Date:May. 15, 2024
Hours:4
Brief Description:Takes longer to get the cowl and prop off than to replace the seal!
Chasing a small oil leak led me down the path of the nose seal. With the cowl off I noticed a small circular length of loose sealant (about 2″ long) sitting on the flywheel. With all the cooling air blowing inside the cowl its hard to pinpoint an oil leak so after pulling the cowling and scrubbing the engine many times I narrowed it down to the nose seal. Once the prop was pulled, my hunch was confirmed when I plunged my General Cotter Key Extractor into the seal and the seal spun effortlessly. There are a lot of online resources to learn about a seal replacement but I find it best to start with documentation from the manufacturer and go from there. In this case, Lycoming and their “Service Instruction No. 1324 D” ( TIME OF COMPLIANCE: Any time the front crankshaft oil seal is replaced) marked my starting point. I did make a few tweaks to the procedure to ease my mind about oil being on the seal when I glued it in place. The Lycoming procedure will have you brush oil onto the crankshaft and prop hub. I opted not to use oil to lubricate. I “lubricated” the prop hub with a plastic grocery bag and excluded adding any oil on the crankshaft out of an abundance of caution to ensure my seal was oil free when I glued it in place. This required extra vigilance when gluing the seal in place to ensure no bonding agent made contact with the crankshaft as it now would not have oil on it to prevent adhesion between it and the new seal.
See the cotter pin removal tool and a red plastic scraper I placed between the case and the cotter pin tool to pry against to protect the case from marring. I poked a hole in the center of the old seal, rotated tool, and pried out the seal.
Old seal after removal. I took a few bites out of the seal with a pair of side cutters. An o-ring removal tool was useful to manipulate the old seal while nipping it with the side cutters. Needle-nose pliers also helped.
In case you wonder how the spring works: the smaller portion threads into the other end. I liked this better than the Superior spring that had hooks. Don’t forget to reverse torque the spring 3 turns before reconnecting so it spins into itself.
I used a white handled Dollar Tree dental pick to clean the channel that the new seal’s “rib” would click into. I used the o-ring removal tools to scrap the rest.
Once the glue is removed I used multiple clean cotton rags doused in acetone to clean the surfaces of any residue. I used some maroon Scotch-Brite to clean the shaft.
Notice the Lycoming 13792 on the left with its spring. I liked this spring much better than the Superior SL13792 spring that had hooks that caught each other (spring union is at 9:00 in each seal picture above). I used the Lycoming seal as I liked it better.
This is the Lycoming seal. Not sure if you can get it locally from a Parker distributor in a pinch?
Out of my entire tool collection, these are the preferred tools I ended up using for the job. Not shown, new Costco 100% cotton towels, Acetone, and red Scotch-Brite, and ACS Oil Seal Installer Tool.
There are people who heat/bend plastic pvc pipe and cut a slit into it to replicate this tool. Not sure how that works, but this Propeller Shaft Oil Seal Installer from ACS works like a charm. Money well spent.
I heated some water in the microwave and put the new seal inside a glove and sunk in the water to heat it without getting it wet.
Make sure to orient the seal so that once it is installed it will be facing the correct direction. The grocery bag was my lubrication. Not shown is the white, plastic dental pick I used the handle off to coerce the seal over each of the six prop nut extrusions.
New seal in place. Waiting for spring installation and sealant to be applied.
Small end of spring threads into opposing end of spring once it is pre-spun. See Lycoming Procedure for details.
This is the approved sealant from the Lycoming Procedure that I opted to use of the approved compounds (Permatex® Optimum Max Flex Black (P/N 27037), Pliobond® #20, Pliobond® #25 or Dow Corning® 737 Neutral Cure Sealant).
The interior lip of the seal has to be coerced into place. Use two flathead screw drivers like you would tire irons to put on a tire. Make sure not to get the sealant on the shaft. Use one blade to hold the beginning point and the second to work around to get the interior lip started. Once the entire interior lip is started you can begin to push the whole seal into place.
The whole interior lip has been seated in this picture and it is slowly being worked into place.
Once in place I made sure the entire seal was seated before wipping off the excess with wide flat head screwdriver. There is a small chamfer on the edge of the seal. I filled this chamfer with sealant while wiping the excess off. This sealant chamfer is what I saw a piece of sitting on the flywheel. I love when you can find a smoking gun!