Hello everyone, having a hard time detecting where water is coming into the trunk. All weather striping is in nice shape and as is the trunk lid. When I wash the car I will find water under the trunk mat. its set up for storage now, my next step would be to climb in the trunk , close it and watch for any leaks. All of the trunk floor pans have been replaced, thanks Jerry.

 

Yup, the next step is to lay in the trunk with a good flashlight while someone sprays water with a hose.

 

It could be coming in from the rear window not being sealed properly?

 

This ^

 

You say the weatherstrip "looks" good, but does it actually seal? The easy way to test this is to cut a bunch of 1" wide strips of newspaper, place them over the weatherstrip, and close the trunklid on them. If you can pull them out, the weatherstrip isn't sealing properly.

 

Thanks everyone for the replies, Didn't know about the newspaper test, thanks Joe. It was a little strange as the water would puddle under the mat. We will have to wait until spring to find out, again thanks.

 

Never use the rubber mat in trunk. It builds up moisture. Take it out in storage. Or wash the car then dry it out for storage.

 

THIS ^^^

If you have a heavy factory-style rubber mat and any kind of a humid climate, those puddles might just be from condensation.

 

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I have an after market rubber trunk mat in it, Didn't realize that it was the problem. Do you think this is one of the issues why so many trunk pans rusted out on 65's. Thanks.

 

Didn't say it was the problem, just that it might be. Take it out of there and see if things dry out.

As for heavy factory rubber mats being the cause of rusty trunk pans in '65s, all I can say is, they probably didn't help matters any. GM used this style of trunk mat for many years over many models.

 

The problem was the rear window leaking then the water trapped by the rubber mat rusted out the floor.

 

Check the seals around the taillights.

Best way to find the leak is to climb in the trunk with a flashlight. Have a helper spray the car down with a hose, look for the water leaking in.

 

I had a 65 Sport Coupe 442 that had the same problem. Found out the trunk lip was bent down too deep to let the seal keep out water. A little hammer and dolly work fixed the problem.