How can you tell if the rear windshield rubber seal is leaking?
 

I cannot confirm it but the wet trunk and the wet rear floors are beginning to irritate me.

Also, what is a fair price to have the rear seal replaced by a glass replacement company? thanks in advance.

I found that drips would be visible at the rears of the wheelwells - inside the trunk. The water would drip in from under the seal, and that is where gravity would take it.

I would not necessarily thing that a rear windshield seal would allow water into the rear floors, given how far back the bottom of the seal is. You sure they are not due to bad vapor barriers, door seals or sunroof seals?

A dripping front windshield seal would likely migrate in time to create a puddle in the back - but your front floor would be wet first.

Sure way to tell is to take a hose to it... If, after water has been applied, you feel wetness around the seal... bingo.

You'll probably need to find an independent glass shop to replace the seal for you. Most of the chains don't like cars with metal trim inserts in the seal.

great tip! i'll do the hose bit when the rain finally stops. it's funny how we sometimes forget to do the obvious stuff and jump into the most expensive repairs right away.

thanks again!

I'm widely known as a major smartarse.:D

I always felt up and around via the trunk to see if water was coming in. If the rain slows and the car is wet, that is a prime time to check.

But again, youll see drips in the trunk. may want to remove the c pillar trim and see if other water is coming in and down to the footwells in the rear.

I thought the wet rear floors were from leaking sunroof seals?

Leaks are a PITA to trace.

I have a slight rear window seal leak. I purchased some MB window sealant that I should be getting from the dealer this wednesday. I have yet to discover a leaky front windshield, but I am going to reseal with my caulking paste anyway.

are you talking about the rubber seal that goes around the sunroof? it looks old but seems fine with no gaps or anything.

is that easy to replace?

We had one, water sat on the outside glass, right where the rubber meets the glass, would seep under the glass and bubble up inside at the glass/seal contact point then drip down.

Put a tight bead of black silicone around the whole windshield...

great tip. thank you. i'll try everything cheap first. i assume this black silicone is a Home Depot item?

permatex type stuff from auto parts or HD type stores.

Can you kindly post the part number for that sealant. I need to pick some up and get the SD done.

I'm not sure the silicone is what you want in that location. It must be compatible with the rubber and the M/B sealant is probably a better choice.

Well it "bonded" to the glass and rubber well, and was very easy to work.

THe seals were going to be replaced within the month anyway, so it was a great stopgap solution, which is likely far easier to work than the MB sealant if the MB sealant is like normal windshield sealant and rubber in a solvent.

Right tool for the job, for sure, but if the OP is trying to diagnose, then the silicone may be a good shot. If it turns out that the windshield seal was faulty, it should be replaced regardless.