i have a 1978 olds cutlass supreme everytime it rains water comes in on the passenger side sometimes soaking the floor why is this happening the heater core was changed and so was the windshield

i would check the door, if I remember right the windows dont have a frame at the top. Probably just the seal, that is if my memory is correct.

just hose it down with water hose have a helper inside watching if none come in from top may be entering from bottom, does it leak when you drive or when parked?

if ya want to pay money just take it to a dealer, they can pressurize the cabin, tell ya where the leaks are.. I would just take hose to it tho, maybe use one of them attachments for fertilizer and fill it with dishsoap to make it easier to see, sounds funny but if you use a black light with some types they stand out

it leaks when its parked