Harley-Davidson Dyna engines deliver oil from the hydraulic lifters to the top end through the hollow pushrods. Oil is transferred to the rockers via an oil passage and the oil lubricates the rocker bushings and valve tips. Return oil drains through oil passages in the cylinders and through the pushrod covers. The covers have three rubber gaskets called quad-seals that, when compressed by the pushrod cover clip and spring, contain the oil and air/oil mist that is evacuated from the rocker box. The quad-seals can get old and brittle, which can lead to a serious oil leak.
Lift the rear wheel off the ground with the bike jack. Shift the transmission into first gear. Remove the pushrod clips from the spring-loaded pushrod cover with a pair of pliers. Collapse the pushrod cover to expose the pushrods.
Roll the rear wheel forward until the front two pushrods are no longer being lifted by the cam. Remove the rocker box cover bolts with an Allen wrench. Remove the cover and spacer from the engine.
Remove the lower rocker box bolts from the box with a socket and ratchet. Back them each off 1/4 turn at a time, in series, until the rocker box is no longer stressed. Remove the box bottom. Repeat these steps for the rear cylinder.
Lift the pushrods and covers up and out of the engine. Do not mix up the pushrods as each one is slightly different in length. The rods are colour coded, with the order set from front to back as purple, blue, yellow, green.
Pull the old seals from the bottom of the rocker boxes, lifter blocks, and the middle of the pushrod tubes with your fingers. Install the new quad-seals into their locations.
Reassembly is the reverse of disassembly. Torque the 5/16-inch rocker box bolts to 15 to 18ft./lbs. Torque the 1/4-inch rocker cover bolts to 10 to 13ft./lbs. with a 3/8-inch torque wrench.