Hey VAF-ers,
So I decided to come here and post some recent findings on my 290 SMOH (completed in Spring 2019) O-320-E2D on my RV-4. I bought the airplane in January 2016. It had around 900 SMOH. Flew the snot out of it the first two years and always had a damp engine during those years. A drip was always found on the starter and alternator bracket and the airbox was always greasy along with the carb. Cylinder work was needed in 2019 and I elected to completely overhaul it at that time. It was done at a certified shop in TX yellow tags on all reused components. From about hour 30 on the new engine, I noted that the bottom of the engine was damp yet again with oil. At that time, I was working as an engineer at Lycoming engines so I wasn't too concerned. Surely they have a fix for this and I would get discounted parts if it got worse. So I flew it some more with a continually slightly damp lower engine. I then proceeded to get laid off from Lycoming along with 30% of employees at the company in July 2020 due to covid cutbacks. (bye bye discounted parts and easily available solutions. I knew I should have bought a new engine while I was there...)
Fast forward now to January 2021. I moved to Milwaukee, WI and did a little sub zero flying out here and found a more significant amount of oil now leaking on post flight inspections having switched to a multi viscosity oil from aeroshell 100W. I heavily cleaned and leak checked it and determined it was coming from the crankshaft seal. I inspected the superior split seal which was installed at overhaul with plyobond. It was well adhered to the case and absolutely not leaking around the seal... uhoh... ya you see where this is going.
Turns out that the leak is coming from between the seal and the crank itself! How could this be?! Having worked for Lycoming, I immediately went to the O-320 Table of limits and noted that the diameter interacting with the seal uses the same leader line on the new part print as the front main bearing (2.375" in diameter). I took a measurement on my crank in the area that interacts with the seal. It measured 2.368" Not good. I called a lot of friends at Lycoming and had a lot of talks. It would appear that this diameter at the seal can be polished/ground up to .010 under nominal but it is EXTREMELY convoluted in the literature and table of limits. I called the repair station that yellow tagged the crank and they verified that it measured 2.368 as well and that they did not grind or polish that area at all during my overhaul work. (This is the 3rd run on this crank). So now what?
I have all the tools required and a few LW-13768 seals and I elected to simply install a new solid seal per SI1324C and hope for the best. I completed the job last night and left a heat lamp on my work to let the Dow Corning 737 set up before leak checking later this week. After completing all this work I, have not yet done a leak check while I am writing this so I will be sure to do a follow up post. I wanted to note a few things though that I have learned so far to help others:
1. - Ask your repair shop and overhauler what that dimension the crank measures in the area that interacts with the crank seal overhaul! I never would have guess how large of a pain it would be.
2. - Lycoming does not design a seal that will work with a crankshaft that is smaller than 2.374" OD in the area of the seal... Even though it still meets overhaul limits! I am not happy about this.
3 - What are the solutions? I did not try this yet but I wish I had thought about this before completing the job last night. I read another thread here where someone recommended cutting a few coils off the female side of the inner spring that goes in the crank seal before twisting it together and installing it in the seal on the engine. From what I can see, this is the best solution and will help apply more pressure on the undersized crank.
At least I now know another cheaper fix to try if this continues to leak before I have to pull the engine and split the case to replace the crank. If anyone wants to see pictures I will happily email them as it is easier than trying to post them here.
...all to prevent a few drips of oil. Some days airplanes are really frustrating.
So I decided to come here and post some recent findings on my 290 SMOH (completed in Spring 2019) O-320-E2D on my RV-4. I bought the airplane in January 2016. It had around 900 SMOH. Flew the snot out of it the first two years and always had a damp engine during those years. A drip was always found on the starter and alternator bracket and the airbox was always greasy along with the carb. Cylinder work was needed in 2019 and I elected to completely overhaul it at that time. It was done at a certified shop in TX yellow tags on all reused components. From about hour 30 on the new engine, I noted that the bottom of the engine was damp yet again with oil. At that time, I was working as an engineer at Lycoming engines so I wasn't too concerned. Surely they have a fix for this and I would get discounted parts if it got worse. So I flew it some more with a continually slightly damp lower engine. I then proceeded to get laid off from Lycoming along with 30% of employees at the company in July 2020 due to covid cutbacks. (bye bye discounted parts and easily available solutions. I knew I should have bought a new engine while I was there...)
Fast forward now to January 2021. I moved to Milwaukee, WI and did a little sub zero flying out here and found a more significant amount of oil now leaking on post flight inspections having switched to a multi viscosity oil from aeroshell 100W. I heavily cleaned and leak checked it and determined it was coming from the crankshaft seal. I inspected the superior split seal which was installed at overhaul with plyobond. It was well adhered to the case and absolutely not leaking around the seal... uhoh... ya you see where this is going.
Turns out that the leak is coming from between the seal and the crank itself! How could this be?! Having worked for Lycoming, I immediately went to the O-320 Table of limits and noted that the diameter interacting with the seal uses the same leader line on the new part print as the front main bearing (2.375" in diameter). I took a measurement on my crank in the area that interacts with the seal. It measured 2.368" Not good. I called a lot of friends at Lycoming and had a lot of talks. It would appear that this diameter at the seal can be polished/ground up to .010 under nominal but it is EXTREMELY convoluted in the literature and table of limits. I called the repair station that yellow tagged the crank and they verified that it measured 2.368 as well and that they did not grind or polish that area at all during my overhaul work. (This is the 3rd run on this crank). So now what?
I have all the tools required and a few LW-13768 seals and I elected to simply install a new solid seal per SI1324C and hope for the best. I completed the job last night and left a heat lamp on my work to let the Dow Corning 737 set up before leak checking later this week. After completing all this work I, have not yet done a leak check while I am writing this so I will be sure to do a follow up post. I wanted to note a few things though that I have learned so far to help others:
1. - Ask your repair shop and overhauler what that dimension the crank measures in the area that interacts with the crank seal overhaul! I never would have guess how large of a pain it would be.
2. - Lycoming does not design a seal that will work with a crankshaft that is smaller than 2.374" OD in the area of the seal... Even though it still meets overhaul limits! I am not happy about this.
3 - What are the solutions? I did not try this yet but I wish I had thought about this before completing the job last night. I read another thread here where someone recommended cutting a few coils off the female side of the inner spring that goes in the crank seal before twisting it together and installing it in the seal on the engine. From what I can see, this is the best solution and will help apply more pressure on the undersized crank.
At least I now know another cheaper fix to try if this continues to leak before I have to pull the engine and split the case to replace the crank. If anyone wants to see pictures I will happily email them as it is easier than trying to post them here.
...all to prevent a few drips of oil. Some days airplanes are really frustrating.