Do I need to replace this wooden lintel? Help / Advice needed please!

[JP_]

Stripped tiles and plaster off old kitchen wall. Part of wooden lintel above WC door is rotten. Not too bad, i.e. cannot push a screwdriver in. Everything is solid. Can I treat the wood and fill around it, or should I get it replaced? It's a bungalow, nothing above other than joists. As the door frame is knackered I am thinking about removing it and putting a new frame in.

This wall is between the old kitchen and old shower room, and the wall to the left was external, but now there's an extension. It is now an internal lobby, and shower is being replaced with occasional bath, so it will no longer be a humid / cold area.

 

[blup]

The crack looks to be in the mortar, so you might get away with packing it with cement, assuming no wood boring infestation.

Blup

 

[johnny2007]

Is there to stay for many years if you treat it.
But if you want a permanent solution, replace with concrete.
Easy enough.