Windshield Water Leak?

[brown7373]

We had a very heavy rain the other day, and my truck was parked outside. When I got in it, I had some water on the floor. When I drove away, it started pouring from under the dash, right under the A/C controller and under the lighter. It increased when I accelerated or turned corners. I think it is coming mostly from the passenger side. I used to get a leak on that side and it would soak things in the glove box. My windshield has a new rubber molding with the stainless trim inserted. When that was replaced, we checked around the edges and it all looked sound.

Anyone had water leak around a new windshield seal (gasket) before? I don't think that rubber seal is supposed to get any cement, is it?

[n33k0]

My '72 has a similar leak. I noticed a small pool of water forming where the dash meets the bottom of the windshield, and there is a small hole in the metal beneath the windshield rubber that lets the water drip behind the dash panel. The windshield was replaced a couple years ago by the P.O. so I'm not sure if that rubber counts as "new" (it's certainly not 42 years old! )



I am planning to poke around behind the grill that sits beneath the windshield wipers, I've read that area is prone to clogging and rusting out leading to leaks inside the cab. Not enough daylight to get all my projects done!

[BLT gmc]

Yes, the windshield and gasket are good places to start. I would also inspect the plenum from the air induction and the cowl area very close. These areas are prone to rot and let water in the cab when the truck is just setting there. Good luck, Bruce

[70shortfleet]

Dry everything off, get inside and have someone squirt water with hose and see if you can find the leak!

[Andy4639]

Top of windsheild corners just about aways leak. Put a little sealer in them and be done with it.

[brown7373]

I think I will try some sealer in the upper corners and maybe the bottom corners. I have sandalwood carpet, that now has a huge discolored spot!

[BruthaMan]

Another place to check is the wiper motor seal. There is a seal that goes on the outside of the cab, where the wiper motor comes through the cab. If that seal is missing, cracked or gone, it will leak in, run down the left side and poll on the passenger side floor. Replaced mine a few months back and solved that issue, but I also have windshield leak at both top corners too.

[Sklptrljay]

I had the upper corners of the windshield leak on my old truck, and on my current truck I had a leak from the grommet for the antenna.

[GuyO]

My antenna grommet leaked badly and next to it (under the valence) the factory used some putty at the joint below the windshield that cracked. The crack was about 2" long and about 1/8" wide. Be sure to check that area as well.

[JimKshortstep4x4]

Top corners as has been mentioned are prone to leak. In the service manual, instructions for installing windshields, after installation, state that sealant is to be applied at both top corners. A 6" bead is to be applied in both directions from each corner.

I have seen lots of original windshields that don't have the sealant in the corners and they leaked!

Jim

[dsy1]

I have a leak also, which gets the inside of my glovebox very wet. I assume this rules out the wiper motor and A/C-heater box, since those would be too low. What else could could let in enough water to pool in the glove box liner?

[Sklptrljay]

Originally Posted by dsy1

I have a leak also, which gets the inside of my glovebox very wet. I assume this rules out the wiper motor and A/C-heater box, since those would be too low. What else could could let in enough water to pool in the glove box liner?

The windshield upper corners will allow water to carry into the dash and glove box. Ask me how I know

[brown7373]

My glove box gets soaked too. Any recommendations on what sealer to use? I have seen 3M windshield sealer. Doesn't the antenna grommet just allow water into the cowl, same as the slots by the WW wipers? Speaking of WW wipers, what was Chevy thinking by putting the wiper motor & washer on the INSIDE, under the dash? Talk about a real pain to get to.

