Causes of leaks only during heavy rain(Suzuki Lapin CBA-HE22S)

It is a consultation of the rain leak which is rare in a japanese car.

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Today, when I was about to start Lapin in the morning, I felt a few drops of splashes on my face that seemed to be coming from the vicinity of the indoor room lamp.
It seems that water entered the ceiling lining due to the influence of yesterday's rain.

There is a radio antenna of the exterior at the top of the indoor room lamp, waterproof performance (deterioration of packing, etc.?)we believe that this is due to a decline in the number of

Because it is a leak of water in the room, it is still better to repair it as soon as possible, right?

MY2009 CBA-HE22S F6A Turbo CVT Mileage 94,000km

I heard a web repair case that I applied a silicon-based liquid seal to the antenna base attached to the front of the roof and was cured, so I decided to check the condition and treat it first.

As far as visual confirmation, there was no place where there was a cut in the packing adhesion mark.An appropriate amount of silicon seal was applied to improve overall adhesion failure, and it was delivered through a simple shower test.

However, about a month later, a notice of a rain leak and recurrence came in.

Even at the time of the first leak, this time, because it was after a severe heavy rain, it seems that the identification of the leak site and the shower test were insufficient, and it caused a great trouble to the visitor.

I took care of it again, strengthened the momentum of the shower in the way of torrential rain, and tried to increase the injection time, but the dropping started slowly a few minutes after the start of the shower, and the momentum gradually increased gradually.And even if I stopped the shower, it was a strange phenomenon that the leak continued for a while.

When observed from the inside, water seems to be transmitting the bolt fixed at the center, not from the adhesion of the roof and the antenna base.Looking at the time difference of the leak, it seems that water has accumulated once in the antenna base, so I tried to order a new antenna base and look at the internal structure.

I thought that it was non-decomposed by adhesion, but it can be disassembled contrary to expectations.Corrosion was seen on the internal PCB (printed circuit board).

Because the white packing part is in a position higher than the roof, it seems that water was in the PCB room only when a large amount of rain fell.I also found out why the shower would continue to drip for a while.

Since there is no supply of parts individually originally, I think that adhesive sealing is good, but I hope that measures have been taken for the new antenna base.