When I bring my car to automatic car wash, my trunk is wet. When I wash it manually, my trunk stays dry. The weatherstrip in my trunk is broken, please look at the picture attached.


Is there a way to fix it, instead of replacing the whole long trunk weatherstrip? If I really have to replace it, can I take out a used one at a salvage yard?

 

From the picture it does not look like that gash would cause the trunk to leak. The top of the rubber is intact, and that would still press against the trunk lid forming a seal.

My bet is that some of the adhesive holding the bottom of that strip in place may be old, leaving gaps underneath where the water can enter. If that is the problem then order a tube of this (or equivalent)


and glue those sections down again.


Have you priced a replacement OEM strip? It is just a piece of rubber and should not cost all that much. Generic replacement weatherstripping is not expensive:

https://www.ebay.com/i/390978142038?chn=ps

If you get one from the junkyard the rubber will likely be as old as the car so it might not last that long.

 

I checked with my finger and eyes the bottom of the strip and I didn't see any gap. If I buy the generic replacement weatherstrip, can I cut only a small part to replace only the part around the gash and glue it?

 

Try squirting some water along the lower edge while wiggling the weatherstrip back and forth and see if anything gets through. If not then the glue is most likely not the problem.

Normally one replaces an entire piece of weatherstrip to avoid junctions, which are prone to failure if the glue lets go. However, in this case, if the generic is a bit longer than the total amount you would need, I don't see any harm in cutting off a few inches from one end and trying the patch. Worst case, it still leaks, and you replace the entire length later.