Bulletin No. SB-953
Powerhead
April 15, 1963
SUBJECT: New Drain Valve Plate and Gasket.
ENGINES AFFECTED:
MODELS - RX-11A UP (28 H.P.)
MODELS - RD-25D UP (40 H.P.)
MODELS - RDS-25D UP (40 H.P.)
MODELS - RK-25D UP (40 H.P.)
New type drain valve plate and screen assemblies along with new plate gaskets have
been incorporated in the 1963 28 and 40 h.p. models. The new plate with oval shaped
screens and its new gasket are shown in figure 1 compared with the round screen plate
and gasket previously used as shown in figure 2.
The crankcase pad on which the drain valve plate mounts has been redesigned to accept
drain plates with the larger oval screens. This new oval screen plate must only be
used on the redesigned crankcase. The plates can be accidentally interchanged, how-
ever, if the new oval plate is assembled on an older model without the redesigned
crankcase pad, trouble will result. The oil bleed off system becomes inoperative, the
engine will not idle properly, and often will load up and quit. (NOTE: This problem
can also be expected if the incorrect gasket is used with either plate).
Although the oval screen plates for the late 28 and 40 h.p. models appear alike, as do
the round screen plates for older 28's and 40's, they are different. The difference
is in the size of the drain hole, #55 drill (.052) for 28 h.p. and #60 drill (.040)
for 40 h.p. models with each plate having a different part number.
Always be sure to use the correct drain valve plate and gasket for replacement, and be
sure the correct gasket is used when doing service work.
JOHNSON MOTORS
R. Compton
Service Department
RC:eb
NOTE: Post on your RX 28 h.p., RD 40 h.p. and RK 40 h.p. indexes.