[b-man]

No sealant needed.

However a somewhat liberal application of anti-seize would be wise, those two fasteners as well as the two above are notorious for rusting and breaking off when servicing the water pump or timing chain.

You have to make good and sure that the gasket surfaces on both the block and timing cover are clean and flat. Leakage of coolant into the engine internals can happen here, one of the design faults of this particular engine unfortunately. If your timing cover is corroded excessively replace it.