New crankshaft seals and bearings?

[digitalsam]

An auto mechanic told me that it would be a real good idea to replace the seals and crankshaft bearings before I reassemble the engine. The bearings look ok to me, but I am no mechanic.

Has anyone who has rebuilt an engine replaced or reused the bearings and seals? Can you tell me why you did what you did and... if I do need to replace them, do you have a source?

[trbig]

If you have any copper color showing on the crank bearings, replace them. If not.. then I wouldn't. The ones that seem to get the most wear are the outside ones next to the crank seals.

Most people I know replace the seals even if they don't leak yet, simply because they are or are nearly 30 years old. I think you've gotten your money's worth out of them. They are @ 5-6 bucks each to replace. BUT.. they can be replaced later if they start leaking without removing the engine or anything.. you'll just have to pull the rotor and your pickup cloils again. Kind of a PITA... so basically just easier to do now while you have it apart.

Try to find seals that have a double lip on the inside. Most any shops that specialize in bearings and seals can get them. The sizes are 32x45x7.8 and 32x48x7.8. First # is inside diam, second is outside diam, third # (7.8) is thickness. You won't find a 7.8, so just get an 8.

Tod

[Ivan]

Tod has it right, If there is copper showing, Time for new ones. If you do replace them, You'll want to mic the journal and get an idea of what amount, if any, undersize you'll need. Yamaha used a color system in which color codes represented the amount of undersize. I have no idea which color means what.

When you get the new bearings, it's a good idea to check them with plastigage. FOr those that don't know, its a piece of plastic thread that squishes out when the bearing cap is tightened, and the width of the squish indicates the clearance. Simple, Effective, Cheap.