I have a coolant leak in my '90 legacy like I've never seen before. When the car is running (cold or hot) it doesn't leak. Sometimes (not all the time) when it's parked overnight, there will be a puddle and antifreeze right under water pump. The car has 180k on it and is due for a timing belt and water pump. I've never seen a pump only leak when it's cold, and then only leak sometimes. I'm assuming it's a seal in the pump, and I'm planning on replacing it one of these weekends. Anybody else have any ideas what it might be? Thanks.

check the o ring that goes to the waterpump from the radiator hose. my 86 gl did the same thing untill i replaced it.what i figured out was when car was running the pressure was enough to seal o ring but when it was off no pressure so it could leak !

It's a common method of failure for a mechanical seal with worn down rotating faces to leak when stopped and leak less or not at all when running. The pump replacement you are planning will take care of this problem. I would naturally look over the pump related seals and gasket contact surfaces in case there is another problem.

Check the impeller on the water pump before buying it. When I was debugging my cooling problem I changed the water pump. My old one had a stamped sheet metal impeller, while the new one had a nice cast impeller. The improvement in water flow almost was enough to fix the problem, even though it was the radiator that really was the largest problem.

 

 

 

Stamped sheet metal impellers suck.