I was having cooling problems so I took the radiator in for a good cleaning and checkup and bought a new waterpump from Advance. They _said_ it was compatible and it looks the same, fit properly, and all the connections slid right in.

However, it is leaking only from the top connection to the block. All the other connections are fine. My friend and I installed it twice. First time we forgot to clean off the old RTV sealant from the block side of the connection and it leaked. The second time we put a TON or RTV on the top, the gasket to the block was fine but we put more RTV on that as well. When we put the bolts back on I pulled up on the pulley HARD to get the connection on top tight. A friend of his at work who used to own an old Volvo suggested it. We let it cure overnight and came back to fill the system and it leaked again from the same place.

Is it possible that the new waterpump is a fraction of a mm lower than the old one? Or is there something I'm neglecting (or a trick) to get that seal really good and tight at the top? I'm going to get a new gasket and try the old waterpump again but I'd like to use the new one if it will work.

Anyone else have experience with this? (PS thanks for all the other help - this forum is GOLD)