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Lycoming Galley Plugs

MartinPred

Well Known Member
After a two-year rebuild, the good news my Lycoming O-360-A1D is back to together on my RV-4, and started up just fine with no oil leaks. My tappet bodies had corroded, damaging the cam, and forcing me to do a complete rebuild, which I decided to do myself. I was only able to work a few hours a week, so it took me the last two years to complete.

I followed the Lycoming overhaul manual line by line, and had an A&P buddy ofmine looking over everything at key steps.

But the bad news is, I think I missed something. After two engine runs, with the oil bypass valvle cranked all the way in, I'm still getting very low oil pressure--no higher than 21 PSI at 1800 RPM. Maybe it's a bad guage, but I think it's something else.

I went through all the photos I took during reassembly, and I think I forgot to install the galley plugs in the accessory case. The only photos I took of that area all show the plugs missing, and I don't remember putting them in.

So the question: does anyone know a technique to install those plugs without pulling the motor and removing the sump and accessory case? It looks like there might be enough clearnance through the mag holes to get them in there. But then how do you torque them, and is there a good way to make sure you don't accidently drop them into the sump?

After all this work, it would be a shame to still be weeks away from flying.

Thanks,

-Matt
N402BD
 
I would call Divco for the location and number of clean out holes for your engine. I know there is one on each end of the two main oil gallies. The fore will be visible and the aft are only accessible with the accy case removed. I think there are one or two additional clean out plugs, but not really sure. Can't remember that far back when I rebuilt my 320. I could tell you where they are on the 540, which is in pieces in my garage, but that won't really help you.

Most overhaul shops leave the galley plugs out, but include them in a bag and expect the rebuilder to install them. They do this for the mechanic to inspect the gallies. Were there any "extra" clean out plugs in the bag they sent you? That would be a clue that you missed one.

There is no clean out plug in the interior of the accy cover itself.

Best of luck. It sure seems like you left out a plug from the low pressures. Did you check the clearance on your journal and rod bearings? The wrong size bearings could cause this as well, especially the journal bearings.

While I have no experience with this, I have to wonder if the pump could actually produce 20 PSI with two clean out plugs missing. That's a pretty significant leak. Maybe Mahlon could answer that. Have you pulled the mags to confirm? You should be able to get a mirror in there to see.

The accy case can be removed without pulling the sump, but requires some care in sealing up the joint created in the sump gasket on reinstall. Removal of the sump will increase the likelihood of no leaks. I have no idea if the plug can be installed through the mag hole, as I have never really looked for that. You may be able to pull it off with a square head plug instead of the typical internal hex plug. The plugs are NPT, so no need for a torque wrench.

Larry
 
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Plugs

There is a torque value for the plugs. Use a torque wrench, also the proper sealant as called for in the OH manual.
Hope you didn't run the engine very long at 21#. Minimum for idle is 25#.
 
I'll take a look

The engine has only run a couple of minutes and was well-oiled during rebuild. I checked those bearings and journals during assembly. The Lycoming manauls goes into great detail on the clearances, but doesn't even mention those plugs. I guess that's just one of the things you're supposed to know.

I'll pull the mags this weekend and see if I can put eyes on the galleys, and also see if I can get to them. I'll also look around to see if I have a bag of plugs from when the case came back from the shop.

If I have to pull the engine and remove the accessory case cover, I guess that's what I have to do.

Thanks,

-Matt
 
The engine has only run a couple of minutes and was well-oiled during rebuild. I checked those bearings and journals during assembly. The Lycoming manauls goes into great detail on the clearances, but doesn't even mention those plugs. I guess that's just one of the things you're supposed to know.

I'll pull the mags this weekend and see if I can put eyes on the galleys, and also see if I can get to them. I'll also look around to see if I have a bag of plugs from when the case came back from the shop.

If I have to pull the engine and remove the accessory case cover, I guess that's what I have to do.

Thanks,

-Matt

The manual doesn't mention the installation of the plugs because they don't require or outline a process for removing them and cleaning the gallies during the overhaul. Therefore, no mention of installing them.

Best of luck.

Larry
 
0360-a1d has five galley plugs. You will not install them without pulling the accessory case. Watch this lycoming overhaul video. There are two plugs in the front and three in the back. I have overhauled two of them this year. Scroll to 15:05 for galley plug install video.

https://youtu.be/n-26eqLc4pQ

Part number 13.

47-FC9719-2-AD8-4-BFD-B8-E9-1-D46-B603-A91-D.png
 
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Same Video

I watched that very video when I was putting everything together. So maybe I did. I definitely have the three external plugs installed.

I?ll pull the mags this weekend and check the internal ones.

-Matt
 
There are two number 13’s on the right rear case. If you missed one, i bet that is the one. It goes in at a 45deg angle. Part number 14 is either a plug or prop control line. The two rear plugs are actually under the accessory case flange. You will not be able to see them. I highly doubt you could install the other one with the gears in place.
 
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In your OP, you state:

But the bad news is, I think I missed something. After two engine runs, with the oil bypass valvle cranked all the way in, I'm still getting very low oil pressure--no higher than 21 PSI at 1800 RPM. Maybe it's a bad guage, but I think it's something else.

Before I began tearing down the engine, I would make certain that it is definitely NOT an indication issue. I'd take oil pressure readings on several different ports with several different oil pressure gauges!!

Or trash in the oil pressure regulator valve. Or, .........
 
Sometimes, some sort of assembly pieces (assembly grease, sealant particles, bits of gasket) can get lodged in the pressure relief valve. That sometimes just comes out on a subsequent engine run and everything is fine. Other times, you may need to remove the pressure relief valve completely to clean it out. But, something lodged in the seat of the pressure relief valve will cause a low pressure indication. Oil pressure is still likely normal throughout the engine, but the indication is inaccurate. It?s pretty easy to pull it out and check it.
 
I had same problem years ago, plugs were removed during case overhaul, were not installed. I got the accessory case off the plane in a Mooney e model. Can be done.
 
A borescope of some kind could help determine if the plugs are installed - through a mag hole? I don't know if this was an issue for you, but I can see how overhauling an engine over a long period of time could be problematic. Would you remember at the end of 2 yrs what you did in the beginning, vs if it was a week ago? Anyway, you will remember next time :eek:
 
Update: Missing Plug Found

After some hunting around with the borescope through both mag holes, I determined that I had indeed missed one of the three plugs.

Here's the left one that I installed during the rebuild:

4EFFA915.jpg


Here's the empty hole on the right side:

4EFFB0F5.jpg


After a doomed attempt to get the plug in without pulling the accessory cover (there's a bit of space in there to work, but the angle is impossible), I pulled all the accessories and then removed the cover. Turns out there's plenty of room on the RV-4 to do this once you remove the accessories.

Here's the plug properly intstalled on the right side.

IMG_204636.JPG


That was a far as I could get this weekend. Plus I had to order new gaskets. So next weekend I'll put everything back together and try again.

Thanks,

-Matt
N402BD
 
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