When putting an old water pump on the replacement engine, I checked the gasket and it looked good, no reaps or tears, the rubber was not hardened. So I used the old gasket, but the water pump is leaking now. I'll check the bolts, might have forgotten to tighten them up or possibly the gasket is of threinstall the pump.e groove. Either way, this time will buy a new gasket and reinstall the pump. As a rule, should I use a new gasket every time I take off the water pump?

 

Always always always put a new gasket on pretty much anything you've disassembled when putting it back together again.