Intake gasket failure

Greetings,

I recently replaced the thermostat in my 1989 buick lesabre 3.8 FWD. Before then it was stuck in the open postion for the last couple of years I guess. The next day i developed a coolent leak in my intake. I replaced all the intake gaskets yesterday myself. Scrapped the old gasket and applied brake cleaner for smooth oil free surface. I used fel-pro gasket that go on dry and have orange rings. on the top and rear of the engine i used a small bead of black RTV sealent on all 4 corners. allowed it to sit 1 hours crank, reach operating temp then turn off and cure for 24 hours. The leaking side is sealed but now i have a leak on the other side. I used correct bolt torque sequence. Any suggestions or do i have to do the job all over again. Thanks

Is this a plastic (composite) upper intake manifold? I'm doing my 95 lesabre now. I've had a slight seep for years and It's just getting a little worse. I hear the intakes warp.You would think if it was going to warp it would do it sooner than 15 years later. I'm just changing the gasket first time around. Next time I'll replace the whole manifold. $149.99 at AZ.

I have the aluminum intake.

Not sure about alluminum. I believe it could still warp, ever so slightly. And cross- torquing little by little on installation couldn't hurt.

When you replaced the gaskets did you have any pitting on the heads and or the Intake? If they are pitted a little sealant would have gone a long way..

Where exactly are you leaking?