I recently installed the Dynon supplied 5/8-18 UNF (Dynon P/N 100409-001) as described in the manual. This sensor has straight threads (like a bolt) and my accessory case, like most Lycoming cases has pipe thread so there was little doubt that it would leak. The manual calls for a crush washer but even with the proper crush washer, you still have the wrong threads to deal with.
If the sensor backs out in flight at the very least you will have a very nasty oil leak to clean up. What's worse is the very real possibility of serious engine damage and a forced landing.
If you installed this sensor in your engine and it didn't quite fit please take a close look at how it fits and does it leak. If you have this sensor in an airplane that you bought you should be concerned as well. I've done a lot of searching on several different forums and found comments like "it leaks a bit" or "I couldn't ever get it to stop leaking".
I called Dynon about this as well and was told by the person I spoke with that he hadn't heard of a problem although he admitted he hadn't actually ever seen an accessory case on a Lycoming engine, searching this forum found the same thing, they hadn't heard of a problem.
The fix is relatively easy. Call Dynon and order the smaller 1/8-27 NPT (Dynon P/N 100409-000), it's a $20.00 part. This sensor HAS pipe thread but may be too small for the accessory case. If it is simply get a brass bushing (reducer), a $3.00 part. Mine required a 3/8 to 1/8 bushing and does not leak.
Not trying to wave a red flag here although, I do think Dynon needs to take a serious look at their instructions as well as the suitability of the sensors offered. If it's not the proper thread, it's not the proper part. Just don't settle for close enough or even a small oil leak, it could bite you later.
If the sensor backs out in flight at the very least you will have a very nasty oil leak to clean up. What's worse is the very real possibility of serious engine damage and a forced landing.
If you installed this sensor in your engine and it didn't quite fit please take a close look at how it fits and does it leak. If you have this sensor in an airplane that you bought you should be concerned as well. I've done a lot of searching on several different forums and found comments like "it leaks a bit" or "I couldn't ever get it to stop leaking".
I called Dynon about this as well and was told by the person I spoke with that he hadn't heard of a problem although he admitted he hadn't actually ever seen an accessory case on a Lycoming engine, searching this forum found the same thing, they hadn't heard of a problem.
The fix is relatively easy. Call Dynon and order the smaller 1/8-27 NPT (Dynon P/N 100409-000), it's a $20.00 part. This sensor HAS pipe thread but may be too small for the accessory case. If it is simply get a brass bushing (reducer), a $3.00 part. Mine required a 3/8 to 1/8 bushing and does not leak.
Not trying to wave a red flag here although, I do think Dynon needs to take a serious look at their instructions as well as the suitability of the sensors offered. If it's not the proper thread, it's not the proper part. Just don't settle for close enough or even a small oil leak, it could bite you later.