How hard and what's involved. Got a mate who's has let go and want to see if it's a driveway job or not?

 

Very Very Rare to be heater matrix on the bmw e30 i bet it is the heater control valve leaking

easy to change mate done 3 myself

 

Apparently the glovebox was full of water could this still be the valve? If so how much and how do yu change it?

I can work my way round most Fords easy enough but have to admit to being a bit of a cretin when it comes to BMW's

 

Yes mate that will be the heater control valve it sits next to the glove box its a square box. black and white in colour

easy to change heater control valve new is about £80 pounds new but i have always replaced mine on my sport with second hand ones from scappy for about a fiver

if you go to e30zone.co.uk theres a step by step guide mate

good luck its a piece of piss