97 Monte carlo (3.1) Multiple issue, please help!
97 Chevy Monte Carlo with the 3.1 motor. Recently have a antifreeze smell coming out of the tailpipe, and sometimes a rotten egg smell. Cat doesn't seem to be bad yet, and oil dipstick isn't a milkshake so I don't think it'* head gasket...However when I pulled radiator cap off it was pretty gunky and kinda had same milkshake you'd see from head gasket. I'm thinking the lower intake is going? Anyone else agree? I know it'* somewhat common.
The other issue i'm having is tapping. It started off hardly noticeable when I would cold start and go away, than it got a little louder and would go away, not it'* not going away at all. I'm fairly certain it'* all top end, not bottom end knocking. I'm thinking sludge and stuff might be building in the engine from the antifreeze (hence lower intake), not enough to milkshake but enough to cause problems. I've also been told the tapping is common too though, soooo i'm not sure.
So, should I go ahead and replace the intake gasket (I've worked as an apprentice for awhile so I can do the work, just suck at Diag) and than maybe an engine cleaner + oil change? Cause I just did an oil change w/Lucas and tapping still there...I can roll the push rods when I get to the lower intake gasket and see if any are bent and replace, but I reallllly don't know how to tell if it'* a bent valve making the tapping...any adice will be welcome. Thank you SO much.