Thermostat Cover Problems???

On my 351W, we have replaced the thermostat covere 3 times, and tried a bunch of different gasket sealers and everything. It is constantly leaking antifreeze, mostly from the bottom end of the cover, and now it has started to leak on the top as well, And everyday we check on it, the excess antifreeze is in a huge puddle on the top of the timing chain cover. Is it because we are using a aftermarket intake, its a Edelbrock manifold, or just because we are buying cheap thermostat covers? and does any one know of a good brand, that i can buy, because im getting tired of constantly replacing it, and filling up the overflow tank all the time???
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First off, are you sure your gasket mating surfaces on the intake and the cover are clean and true? Also, are you sure that your thermostat is sitting in the thermostat housing groove and not hanging out preventing the surfaces from mating together with the gasket? I am currently using a chrome Ford Racing housing on my Edlebrock intake.

Yes we cleaned the surface really well, and it ran fine for about a month or so, but we only had it idling, and we hadnt drove it yet. but it seemed that once we started drving it, it started leaking worse and worse. But now, it doesnt just leak when its running and the temp is hot, it is constantly pouring out fluid. And we bought once of those thermostat covers, with the grooves for a rubber gasket. I think this might be the problem, and need to go to a regular gasket, and then hopefully will get a better seal? :shrug:
you guys have this pretty much covered already, i was just thinking maybe he can just use 2 gaskets.
i did that once on a 77 T-bird and it out lasted the car lol

Alright, il have to check out Autozone and see if they have it. First im gonna try the old thermostat cover again, but if it doesnt work again, should i go with a 45 degree neck or 90 degree? Is there really a difference in flow or whats the difference?
I do not have the Mr. Gasket housing, I have the actual Ford Racing housing. The 1965-1973 cars take the 45 degree housing. The 90 degree is intended for the Fox and newer 5.0 cars.

See we just bought a cheap one from Autozone, and it had the o ring style gasket built-in, but its not even the 45 degree, its just somewhat bent, into an arch, its not even a legit thermostat cover. But the car is just for daily driving, and after getting some miles on our new 351W and break it in, then im going to bring it to the track, after i get some new tires, the grandma tires on it now, aint gonna cut it. And i think im just going to take the thermostat cover off, and sand it down, and get all the excess sealer off, and then try to not go so heavy on the gasket sealer, and see if that helps any.
I've been using an aluminum housing for a few years on my 302 with the weiand intake without any problems. Make sure the thermostat doesn't slip between the housing and the intake when you install it.

For example:

Classic Mustang Parts On Line Catalog - Product Description: 64-73 THERMOSTAT HOUSING C5OE-8592-A

the only tstat housings that use the "O" ring gasket is the chrome ones, and that is because they had a real tendency to leak, at least the cheaper ones did. i personally use the stock aluminum ones as every chrome one i have tried leaked. use the stock housing and permatex #2 sealer on both side of the gasket, use a THIN coat on both sides. and bolt it together. do not over torque the bolts either, and make sure the bolts are short enough for your application. sometimes the bolts that come with the chrome housings are a bit too long and thus you dont get the housing tight enough.