As I was trying to prepare for a work on the oilpan (possible leak) I managed to remove the exhaust manifold on my Honda Accord (year 1992). The gaskets between the manifold and the exhaust pipe looked quite bad, but though it could be reused until I got new ones. The manifold gasket itself looked fine. I cleaned off the surfaces and removed oil and dirt around, as well as removed a bolt that had been stuck in the manifold (from the manifold heat cover).

Then tightened it thorughly again. Started up and noticed after a while there were white smoke coming from behind the manifold somewhere.

I recently replaced the gasket of the head cover so, unless there are still oil or dirt around the manifold I don't think there would be an oil leak there.

Some of the bolt pins (not sure what it is called) got unscrewed from the engine body along with the self lock nut. Not sure if that need to be removed first.

So I guess the gaskets need to be replaced AND a torque wrench be used in case I have overtightened the bolts...

Should I be thinking about something else?