I have done 2- FL250 engine rebuilds (1983, and 1978) and to replace the crank seals properly the case needs to be split. The seals are pressed in from inside out. It has a lip to stop the seal on both sides. Then the bearing go in after seals are installed.
Hint: Install seals in case
(Harwal seal # 25 x 55 x 10 type ADL: material NBR ,flywheel side)
(Harwal seal # 30 x 55 x 10 type ADL: material NBR ,clutch side)
Put both crank bearings in freezer at 0 deg for at least 1 hour before next step
(Koyo-JTEKT both are same bearing # 6306 “M1812” barcode # 4549250168727
After installing seals put both case halves in oven then heat oven to 200 deg Fahrenheit for 20 minutes
So at least 20 minutes AFTER at 200 deg F.
Take 1 of the halves out of oven and 1 bearing out of the freezer.
Bearing will literally fall into bronze bearing hole!
Keep case level until it slowly cools back down and bearing heats up, so bearing will not fall out or move.
Do the same thing to the other case half. THE SEAL WILL NOT MELT at 200 Deg!
Do not go above 220 Deg F with oven or seals will start to get soft!
Very important: Let the case halves cool slowly after installing bearings.
Warping of the case will happen if you RAPID COOL do not put in freezer to cool!
