I have a coolant leak that has been a little tricky to track down. It isn't a steady leak, and it seems to pour out only after the van sits for a while (all day or over night) and I find a puddle on the pavement. Even when a friend used his pressure tester nothing came out. After pouring in some UV coolant dye, I have narrowed the leak down to the left (driver) side just above the transmission. The lower radiator hose goes to a metal pipe which is connected somewhere to the engine just above the transmission where I cannot see. It looks that it is leaking at the point or vicinity of where this metal pipe connects to whatever. Here's the kicker: the 'Haynes Repair Manual' says, "The 3.0L V6 engine uses metal piping beyond the lower radiator hose to route coolant to the water pump, which is located in the V of the cylinder banks." However, the belts and everything are on the opposite side (right) of the engine! Could someone please tell me what this metal pipe connects to? Could this be as simple as a gasket or o-ring? Is there anything else in that vicinity that could be the cause/source of the leak? I am also curious as to why this is so intermittent. Many thanks!

 

]water pump runs off the timing belt, back of water pump is the tube that goes under the intake and comes out above the transmission. http://t2.gstatic.com/images?q=tbn:A...RuSQjRSVXrPGJw

where did you notice the puddle when it leaked? I'll put money on the water pump is leaking.. VERY common and when they start leaking they do what you are saying... sometimes it leaks and sometimes it doesn't

 

Just like sapporo had said, the crossover tubes could be rusted out or the o-ring seals are bad.