Started fixing cab leaks
 

Pulled passenger side fender today NO cab cracks at all after 1.1 million miles. I sealed a little rubber trap door on front of cowl and put new seam sealer along firewall seam. Will water test it tomorrow before reassembly and then tear drivers side apart which was leaking much worse than passenger side.

Im also using POR15 to paint any light rust spots. If u ever use this stuff, definately use rubber gloves as it doesnt wash off skin much at all.

That is great to hear. What year is your truck and are you the original owner?
I have often wondered if the shudder the Cummins powered trucks make when they are shut down contributes to the cowl cracks, especially if you shut it down with the door(s) open, since I rarely see the cracks on gas powered trucks of the same vintage.

I think it's probably more prevalent in the 4X4 models because they go out rock climbing.

I had cowl cracks on both my 2wd gas power Ramchargers that both had under 100,000 miles on them.
Both my crew cabs, that are now 12V powered, had them too before doing the swap.

I find those cracks on most any 1st gen I work on.

I must be the only one who doesnt have cowl cracks. Pulled the fenders off 2 years ago and was quite surprised, especially since my front cab supports are rotted.

its a 1993 4x4. I pulled the drivers side fender today, which is the side that leaked quite a bit. NO CAB CRACKS. It appears water is coming through the floor vent kick panel. why it hasnt done this years ago is a mystery. but it seems like the water tension pulls it over the lip of the vent and then it dribbles down to the lower parts and leaks into the cab. So.

Any ideas on a solution to remedy this and keep the floor vent working?

Check for leaves etc... in the vent. I know that stuff gets in the other side and fills up the heater box in front of the A/C evaporator.

https://cimg6.ibsrv.net/gimg/www.die...325f569013.jpg
I use adhesive backed foam tape to replace the deteriorating OEM foam gasket on (3) of my trucks to stop the leaking.

Heres a couple of pics. Wouldnt it smart if the rain gutter above the plastic scoop went all the way across so water didnt pour on the scoop?
https://cimg3.ibsrv.net/gimg/www.die...556d337525.jpg
https://cimg3.ibsrv.net/gimg/www.die...934833dfb4.jpg

NO MORE LEAKS!!! I did a couple things. 1-resealed floor vent with new foam. 2- added a ring to the floor vent inlet to stop any water that leaks inside scoop 3- put a splash shield above the inlet to stop cowl water from dropping on inlet vent. Here are pics and a youtube link I did.
​https://m.youtube.com/watch?v=MKjx9sxWSbg​​​​​​
https://cimg5.ibsrv.net/gimg/www.die...3ef38521f0.jpg
https://cimg6.ibsrv.net/gimg/www.die...318fd040d3.jpg