't know the technical name for that thread and was shocked that it could be wrapped in the wrong direction and that it would result in a slow leak.) Re-wrapping it would require cracking the case, something I was not willing to do. I think sixty hours after I sold it the engine needed an overhaul and I hope they did it then. It bothered me for the whole 1,400 hours I flew the plane.
The engine has 94 hours on it now and the leak is pretty noticeable and seemingly getting worse, so I definitely think we need to get this sorted. Fortunately it is still under warranty (two years 500 hours) so worst case I have it ferried back to the overhaul shop in Georgia. I really hope it's something simple, like the prop governor nuts backing off per Rich's suggestion. But the gasket was just replaced 16.2 hours ago and there is a good deal of oil so it seems there may be something else going on.
The overhaul shop asked to have SouthTec thoroughly clean the engine and ground run to determine the source of the leak.
SouthTec thinks it's the prop governor or starter flange leaking, so I will bring the plane back to the overhaul shop once SouthTec has addressed the other items. Fortunately the plane is in NC now so the hop to GA is pretty short, and James (at the overhaul shop) thinks he can things quick if it's just the governor gasket again (though not sure why Angel City's fix didn't take.)
mhoran wrote: ↑Thu Jul 20, 2023 2:47 pm
SouthTec thinks it's the prop governor or starter flange leaking, so I will bring the plane back to the overhaul shop once SouthTec has addressed the other items. Fortunately the plane is in NC now so the hop to GA is pretty short, and James (at the overhaul shop) thinks he can things quick if it's just the governor gasket again (though not sure why Angel City's fix didn't take.)
The starter flange is not exposed to engine oil.
Try the torque of the governor mounting nuts. You will probable find them to be far less that the prescribed 17-19 ft-lb
Rich wrote: ↑Thu Jul 20, 2023 5:28 pm
The starter flange is not exposed to engine oil.
Right, makes sense. I figured this meant there could be a crack. But the case came back with no issues so that would be surprising.
Rich wrote: ↑Thu Jul 20, 2023 5:28 pm
Try the torque of the governor mounting nuts. You will probable find them to be far less that the prescribed 17-19 ft-lb
This seems to be the most likely explanation. I will probably still fly down to Georgia regardless. Troubleshooting with other shops hasn't been particularly confidence inspiring.
Down at the engine shop in Georgia. They found that the prop governor was not properly torqued. They replaced the gasket and reinstalled with gasket maker and torqued per spec. After a 10 minute ground run there was oil everywhere. So it seems there's still an issue. Unfortunately the issue seems intermittent. We cleaned the engine again and performed two more ground runs (shorter) with absolutely no leaks. But the plan is now to send the governor back to the overhaul shop for warranty repair.
The leak doesn't seem to be coming from the gasket but from a "spacer" between the gasket and the governor itself. But we're unable to reproduce again so we haven't been able to pinpoint the leak. It'd be nice to nail down the source so we know we're replacing the right thing, but we haven't been able to reproduce.
There definitely is a potential leak path between the governor body and the base plate. They are held together by two machine screws plus the 4 through studs and nuts. I don't know for sure, but I suspect that there is an O-ring seal between them. Best to send back to the overhaul shop as you are doing.
The prop shop found the governor itself was leaking oil when they put it on their test rig. It will be fixed under warranty and should ship out by the end of the week. Hopefully I'll be back flying, leak free, soon.
It is amazing that an engine accessory fresh out of overhaul would leak. Don't they leak test them after the overhaul (rhetorical)? My overhauled prop governor didn't leak, but I couldn't get the static RPM above about 2560 with the lever pegged against the high RPM stock. Turns out that they used the wrong data on the drive gear ratio for the IO360-M1A to set the RPM lever on the splined shaft. Luckily, we were able to re-clock the lever without sending the part back...
The repaired governor is leaking again after just 6 hours. Looks like the bottom right again though there's some oil on the top right bolt as well. I'm not inclined to bring the plane back to the overhaul shop in Georgia but am not looking forward to paying another shop to troubleshoot. On top of that my cowling paint is flaking off at the exhaust yet again. I've just track of how many times I've had that repaired.