[sboris]

The antenna lead coming in at the base of the windshield on pass side often gets overlooked. Stand on your head with a good light to see that one.
Windshield is probably it, new gaskets don't always fit as well as oem, could require resetting, or maybe a little sealer.
Definitely check that wiper motor as mentioned, thats a BIG hole there..
Looks like you you have a very nice truck, but can we rule out RUST? Couple areas to look for. Again, around the wiper motor, and there is what I call a vertical seam on the drive side, above the fuse panel, and on far pass side that is just under the cowl. Those seems can get moisture Inbetween them and rust. Ask how I know..
The only other areas I can think of are on the firewall and shouldn't be affected by rain...
Hope it's something easy, good luck

[brown7373]

I didn't consider where the antenna wire comes through at the windshield base. And I will seal the corners and check the WW wiper. I need to replace the washer pump anyway...again

[BLT gmc]

I have resorted to a garden hose to help recreate the leak. This helps if you can not se an obvious source.

[Sklptrljay]

Originally Posted by brown7373

I didn't consider where the antenna wire comes through at the windshield base. And I will seal the corners and check the WW wiper. I need to replace the washer pump anyway...again

When I said earlier that it leaked through the antenna grommet I should have specified. It leaked from the hole in the dash not the exterior hole on the cowl. To find the leak, I had my daughter look behind the dash while I sprayed the windshield with a garden hose. I couldn't even see a hole for the antenna there, but I guess 9 year old eyes can see just about anything.

[808turbo]

What kind of sealant do you use. When I removed my winshield it a white putty in the croners. It looked like plumbers putty.

[brown7373]

I am not sure what sealer to use either.

[Duelly]

Hi, I am new at this site and I have a 1970 CST/10 and only had this truck since last September. We went on a road trip with our truck club I belong to and it had been raining on and off during the day and on our way home at 8:00 I lost all my tail lights and marker lights. One of our members followed me all the way home. It had blew 2 fuses and the fuse box was damp and some rust on the connectors where the fuse connects into. Its been in storage all winter with no electric in the building where it is stored. The ice and snow was halfway up the front of the door. Just two days ago I got the door opened to begain to work on it. but, where do I start? Not sure where the water would be coming in from. Its totally dry now. Where should I start looking for the problem. Hope someone has an answer !!

[R.L.]

Buy a sealant made for automotive applications, RTV silicone will eat the metal around windows. I used this stuff on a Nova and had to have some body work done.

[LockDoc]

Originally Posted by Duelly

Hi, I am new at this site and I have a 1970 CST/10 and only had this truck since last September. We went on a road trip with our truck club I belong to and it had been raining on and off during the day and on our way home at 8:00 I lost all my tail lights and marker lights. One of our members followed me all the way home. It had blew 2 fuses and the fuse box was damp and some rust on the connectors where the fuse connects into. Its been in storage all winter with no electric in the building where it is stored. The ice and snow was halfway up the front of the door. Just two days ago I got the door opened to begain to work on it. but, where do I start? Not sure where the water would be coming in from. Its totally dry now. Where should I start looking for the problem. Hope someone has an answer !!

Check the inside of the drip rails for any cracking/chipping of the sealant and seal as needed. Also seal along the top edge of the windshield gasket, especially the top corners. It is probably getting into the cab from the body seams at the bottom corners of the windshield. Below is a picture of the problem areas on my '67 Panel that I had to fix. If you take care of the drip rail and windshield gasket areas it should keep the water from getting in until you can do a more permanent repair.

As far as the fuse box, I use a Dremel type tool with a small round stone in it to clean the fuse holders. You can also replace it with one that isn't rusty (means changing the under dash loom) or completely disassemble it and clean the contacts up.

LockDoc

Originally Posted by R.L.

Buy a sealant made for automotive applications, RTV silicone will eat the metal around windows. I used this stuff on a Nova and had to have some body work done.

I don't think it is the silicone itself that causes deterioration of the metal but it attracts moisture which causes it.

LockDoc

[57taskforce]

Leon, with the windshield in place you probably never knew those holes were there did you?

[Possmguts]

That comes from this....

[michael bustamante]

it sounds like now is a good time to make sure my cowl area and windshield lip are in good shape and freel of possable waterleakage while the glass and front clip is off