Hey guys my mate wanted me to ask you guys a question about his XH. He says everytime he washes it he gets a heap of water inside the cabin and also he cant start it for the next 12 hours. Just doesnt turn over, click or anything.
Cheers

I would say the plenum is rusted out (the area between the windscreen and bonnet)
It is pretty common on x series falsons. Take passenger side wiper arm and plenum grill off and have a look

Is he cleaning the engine every wash? If not I would say the ecu is probably getting moisture in it and needs a day to dry. also caused by leaking plenum.

Ben