I've not seen a case tapped like yours. Usually there is a brass T fitting in the side area. The T's generally aren't big enough to hold a temp sender. The oil pressure sender (black one) looks melted?? Same for the wire where the tape is. Could the oil pressure sender be blocking flow to temp sender? The wire from front to rear could be bad. Gauge might not be adequately grounded too. If you can get to wire on back of temp gauge - you could check it for open front to rear or run wire from sender to gauge outside the vehicle.
