2001 Cherokee Sport that had a cracked head and blown head gasket.

I replaced the head with a Nutech 2A34 cylinder head and put a Fel-Pro MLS gasket (26211PT) between the block and head. While I was in there, I replaced the water pump, Thermostat, and thermostat housing. I used new head bolts and sealed the one that goes in the water jacket. I also put new rocker assemblies and push rods. Used a torque wrench and torqued head bolts to 110# (except the one that goes in the water jacket that was put to 100#). The rocker assembly was torqued to 19#.

Went to start it and there was a loud banging noise that got quieter, but still noticeable after a minute or two. When the RPMs are pushed to 2K it is not noticeable.

More concerning, after a minute or two a large (very large) white plume of smoke billows from the tailpipe. I noticed that there is a spray of what appears to be coolant spraying out of the tailpipe as well.

I opened the oil cap and noticed that the oil is milky, signaling that coolant is mixing with the oil. This was not present when prior to the cylinder head and gasket replacement. Prior to this it only produced white smoke.

I changed the oil/ filter when I did this work, so it is not left-over coolant in the oil from the swap.

When I cleaned the engine block deck, I did the best I could. It is not perfect, but it is relatively smooth. There was some minor pitting, but all the old gasket was scraped off. I used a Scotch-bright bristle brush and pad. There was some discoloration that I did not manage to get off, but it felt smooth to the touch but did not have a mirror finish…

I checked for level with a straight edge, and it appeared fine. I could not see any cracks and looked as closely as I could.

Should I scrap the whole thing, try another gasket, or what. If I try another gasket is there a more forgiving one. The Fel-Pro 530 SD appeared to be squishier. Would that be more forgiving? Should I try to polish to a mirror finish?

 

No way to know until you take it apart again but the "loud bang" , coolant in the oil, coolant in the exhaust suggests it's going to be more than a not quite sealed head gasket.
​​​​​​Gotta take it apart but sounds like something broke.

Bummer.. .

 

Sounds bad. Compression test? You don't want a mirror finish, you actually want a very slightly rough finish which will hold the gasket in place better.