Interesting. Other than an early leak out of the rear breather screw caused by poor assembly at the factory, my FLHTCU has been completely dry of leaks in 16k miles. Until about 2 weeks ago the rear rocker box started seeping, at the right rear area of it. I suppose in the old days this would have been considered normal. The rest of the motor and tranny are completely dry. As for the blow-by, my engine uses oil (Syn3) at a rate of about 1/3 qt in 5k miles. Well within normal. And my air box gets very little oil in it. Maybe HD improved the breather filter to keep more oil in the motor than the air box?

 

I did this repair myself and thought I'd post my experience with it.

There is very little clearance between frame and rear cylinder. Before beginning, I bought two dog bone torque adapters for working in that space with a torque wrench. In the end, I wasn't able to get at the three left side rocker cover bolts even with the the 7/16 dog bone. I tightened all six rocker cover bolts by feel, using a small box end wrench. If anything, they are under torqued.

After getting it all back together, fuel tank back on, seat installed, ready to ride, I cranked it and heard a loud tapping. It didn't go away after ten seconds so I shut down and took it apart again, down to the Rocker Support Plate to check my work. I pulled the pushrods to make sure I hadn't somehow reversed them. I hadn't. Everything looked perfect, so I suspected the rocker assays had gotten a bit dry. I had noted no new oil on the rocker arms. I should have given it a bit more run time. Now I know.

This time, I hand oiled the rocker shafts before reassembly, and put some on the tops of the pushrods. I reused the fresh rocker box gasket that was new before I took it off the second time. Got it cranked again, and poosh no more tapping. I have put a hundred highway miles on it since yesterday and there is no leak. However I won't be surprised if that twice-torqued rocker cover gasket starts leaking soon.

My "leak" was so minor I could have just monitored it with a dab rag. Still, I'm glad I did this work now. I feel more invested with this bike. Riding it is more and more something I have to do every day.

 

My 14 had to have the rear rocker box gaskets replaced at about 16k miles.

 

Glad you got it fixed, I added the rocker cover bolts to my service checklist since I found one loose causing a minor leak on the rear left middle side.