85 D150 water leak (body)

I just bought this truck, has less than 100K miles, /6,727 (yes I know a 904 from a 727) and really pretty clean. Yellow numbers from factory still very visible on frame, solid cab, including floor pans, ONLY rust is over the rear wheel wells and even that is slight. Could use a pass. door not because of rust but it's beat up/ faster and easier to plop a door on than all the time it would take to straighten, dented and creased way up high.... PO could hardly see, it seems no garage door jam is wide enough for this guy..... the truck has definitely sat quite a bit over its 35 years. Outside, without moving an inch, for at least 3-4 years since I have known of the truck. PO said it had sat in a barn for 10+ years before he got it 4-5 years ago. (so he says)

anyways when I looked at it before I decided to buy it, the carpet was damp between the door and end of seat on driver side, below the dimmer switch. I didn't think much about it at the time because the door weatherstrips are shot.

well now that it's home, and I am digging into it to evaluate "just what I got myself into" it's rained and snowed a few times. I still have it on a trailer in the driveway, while I searched for an exhaust manifold for it. (the reason it has been sitting before I got it) well last weekend I noticed the driver side of the carpet was quite soaked. pass side isn't. I took the threshold off, and the screws holding the carpet down just forward of the seat edge.(surprisingly came right out, didn't break, weren't corroded at all...… and no, I don't think the old guy PO has ever touched them. all these screws are factory hardware.


so, in looking for the source of the leak, I noticed that with the carpet out of the way, a greenish stain (mossy color) at the floor pan/firewall/A pillar seam. I took out the E brake pedal and the cowl vent in the kick panel (this is a factory non AC truck) and it has rained and snowed some more, since. Hood has ~1-1/2" of partly melted, packed down heavy snow on it right now. Well today, I looked. Minimal wetness in that firewall to A pillar seam (on inside of the cab) but it was "wet". Nobody has been near this truck since the weekend when I pulled that Ebrake pedal and cowl vent panel. (it was in mid 50s and sunny last weekend) The wetness starts about 2/3 of the way up the firewall, just right on the original seam sealer.
Dry above that point.

I did notice that when I opened up the cowl vent on the passenger side, that it is full of pine needles in front of the heater core, that I can see. I've had older vehicles before, where the cowl would fill with leaves, etc I haven't had the wipers and cowl panel off this truck yet.

Now (finally) my questions... why would it be wet, "there"? and why would it start where it does? I don't believe this has been a problem for very long, there is no mold on the jute padding, the floor is extremely solid and in great shape, paint is intact (Ive seen wet cabs before, where the sheet metal goes bare when they have been wet, often)

With the shape the rest of this truck is in, I'm really hoping there is no terminal rust damage somewhere to cause this wetness..... who knows what about these cabs?

4 options:
1. leaking thru the seam sealer where the a pillar meets the roof, down the a pillar and out the seam just inside of the door switch
2. corner of the cowl where the cowl cracks. major seam there that never was sealed very well until the 88 up trucks and even then it cracked.
3. that vent you mentioned because the factory used open cell foam that degrades rapidly and doesnt seal against water.
4. firewall seam, which is magnified if the cowl cavern where the wiper assembly is is full of leaves.

I would remove the wipers and cowl grille. If its full of needles it can not drain properly. That is where I would start.

OK I'll check that this weekend and see if it is full of leaves.... can I blow from the vent area inside the truck with an air hose and "blow" it out once the cowl panel under the wipers is removed?
Its been a while since I've been in that part of a D/W truck.... I remember one of my F bodies (Aspen/volare) being REAL plugged up in this area when I got it years ago)

The cowl area drains at both sides, at the side of the firewall. The front fenders cover the drain holes. If it is full of leaves or pine needles, you will probably have to dig most of the stuff out of the box until you can get to both sides. then you can use a still wire to poke open the cowl drains (they are at the rear corners). Once opened, you can flush the cowl clean with a water hose, but if its really nasty, you may have to open the drains a few times before you get it clean. Gene

I have an 88 D100 that gets wet in the same place. Thanks to those who have BTDT! Now, thanks to the OP and all that responded, I know where to look!

thanks. hopefully that's all it is.... I've been looking for a nice, solid D/W truck for a long time.... other than this issue, this one fits the part... I actually have some "ideas" for the leaning tower of power.... if they don't pan out, there's a 440 and a couple of smallblocks sitting in the garage..... the "bigger" newer body style Furd trucks "eco boost" is 3.7L..... so is the slant 6 that is in this truck.... I think I can wake it up plenty, at least to the point of the stock HP of the mid 80s 360s, that "could have came" in my truck./

I had an 88 D100, by far was the WORST D series truck of all of them I had.... that TBI system SUCKED. 318, short bed, 2wd, got 8mpg all day long. worse than my 79 full time 4wd Ramcharger, worse than my 78 D300..... I put the most money into that one, yet had it the shortest length of time of them all....

'85 I bought years ago had the roof rusted out just behind the windshield. Not large holes (about 1/8th") but went almost side to side. Mainly bought it for parts so I didn't worry about it. Bought new in Georgia and here it's whole life.



Tim

With the kick panel vent off just stuff the shop vac hose in there to suck up the leaves. On the passenger side open the recirc door and try to do the same thing on that side and in front of the heater core. You'd really have to have a pile of mulch in there for it to hold enough water to leak in to the cab. The wiper linkage area under the cowl really doesn't hold much - it all washes down in to the vent areas.

The side vent windows leak on just about every one of these trucks. Runs down the door and puddles just below the dimmer switch. They do repop glass seals but often doesn't help with the leak. A drip coming down the fire wall is often a rust hole in the cowl under the wiper linkage. It's less than easy but ya need to get your head under the dash in a heavy rain and find the highest wet spot then poke around under the hood / cowl on the other side. A garden hose will also work.

It's a Dodge, it leaks. It might just be easier to put a drain hole in the floor. When I did my cab floors I used aluminum diamond plate instead of sheet metal.

My '79 had water exactly as you described. So far, it seems my fix was as simple as some missing grommets on the firewall, main one being the one for the speedometer cable. I still see a little bit of water dripping down from driver's vent window in a heavy rain, as RWG75 mentions, but usually not even enough to reach the floor now. Mine would get wet all around dimmer switch and puddle all down the floor near exit/entry. Not any more. Before sealing the firewall I did pull cowl cover and get a vacuum and my hands in as much as I could to clean out any leaves, etc. but still had the leak. I check weather report whenever possible, and when heavy rains are forecasted, I have a HD tarp from Walmart, and I cover the cab, and use bungie cords to hold it down. Good for protecting it from rusting out.

I've seen the wing window leaks on these trucks before, no evidence of that on this one. I haven't tried to open them up yet.
Wetness is way forward of that. And where the entry point appears to be, it's a ways away from the wipers and such. Like I said it starts in the very driver side corner of the firewall, way back in there. And drips down from there to puddle. Below the dimmer switch, and just inboard of the threshold.

In my post I was suggesting I DON'T believe it's your vent windows. You might get a little there, but I believe your firewall could be the issue.

You should take a good look at the area between the windshield and the roof from the outside.

This, up under the gasket specifically.

ok will do.... I mainly looked above the windshield, above the drip rail for rust bubbles when I looked the truck over before I bought it.... have seen lots of issues there..... never really looked next to/around windshield gasket.... honestly didn't think about looking there..... supposed to be mid 50s again Sunday, that will give the snow from a couple days ago a chance to melt off and dry, so I can see things better... I did open drivers door and look where it's normally wet yesterday, and it wasn't.... The other day when I folded the carpet back to the hump, it was "drip drying" as it wasn't touching floor pan any more, water from carpet pooled just on driver side of hump, that was even dried up..... been cold at night (teens) and just above freezing during the day.... would have expected to see a little ice in there from the carpet dripping off, especially in the floor pan "stiffener ribs" but no.

I have seen so many of these 1972 up truck cabs with a 3 inch long 1/8 inch wide crack in the firewall in the wiper linkage cowl area. I think its a weak area from the stamping that has rusted out. My son has this issue.

My 78 LRT has leaks at the windshield seam/gasket area and I think 1 wiper seal is leaking too. I have no floors anymore.

of what you have seen is this in a spot where I could easily get my MIG stinger in there and fix the issue? Just thinking ahead.
Ive heard of this before, cracks in the firewall area but have yet to see one.... (I haven't had this issue yet, must just have been lucky/ so far)
haven't had a chance to check out this area on my truck yet though either.
My floor pans are like new so here's hoping that this isn't my issue.
good info anyways because I don't plan on this one being my :last" D/W series truck...

what causes these cowl/firewall cracks? I wouldn't think it would be cab/body flex, as they are full frame. If they were a unibody vehicle that cause would be more understandable.

In the case of THIS truck, I wouldn't think that its /6 would have enough power to "hurt itself"-- relating to body and frame flex....

In the case of THIS truck, I wouldn't think that its /6 would have enough power to "hurt itself"-- relating to body and frame flex....

It's not just the engine that plays into it. It's the roads you drive, the loads you carry. That steep driveway you pull into at an angle without giving it a second thought, could be flexing things quite a bit (just saying as an example).

I've had a '76 and an '84 that had frame issues. The '76's issues were brought on by mileage, the '84's issues were possibly caused by a (very) minor accident the truck had been in early in its life. In both cases the frames had zero rust and neither truck ever carried something really heavy (especially the '84).

Yep! The TBI on mine sucks out loud also. It's just an old long bed, beater, firewood truck that rarely goes far from home. I've got a low mile 5.9 Magnum sitting in my garage with every piece of wiring from under the hood of its donor, including the computer and fuse box. As soon as I get time to sit down and figure out the wiring......the 318 TBI is going bye bye! I will save the roller block though!

I had a picture of this crack on my sons truck but can not find in on my hard drive.

The cab does get stressed a lot over the years. Mine when going over a un-even driveway the cab will make a 'BONG' noise when it flexes enough on the frame.

As far as getting a MIG stinger tip in there, I think you could from inside the cab. But I would have someone in the Cowl area holding a 'Copper' backer plate over the crack so you dont just blow through. I have a huge sheet of dead soft pure copper. I just cut a piece and hammer it into the shape I need and hold it under the hole or crack. Check out Mike Finnegan's "Eastwood' Hotrod TV vid on YouTube:

youtube.com/watch?v=huPdLOIA438

Getting into interesting topic. I've been wondering about boxing my frame, at least in spots. Now you have me wondering about the cab. I don't seem to have a leak in cab now, nor really a lot of flex, but thought it would be nice to make it more rigid. Maybe I shouldn't go off on tangent about boxing, etc. though.

Here's your youtube video Dave

https://www.youtube.com/watch?v=huPdLOIA438

yeah it is..... and getting farther reaching than I thought it would. As far as the copper bars, I have a few here, familiar with that trick.

I have an Eastwood store about an hour from me, saw that magnetic one there and thought of getting one while I was last there but the wife was made at me enuf for what I DID spend that day....

good suggestions, keep em coming.... and hopefully those pix of the problem area get "found" so we can all see them....

If you have any intentions of welding in the area of the bottom of the wiper box, I strongly suggest you pull everything out of the interior, the dash, the heater box, wiper parts, the plastic vent boxes, probably the wiring harness, and the carpet off the floor. You really need to get to a bare metal firewall. There is a lot of stuff in that area that will catch fire from the mig welder sparks that will be flying and some of the materials in the area will self feed a fire that may start. The entire seam along the bottom of the wiper box was filled (often very poorly) with a seam sealer from the factory. If you are welding in that area, the seam sealer really needs to be dug out. A fire starting to burn under a dash is in a difficult location to extinguish and would probably cause more damage the the water coming in would. Its not a quick weld job, I've done a few in the past.

While your checking stuff, it might be a really good idea to check the condition of the metal on the frame ear for the body mounts. The rubber mount will hold water and attract dust/dirt/sand and the grit of the dirt will wear away the metal under the mount. The result of that is there really is nothing keeping the cab on the frame, the metal will wear away to the size slightly smaller then the rubber mount. To check this, all you need to do is put a pry bar between the cab and the frame and see if you can pray the two apart. If its good, it shouldn't move, if its bad, the mount will pull right through the frame, any movement more the 1/8" is highly suspect. If your cab is making noises when the the body and frame flex, I would really check those cab mounts, all 4 on the cab, and the 2 at the radiator support.
That hasn't got anything to do with the water leak, other then someone mentioning body/frame flex. That Dodge truck frame and body were designed to flex, up to a point, its the extremes, or the deterioration of the original mounting system, that cause the problems. Gene

Yeah Gene I have seen that and repaired it before. I'm thinking my leak source will probably wind up being somewhere in the corner of the cowl where it wraps around and goes vertical, based on where I am seeing the seepage on the inside of the cab. If all checks out, I'd actually like to put a bird bath hood on to this rig meaning I'd be in that area because I will have to change the vented cowl panel under the wiper arms as those are different with the bird bath hood.
I thought I heard somewhere, that there is an area around that part of the cab that cracked too? I'm hoping that it doesn't wind up being anything to do with the windshield channel area.
Without pulling the windshield strip, what I can see there looks very solid so far.

Oh yeah I think someone mentioned wiper pivot area as a potential leak source? I thought that was just an a body issue?

TSB on cowl cracks:

http://dodgeram.info/tsb/1994/23-63-94.htm


More info:

https://ramchargercentral.com/body-interior/cowl-cracks/

exactly why my trucks have no carpet and spray on bed liner inside & out. also why I moved the dimmer switch to lower edge of dash by hood release. water would short out/rust the switch and it burnt up the fuseable link wires on 2 of my trucks. took a while but I found good replacement wire harness for the 85/88 trucks & moved the switch to high ground.
couple well placed 1/4' holes to drain floors well and it stays dry and a little damp in wet weather but dry's right up dry weather.

IMHO..they all leak no matter what. so drain it well and ride the wheels off before it rust away.

OH yea, windshield gaskets leak also. mine leaked and run water down the a-piller and then down between dash and kick panel to the floor.
cargo light leaked and run down inside cab and keeps seat belt wet and rotting in the bolt area.

Good idea Mike, move the dimmer to high ground, AND I agree, no carpet inside, bed liner inside (I think I'm going to do POR15) and a couple of well placed holes. I have nothing on the floor of mine now, and had posted a question about adhesive backed liners and my concern for moisture getting underneath. I'm eventually going to get a rubber floor and attach the insulation to the back of that so I can easily lift to feel for moisture.

Mike's right, drive the heck out of them after you do your best to protect!

Wow that TSB states "93-and prior"

Just how far prior I wonder?

'72

Okay thanks. Was thinking it might be an '81 to '93 thing.

The '72 to '93 is the same basic cab with a few minor changes.

I know, but was hoping there was some tweaking when the style changed in 81, and that way my '79 was safe from this possible problem.

I see more northern trucks with this issue than the southern ones. Probably has more to do with terrain.

Stealing the picture from that TSB, here is where my son's 74 cab is cracked (Red Arrows)

Its pretty flat around here, only "terrain" issues are bad local roads haha.... now road salt, and that brine crap that they love so much around here, I can see that making a difference, vs non salt belt areas.....

Thanks for posting that.....