I just did a huge timing belt and seals job that included replacing the coolant in my 1997 accord with the f22b2 engine. The drain bot washer fell out, and I didn't notice it, so I put back the drain bolt without its washer. I used plenty of hondabond on the threads of the drain bolt per the factory manual, and I'm wondering if I can get by without the washer. Obviously I would like to avoid the hassle as well as avoid wasting coolant. Will the hondabond and a properly torqued bolt be sufficient?
Maybe. For a while. Perhaps. If the plug loosens or falls out, the engine may be damaged, you won't have a drain plug or coolant, and the car will be immobile.
Solution: get a big plastic tub. Drain coolant into the tub. Remove drain plug, add washer, reinstall plug. Refill cooling system using the coolant you just drained. Bleed the cooling system.