I had a fun couple of hours yesterday changing the water pump on my P38.
It started leaking after I flushed it last week, not surprising considering the shit that came out of the radiator when I first got it.
There was a coppery looking paste coming out. AFAIK thats a stop leak product.
You can see the shit in the gap for the o-ring.
Its also been replaced with a pump with a metal impeller.