HOW TO: Fix your leaky windshield

Joined
Mar 27, 2003
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Camas, WA USA
UPDATE: This fix is still working, it's bone dry 3+ years later.

I had water leaking into the cab from the windshield. It was a replacement windshield that was in the truck when I bought it. It didn't have the sealant/adhexsive as specified in the FSM. I noticed the carpet in the driver footwell was damp in the corner, and I would actually feel a drip on my foot from under the dash on occasion. Looking at the bottom interior corners of the windshield, I could see moisture, or a tiny puddle, in the corner where the windshield met the seal.

So, the water was leaking from the outside, migrating under the seal where the windshield met the seal, then going under the seal, under the windshield itself, and then coming out between the windshield and the seal on the interior. I have not found a leak from the sheetmetal side of the seal, even though it was not sealed either.

I tried to fix this two autumns ago, by using a "windshield silicone" that you can find with all the RTV tubes at the local autoparts store. This was a "flowable" silicone, that ought to flow into the leaky areas and seal it. I used this on the exterior along the seam where the windshield met the seal. I did not lift the seal and apply under the seal. This worked for a couple days, and overall reduced the volume of the leak, but was not successful.

Recently after posting up the windshield replacement PDF for another member, I decided to try to find the correct sealant and just apply the adhesive/sealant under the seal as noted in the FSM. I could not find the correct sealant in less than a case size online, so I looked for a Polyurethane adhesive locally. What I came up with was PL Polyurethane Roof and Flashing sealant in Black, from the paint supply area of Home Depot. It looked like it would do the job. You will also need cheap caulking gun.


First, I used a razor/scraper to try to get rid of the "flowable silicone" I had used before, then I used my finger to lift the seal and cleaned the seal and the windshield mating surfaces the best I could, using a dry cloth. When it was fairly clean, I used alcohol on a cloth. It actually felt like my seal may have been the original and had some adhesive residue on it from the original factory windshield. You can only get it so clean, so it would be better to have it done correctly with the install.

Next, I took some painters masking tape and put it on the winshield where it met the seal. I let it overlap the seal and then took a razor along the edge and peeled the tape off of the seal, this left me with a tape covering the edge of the windshield, to make it easier to keep the windshield clean.

After one last wipe of the seal/window mating surface with a clean cloth, I inserted the tip of the adhesive tube in the top center of the outside windshield/seal and started squeezing, I kept the tip"deep" and let the adhesive ooze out a bit, as I ran the adhesive around the windshield. I tried to make sure that there was a good mount of adhesive and no gaps. You can always cut/clean the extra adhesive, so be generous. When I finished, I gently pressed on the seal, just enough to make sure there was enough sealant to ooze out a bit, and make sure there were no areas where the seal was lifted up due to too much sealant.

It takes 7 days to fully cure, and you will smell it for about that long, it is strong at first, but not "deadly" as far as I can tell. After about 12 hours, I removed the tape, and did nothing else, but I did drive it with no issues. It will skin over after about 24 hours, and I think you would be OK in rain at that point, as it uses moisture to cure anyway, and I think the adhesive instructions makes mention of using it in wet locations.

I did this about a month ago, and it is bone dry inside. Hopefully, it will hold up in the long term, and I think it will. We have had some serious rain in the past month and it is always parked outside, so my expectations are high.

***Here is a link to my post with the FSM install document: Click here***
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Last edited:
Joined
Sep 21, 2009
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Covina, CA
Thanks for the write up Ben. I have the same problem in the same spot and also tried the flowable silicone without much success.

I just bought a new windshield gasket from CDan but may give this a try first.
 
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I had mine pulled out and a new gasket installed by a shop that knew what they were doing and glued both surfaces. No leaks since.
 
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How much did that cost?!? Mine has been dry for the first 2 yrs of ownership, then she started leaking... Now she leaks a lot. :mad:

Yours might be due to something being bent. Just sayin....:D
 
Joined
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If the rubber seal is not properly coated with adhesive on both sides (body and glass) and you wheel, eventually it will break loose. One day you'll be wheeling and crossed up and hear a popping sound from the w/s frame area and then you'll get this "something's rubbing behind the dash" sound the rest of the trip - especially on washboard. So, if you wheel be sure the w/s is properly installed.

DougM
 
Joined
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Camas, WA USA
I had mine pulled out and a new gasket installed by a shop that knew what they were doing and glued both surfaces. No leaks since.

That was my next step, but I saved about $100-120 by just sealing it myself. I am hopeful it will be a "permanent" solution, until the next time the windshield needs to be replaced.
 

CreeperSleeper

Cascade Cruisers
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Yours might be due to something being bent. Just sayin....:D

IDK what you mean... My 80 is pristine!:flipoff2:

If the rubber seal is not properly coated with adhesive on both sides (body and glass) and you wheel, eventually it will break loose. One day you'll be wheeling and crossed up and hear a popping sound from the w/s frame area and then you'll get this "something's rubbing behind the dash" sound the rest of the trip - especially on washboard. So, if you wheel be sure the w/s is properly installed.

DougM

I agree 100% :doh:
 

MDarius

I break stuff.
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Mine has started to rust bubble around the places it leaks. Unfortunately I didn't notice the leaks until I noticed the rust. Not quite sure where to take it from there.
 
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How much did that cost?!? Mine has been dry for the first 2 yrs of ownership, then she started leaking... Now she leaks a lot. :mad:

I got a new OEM gasket from Cdan, I believe it was about $30. The shop I used is in Humble, Tx. They charged me $125 to pull it, clean it up, and re-install it the right way. He used lots of glue. He used enough that he spent 15 minutes cleaning up the excess. It took him over an hourt to do it. I watched him do it and he did it right. When he cut the old gasket out, there was no glue at all on the glass part. I highly recommend the re-set option.
 
Joined
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I highly recommend resetting the windshield with a new seal for ~$150, as the best and most complete fix for a problem windshield leak. If you just want to fix your leaks for $10 and about an hour of work, then follow the original post. :D
 
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Just an update, I have been through tons of rain, as well as several weeks of freezing temps, still no leaks. I am very happy with my $10 investment.
 

MDarius

I break stuff.
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I'm curious as to how this will clean up when you need to get your windshield replaced.
 
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I'm curious as to how this will clean up when you need to get your windshield replaced.

I'm assuming it'll cleanup about as well as the urethane that should be there i.e. it'll be a pain but no more than usual.
 
Joined
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Camas, WA USA
I'm curious as to how this will clean up when you need to get your windshield replaced.

I just applied urethane to the glass/seal interface, so there will be nothing to cleanup when the windshield/seal is removed. Per FSM, there should also be sealant on the seal/sheet metal interface. So as mentioned above, if you apply any to that side of the seal, it will be about like it was from the factory as far as clean up is concerned.
 
Joined
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Shenandoah, PA
I just had my 2nd winshield replaced on my 1997 Landcruiser in a week. All under my insurance the first guy did not seal it up right and it leaked driver side dripping on the floor. I could see the rain running in the windshield seal. The second guy used plenty of silicone and No problems so far.
 
Joined
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I just had my 2nd winshield replaced on my 1997 Landcruiser in a week. All under my insurance the first guy did not seal it up right and it leaked driver side dripping on the floor. I could see the rain running in the windshield seal. The second guy used plenty of silicone and No problems so far.

Silicone or urethane? To note, the factory manual states urethane.
 

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