Mercury 25 EFI Service Manual page 284

Cylinder Head
4. Thread a M10 ‑ 1.5 bolt into the bottom of the intake rocker shaft and remove the intake rocker shaft from the cylinder
head.
5. Remove the bolt from the intake rocker shaft and repeat the procedure for the exhaust rocker shaft.
6. Remove the camshaft by sliding the camshaft toward the bottom of the head. Do not damage the camshaft bearing
surfaces.
7. Remove the upper camshaft seal.
a
8. Compress the valve springs using a valve spring compressor.
9. Remove the keepers, upper seats, springs, lower seats, and valves.
Valve Spring Compressor
NOTE: The valve seals are not reusable.
Page 4B-12
a -
b -
b
a
11486
a - Camshaft seal
11488
© 2016 Mercury Marine
M10 ‑ 1.5 bolt
Intake rocker shaft
91‑809494A1
90-8M0105568 eng MARCH 2016
11502