Daf said:
People strip or crack their cases when they continue to crank 20 ft lbs (or whatever your spec is) on the used washer. I was buying new washers from Kawi for $3 a shot for awhile until I decided to try the used washer again - no problems so far.
The reason an old sealing washer will crack a case is because every time you re-use the washer, it pushes a little more of the washer into the chamfer of the drain hole. Most drain holes have a little chamfer before the threads start. When you re-use the aluminum washer, it forces the washer into the chamfer. After a while, this forms the washer into a little wedge. Kinda like the shape of a funnel. If you re-use the old washer enough times, the force from the washer will spread the drain hole and cause it to crack.
It's best to use the correct OEM part to avoid this problem. The cost of repairing or replacing your engine cases is a lot more than the cost of a washer.
If you insist on using aftermarket sealing washers, you can usually find them at an industrial hardware store. Keep in mind, not only is the size 'diameter' of the washer important but the thickness and hardness of the material is very important.
Just my $ .02 :cool: