Windshield Hinges - How to Caulk?

[numby]

I've moved to a soggy, rain drenched part of the country and have discovered a wonderful leak in the cab of my 40. Basically I get a fairly continuos drip just behind the A pillar when it rains. When i get underneath the dash with a flashlight I can't seem to trace it. I can feel the wire from the interior light where it passes through the windshield frame and cowl and it's always dry so that's not it. The water seems to be collecting on top of the seam/ledge between the cowl and the kick vent panel and then drips down various wiring, etc. Here's what i've done...

I replaced the hood hinge gaskets but I still had a leak (but not into the engine bay) The door seals are good - no leaks there. The door hinge seals are good and I even caulked around them and then repainted the area to make certain that they weren't a source of leakage behind the A pillar. I caulked the windshield hinge bolt holes with silicone and still it leaked. I removed the hard top and replaced the cowl to WS frame seal as well as the upper WS seal (no evidence of water ever having gotten in either of those ways), re-assembled and I've still got a leak. I've got a complete set of all the little windshield to door bow seals somewhere but I can't find anything after my move so I used liberal amounts of strip caulking instead. All seems good in those locations.

So then I removed the hinges again to check the alignment thinking that the windshield wasn't seated close enough to the cowl for the new seal to work but everything lines up perfectly (including fiberglass hard top and door bows). I taped off the bolt holes and squirted a fair amount of water at the cowl seal from every direction and no leak. Removing the tape from over the hinge bolt holes and squirting some water at them effectively re-created the symptoms albeit to a lesser degree. So it's gotta be the bolt holes - right?

I've scrayped off the old sealer, sanded and re-painted the hinges and the WS frame, and am about to assemble again. So what do I use? RTV? Silicone tub caulk? Little chunks of strip caulk. Chewing gum?

 

[dgangle]

water leaks can be difficult to locate.

My suggestion is to get everything back together, sealed, etc and on a dry day with a helper, a good flashlight and a mirror, get inside your truck and look at every crack and crevice while your helper douses the exterior with a garden hose.

Thre are only so many places it could be coming from. For me, historically it has been the WS fame to tub seal that gives the most problems.

It ain't magic. You are smarter than a leak and can find/fix it.

 

[numby]

Thanks for the vote of confidence. Are there ever any dry days in Oregon?

Have you ever seen a new WS to frame seal leak? Removing my old one didn't reveal any evidence of dried water/dirt/debris having puddles on the tub but I replaced it anyway.

Looking at my hinges I''ve noticed that, though the holes seem to line up with those on the WS frame and cowl, the upper and lower portions of the hinge are not parallel. There's a slight difference in the angle of the two halves which makes me think that the WS is slightly folded back at the top. The hard top fits without much effort so I assumed everything was lined up. Should the hinge parts be perfectly in line? I don't think I could use one of the one-piece mount plates that Spectre sells as nothing lines up that well.

 

[dgangle]

Water leaks can come from anywhere and what's funny about water is that it can travel, showing up away from the ultimate source. You just gotta dig in there cause no one else is going to do it for you.


I had a leak in the drywal ceiling of one a second-floor bedroom. Long story short, it was leaking around a single nail on the furnace vent and running down the stack to a horizontal metal support, across the support and then down a joist then hitting an AC duct in contact with it then running down around the ceiling HVAC vent soaking the insulation. Lots a time in the attic at night with a flashlight while it rained on that one. A dab of silicone on the head of one nail and prob solved.

Post pix of the hinge gasket you mention. Anything is possible but don't get too narrowly focused. Look at all posibilities and keep in mind my little story.

 

[sepr2]

If the windshield hinges are not in line (Angled back I would guess) the gasket under the windshield may be compressed from age and the cause. The hardtop when installed would push it forward some and may cause a leak. Maybe?

 

[numby]

Water leaks can come from anywhere and what's funny about water is that it can travel, showing up away from the ultimate source. You just gotta dig in there cause no one else is going to do it for you.

I hear you. As long as there's even the slightest slope water will use it even if it has to fill up a low spot to then overflow and continue downhill.

Post pix of the hinge gasket you mention. Anything is possible but don't get too narrowly focused. Look at all posibilities and keep in mind my little story.

I'll keep looking. I have the fear that it's all related to my half-assed caulking of the bolt holes which you can see the remnants of in the pic. I keep thinking that the entire windshield frame is filling with water and flowing into the dash from the drain holes. And then the flying monkeys take my legs and throw them over there...

If the windshield hinges are not in line (Angled back I would guess) the gasket under the windshield may be compressed from age and the cause. The hardtop when installed would push it forward some and may cause a leak. Maybe?

That makes perfect sense but the gasket under the windshield is new. I didn't exactly remove the hard top but instead removed all the bolts holding the fiberglass cap in place except the lower ones in the gussets across the ambulance door opening. This allowed me to tip the cap up in front while it pivoted on those two rear bolts. After I replaced the WS gasket and swung the windshield back up into place, the cap sat right back down in the original position. everything went back together fairly easy. I mean, it was tighter, but not that much.

I taped off the bolt holes and sprayed a ton of water at the gasket and didn't get any leaking but it just doesn't look right to me. You can see that the WS frame sticks out at the bottom and, even if it didn't, it's still not sitting at the same angle as the body. I tried pushing on it with brute force but it doesn't wanna budge. If the gasket is squished in back and has incorrect or reduced pressure in front I'll get a leak eventually as it ages/shrinks.

I'm going to get a few bolts and washers tomorrow to see if I can clamp the windshield into the proper position via the hinge. I'll keep looking for other possible leak sources as well.

 

[handcannon]

Are there ever any dry days in Oregon?

.

Yes, but you have to wait until about the first week of August then don't blink or you won't see it. JK Welcome to the great Pacific NorthWET. Which part of Oregon are you in?

Don

 

[dgangle]

pic looks OK to me. Bolt everything together, remove your dashpad and defroster top plastic pieces and douse with water. This will let you see if the water is getting inside the windshield frame. I doubt it, but anything's possible. I bet it's leaking at the gasket between the tub and WS frame....at least that's where mine have usually leaked.

 

[sepr2]

I have heard a lot of the aftermarket replacement gaskets are thinner than the original OEM one that goes under the WS frame to tub...

 

[numby]

I have heard a lot of the aftermarket replacement gaskets are thinner than the original OEM one that goes under the WS frame to tub...

WS weatherstrip is new OEM. I made certain that the included strip caulk provided good coverage.

I got a call to look at a muscle car clone for a friend out of state so I didn't get back to my leak until late last night. I still hadn't bolted the hinge back on so I decided spray a little more water at the gasket. I did notice a slight amount of water getting just behind the (lower) leading edge of the windshield frame. Maybe that's due to the the slight offset. Searching under the dash for an hour revealed no drips or wet tracks or dampness. I was about to go in and watch a movie when I noticed there was water puddled on top of the ledges formed by the cowl panels just behind the A pillar (inside) again. Both sides nonetheless. WTF?! There's got to be a trail of water from somewhere. A drip. A wet wire. Something. I look again. Nada-zip-nothing. Screw it. I'm going in for the night.

As I was sopping up the garage floor I notice how the water dripping from the cowl onto the running board was following the cowl seam. So I grabbed a mechanic's pick and started idly poking at the seam. Hmmm. There's a barely discernible hairline crack in the paint covering the seam. Well, I think, the PO sealed the seams before he painted so maybe the paint or the sealer shrunk a bit. Another idle poke and VOILOA! A chip of paint flakes off followed by a piece of FRICKEN BONDO!!!. And now there's a visible hole at the juncture of the cowl/firewall/kick panels big enough to jam the pick all the way in. Squirt squirt squirt. Water is spilling off the ledge and onto the floor. Going to the passenger side. Yep, there's a hairline crack in the paint. More squirting. Water puddles on the passenger floor. A poke with the tool and a half inch long piece of bondo pops out. Apparently water is wicking through the cracks in the paint. This may not be the end of my leak issues, but it's a start.

I curse the PO's dead grandmother and go to bed. I'll deal with this tomorrow.

 

[numby]

Final Follow-Up ( I hope)

While addressing the bondo seam sealer issue I outlined above I discovered that there were tiny hairline cracks running along the length of the cowl seam. Apparently the sealant had shrunk slightly through the last dozen or so years since the vehicle was painted. Though the seam appeared OK, closer inspection revealed that telltale rust-colored tinge at each little crack that evidences water having gained access to metal. The sealant looked to be 3M's "Fast-n-Firm" stuff. It was brittle, cracked, and was no longer adhering very well to either metal or paint.

So I dug it all out, sanded, sprayed with a rust converter, primed with Eastwood's Corroless, caulked with polyurethane (Sikaflex, Tiger Seal), primed again, sanded again, and rattle canned the hell out of the cowl. I let it all dry and backed the 40 out into rain overnight. Checked it this morning and not a drop of water on the floor or under the mats. I didn't even get around to re-caulking the windshield hinges. Went on a nice 50 mile drive through the countryside on an errand this afternoon in the rain. Still not a drop inside the vehicle. Man, it's nice to be dry again.

Thanks to those Mudders who offered support and special thanks to dgangle for diffusing my frustration with his encouragement. I guess I am smarter than a drip. from the Willamette valley!

 

[John McVicker]

Good work Numby. Would it be possible for you to post pics of your recent repair ? I am thinking of removing some old brittle 3M caulking myself but am worried what the finished work will look like.

I have no leaks since I caulked the WS, hinge holes etc. w/3M approx 10 yrs. ago but it is now looking prety bad as the caulking has dried & aged. Sounds like you did a whole bunch of work. Long, hard tedious work. I will probablly use your game plan & would love to see some pics.

Congrats on your success.

John

 

[acollins10]

Glad to hear to fixed the problem. What part of the W Valley are you in?

 

[AATLAS1X]

See my 1981 restoration thread, you will see the caulking behind the hinges like factory and addressing water leaks.

Shane

 

[numby]

Because of the mood I was in when I realized that the entire cowl seam was toast I didn't document anything well enough for a true write-up. I just jumped in and started digging. Below are pics of the right and left side of the cowl seam. Note: I did not do any of the original body work on this vehicle. I bought it with a fairly decent paint job (my first mistake) and do little to maintain it beyond hosing the mud off. Even then I mostly focus on the undercarriage.

Below are pics of the cowl seam before I started showing the faint crack in the seam paint. The close-up of the section below the wiper motor cover reveals the telltale rust color. This is one of a half dozen sections where water was wicking through into the cab. Kind of hard to believe at first but, once I chipped a little paint away you could see quite a bit more space between the hardened caulking and the metal panels.

 

[numby]

Here are the steps I followed:

1) Using a utility knife I scored the paint on either side of the caulking to minimize chipping and give myself a more easily sandable transition point. Alas, I failed to cut deeply enough and still ended up with a snaggle-toothed edge. Tip - Cut deep enough to reach metal.

2) Using my favorite rusty seam restoration tools - a linoleum knife and the aforementioned utility knife - I began removing the old paint and caulking. (See pics below) The panels are spotwelded together and I actually got the linoleum knife in deep enough to get stuck and snapped a small portion of the blade off! I have used this tool to scrape heartily between frame "C" sections without incident in the past. Apparently I was freaking determined this time. Notice the rusty tint to the revealed metal where sealant/paint used to be.

3) Once all the old caulking and paint was out of the seam area I followed up with a few different grits of sandpaper. I used (I think) 150 to eliminate any rust colored patina that had begun to develop on the metal in the seam itself and 300 to smooth the transition point between bare metal and the edge of the old paint. Vacuum out the dust and wipe with de-natured alcohol.

4) Using Eastwood's Rust Converter I doused the seam area. Bare metal is unaffected but any remnant of rust turns black after it dries. About a day or so. I always follow up with a blow drier in Oregon's humid climate before beginning the next application of paint/primer/etc.

5) I applied an even brush-on coat of another Eastwood product called Corroless. I think it's now called "Rust Encapsulator". I use it in the red color so that I can easily monitor coverage. It was supposedly developed for painting oil rigs and, when dry, is damned near impervious to anything, When I got lazy while draining my gas tank recently and pulled the drain plug rather than siphoning, all the paint in the gas tank well got soaked with unleaded and dissolved away. But not the Corroless that I had used for a few touch-ups when I replaced the tank pads a few years back. I think it's almost as tough as Hammerite or maybe even POR-15. See my photoshopped pic of the original seam to see an approximation of what this step looked like. Note: Corroless is a very dark red. Kind of like the Golden Gate bridge. The image is light to more clearly see the contours of the cowl area.


6) At this point I applied the polyurethane caulking. I have used the firmer setting two-part caulking that AATLAS1X advocates and it is a tremendous step up from the typical products out there. But, after talking with a number of body/paint places, I came away with the sense of a trend toward PU. It remains flexible for darn near ever, is paintable, and can be applied underwater!. It flows too easily to duplicate the original caulking used by Toyota which stood proud but I wasn't aimed in that direction. I just squeezed a few fine beads of the stuff into the seam area and, using a 3" square piece of plastic cut from a milk carton with one corner radiused slightly (approximately 1/4" radius) I squeezed the caulking into the seam. With one final pass completely across the cowl I was left with a very nice cove shaped bead. Using reducer (or lacquer thinner) quickly remove any excess caulking.

7) After multiple sandings with progressively finer grits to get a respectable transition between the Corroless and the old paint I masked off the windshield and hood hinges (yeah, cheezy, I know but there was caulking under the hood hinges from my previous misguided attempts at stopping the leaks) and gave the cowl a quick blast of gray primer. A little more sanding with 2000 grit to smooth the primer without revealing the dark red paint underneath, a little more clean-up with alcohol, a good warm up of the cowl area with the blow drier, and out came the rattle can of Dune Beige. Note: I did not sand the actual sealant as I wasn't certain how it would react.

I think the result is acceptable considering that I was not working in an appropriate sterile environment. Just an unheated garage with a temperature somewhat below those recommended by the manufacturers of the products I used. There are a few dust motes in the final coat of paint and I'm not going to wet sand at this time. It looks good from a few feet away and will not present problems if I ever come up with the scratch to repaint back to original. Yeah, it's redneck. What of it?

 

[John McVicker]

Excellent work Numby. And not at all redneck. Redneck is my 10 yr. old repair. Yours looks really great. I've saved this thread for my attempt in the future.

Congrats again. John

 

[numby]

It's only fair...

...that I show the result. The pics below are from this morning.

Not perfect by a long shot. A few runs and sags. You can see some of the deeper scratches caused by my careless haste and disinterest in using filler or spending the time on perfect sanding. Still, I don't think the seam will leak for a good long while. Yes, that is saran wrap under the windshield hinge and some temporary bolts instead of the gold factory ones. I still have to caulk under them. The gray primer overspray on the wiper arm is from when I recaulked the rain gutter. Don't ask me how that happened. To paint the cowl I masked the hinges (hood & WS), the new WS weatherstrip, the kick vent panels at the horizontal seam, the hood, and the A pillar joint. Start at one side and work progressively across the cowl with the spray can. Keep a wet edge and it comes out fairly decent.

There are three or four polyurethane caulks on the market that I know of and probably more. Sikaflex, Tiger Seal (which I used), a two-part version which I don't remember the name of (and requires a fancy gun), and a 3M version that comes in a soft tube but also requires a special gun. My impression is that typical seam sealers are only good for ten years or so. Too much shrinkage and hardening. PU is not supposed to suffer that kind of degradation. Time will tell.