i have just takin off my runners for the second time . there getting polished. under the runner above number 6 cylinder there is oil i believe.it just so happens that i have a knock in number 6.if the intake had a crack would ihave problems with this cylinder.i am taking the engine out soon to check the engine. the engine also smokes alot when warmed up. this is in a 90 iroc with 5.7. HELP ANYONE.

 

I would check the bolts for the intake first... They thread through a flange on the head into the lifter valley.. Hard to explain but if you take it apart you will understand. When the intake bolts are installed they have thread sealer on them and over time it can breakdown. If it does the oil from the lifter valley area and runoff from the heads can wick its way up the bolt threads and onto the surface of the intake manifold.... Common problem. Hope this helps.

 

yeah try sealing the threads first

i always use plumbers pipe thread dope in a tube or on a brush works great

oil works its way up the bolt threads and sits in puddles on the intake

the four middle bolts anyways

the other 8 bolts thread into either water or nothing but sealed metal pockets, dependong on the end of the head they ar elocated at


very common issue
see it all the time