Alright so i am replacing my head gaskets and my intake manifold gaskets on my 2001 monte (3800 engine) and although i am replacing all the gaskets i would like some insight on what happened to the old one.
so issue #1. I had before thought that i blew a head gasket because i had oil and coolant mixing and showing up in my coolant fill tank but when i opened it all up the head gaskets were fine, but really dirty, lots of carbon and completely oily all over, so maybe the previous owner did not torque the head bolts properly? and everything just went everywhere over time..
and onto issue number
2. the intake manifold gasket **attached photo** this one was what i expected to see from a blown head gasket. in the photo the areas i have numbered, so what would have caused such deterioration on area #3? and #5 not as damages, and number 4 just under #3 whats would cause all that build up, is there coolant/oil or any fluids that travel through the intake manifold?
any help is much appreciated and if you know someone who can give insight please forward them this thread

 

As for questions in section #2:
- Nylon was a crappy gasket choice. Many people blame that damage on DEX, I've seen the same damage on 3100's using non-DEX coolant from day one. GM has had this problem for MANY years. When replacing the LIM gasket, get Fel Pro aluminum gaskets!
- When are port #3 and #5 different? Look at your intake. You will see the intake uses only ONE of the ports on both heads. In that pic, I am guessing port #3 was being uses by the intake and #5 met to a dead end (as the intake has no opening for it). Hot coolant passes through port #3, but is NOT passing by #5, so #3 is seeing more activity and movement. As for the remainder of the damage, once port #3 opened up, coolant moved along the rubber gasket and began doing more harm to the nylon.

As for questions in #1, did the last owner change the head gaskets? Normally you don't see head gasket damage until around 100K or more miles. When you removed the gasket, if you twist it slightly, did you find any cracks in it? It could be the materials of the gaskets broke down in ways you might no see OR if someone has replaced them before the heads were not flat (warp free) or improper torque was applied.