The truck we have is a 1999 Chevy Suburban 1500, 2-Wheel Drive with a 350 vortec engine. We replaced the upper and lower intake manifold gaskets with no leaks for about a week and several hundred miles then it started leaking oil and then antifreeze after that. Does anybody know what the problem might be? Thank you for any help in advance.
Were the sealing surfaces on the intake and head(s) severely pitted?
How did you go about removing the remnants of the old intake gasket . . . in other words, how did you go about prepping the sealing surfaces? Exactly what tools did you use?
Did you torque the intake bolts, according to specs?
Where do the leaks come from? The intake? The rear main (oil) seal? The front of the engine?
BTW, how many miles on the engine?
There are UV dye kits you can purchase at auto parts stores that will help you figure out where the leaks are originating. Alternately, just thoroughly clean the engine from all deposits, then watch over the next week or two for leaks.