[badidea]

If you are having to replace the water neck and original equiment doesn't matter, I see many of these new fangled billet thermostat housings use an o-ring instead of a gasket.

[SalineHornet]

Originally Posted by Bob A

Yes, this is what the water pump mates up to and is pretty common for an anti-freeze leak. And when it does leak it's hard to find. I just changed mine (66 mustang 289) about 6 months ago. Same problem, loosing anti freeze, it was puddling up behind the water pump & timing change cover. After removing the cover I found corrosion on the gasket mating surfaces. You can try and clean it up, but I opt to replace it. Good Luck

Just to follow up. You It's the timing cover that is leaking.

Seems like something is always leaking.. lol.