Hello I have posted a thread before about how I got water in the cab when it rains everybody said clean the cowl drains out I did that and it still leaked I flex sealed the entire seam where the putty is and it still leaks when I put the water hose on top of the cowl. It look like it is going in the square hole that is towards the engine on the passenger side athlete the truck is warmed up and I run the water hose on it the water that leaks in is warm it not antifreeze how can I fix this issue. Thanks

 

I saw your other topic and I suspected the Cowl Seal. I was surprised that no one mentioned that!

It's a seam that goes all the way across the cowl, inside, underneath the windshield wiper arms assembly - accessed by removing the cowl cover (which is the the body part that the windshield wiper posts come through and has the vent holes).

You have to remove the wiper arms from the posts to take the cowl cover off and there are some precautions and tips that you should be aware of before you start this job.

It's a long seam in the bottom that was sealed at the factory with a self levelling elastomeric sealant that eventually gets old, dried out, loses it's elasticity and adhesion properties and then LEAKS.

I can show you more about it later. I was planning on posting the whole job in the "What did you do to your IDI Today" topic but haven't got around to doing that yet.

I do not have time right now or tonight to even discuss this subject so just search the forums for "Cowl Seal" and see what you can find. It is NOT the 'Hood to Cowl Seal' which is a long rubber seal near the top of the firewall which seals the gap between the back of the hood and the cowl to prevent water from running down onto the back of the engine and the air cleaner<- which can cause a serious problem if water gets through the intake.
That is an unrelated but very important thing to also check in these old trucks.

 

I have cut the old seam out and siliconed it and let it dry and then flex sealed it

 

Open the hood and follow the hood to cowl seal to the passenger side where it ends before the hood hinge. The water collected by that seal drains off the ends and on the passenger side it flows right onto the top of the heater and A/C housing (whatever it's called) The heater blower motor is bolted to the front of it. There is a vaccum valve on top in the corner that controls the fresh air intake door inside of it. Check all along the top and sides of the box to find anywhere that water could be getting in.

If you spray a good amount of water over the gap between the hood and the cowl before opening the hood you'll see where the water goes after you open the hood.

That's another area I would have suggested to rule out in you first topic but you had indicated that it was already fixed.

Good Luck! I have to run out of town for awhile and work on other stuff tonight

 

Pretty sure that not it it is under the cowl somewhere because when I put water directly in the area under the cowl is when it leaks and water is not getting on the blower motor at all

 

Fixnstuff in post# 2 explained it pretty well.


In the following thread, scroll down in post# 1 to the 20th picture, and the next 5 or so. Some good pictures as to what is under the cowl vent area.
it is an Air Box where the air comes into the heater and vents etc.
This is where I believe you water leak is.


https://www.ford-trucks.com/forums/1...b-project.html




Where the Heater Hoses connect under the heater box in the engine compartment, I believe water could leak in.
I use to here my Dad mention Body Dum Dum (I believe is was) or Monkey Sh... er.. stuff that was originally pushed in
areas from the factory to plug up holes around hoses etc...
Kind of like a sticky play doe.


I have some water leaks under the Dash on drivers/pass sides. I believe my problem is in this Air Box area.
Also leaks in the corners of the Windshield and across the top of the Windshield that drip. You could have leaks in this area also.




Charlie

 

I cut the old seam sealer out siliconed it then let the silicone dry and then flex sealed the whole cowl area never saw a spot of rust

 

Hi, my old '86 leaked right in passenger side floor. It was a leak in the heater core.

 

That ended up happening at one point on my '88.
Made for some nicely fogged windows in the morning, and the coolant smell at that point got bad.
Replaced the heater core, problem solved!

 

Butyl rubber tape, they sell it at parts stores, resealed my air box to the firewall, no more leak.

 

can you post a picture of "the square hole"?

 

I'm sure tjc transport knows this so:

To the original poster: Under the cowl cover on the passenger side, approximately in line with the passenger side hood hinge, there are at least two holes, a larger trapezoidal shaped one about 4 to 5 inches long as I recall and 2-1/2 to 3 inches wide.

It's called a Cowl Access hole and it is supposed to have a rubber plug or cap, shown on this page from the LMC Truck Catalogue, Number 7 in the drawing. Also see Numbers 8 and 9:
Truck Parts and Truck Accessories

The edge of that rubber plug or cap, as I recall it has a grove in the side of it it, all the way around where the metal edge of the hole fits into the grove and secures the plug. When it gets OLD the rubber loses it's elasticity and flexibility (as is very common with rubber parts after nearly 30 years of exposure to the environment). It tends to dry out, shrink, warp etc., and it may not fit properly and seal that hole.

Maybe yours is MISSING?

Mine was like that, old and warped and stiff. I cleaned it up, used some rubber conditioner on it and I had to use an elastomeric sealant to hold it in place, (butyl rubber maybe?) - It was black. It may have been a black non-hardening RTV sealant like Permatex.

Sorry this post is so long but it should be worth it by the end.

By the way it is VERY IMPORTANT to use the appropriate sealants for whatever the job is. Common silicone sealants are not good for redoing a cowl seal. I base that on having quite a lot of experience with sealants used in the commercial/industrial construction industry, the architectural specifications and application of the sealants in the construction industry as well as having redone the sealants on a number of RVs (motor-homes and trailers) where common silicone caulking was probably the worst in terms of failing after a few years - if it lasted that long. Up until 1990 when I left that line of work I had never ever seen silicone specified in any joint on the outside of a building that is exposed to weather and I have been through a lot of new construction specifications and blueprints and 'sealants' were part of the specifications that I read and measured on blueprints very carefully because sometimes we would bid on that part of the project. That was in Minneapolis/ St. Paul Minnesota and in Iowa and sometimes very large construction projects. High quality Urethanes were most often specified for that part of the work. That's one of the reasons why you don't see people hanging off of the sides of high rise buildings and sky scrapers in big cities replacing the sealants around window frames etc. = high quality sealants.

There are some higher quality silicone sealants now days. I used some "Excel" clear silicone recently, which I think is probably one of them I can't remember who makes it. Basically it was a choice of convenience and being a clear sealant.


It rains at some point almost every single day through the long wet and gloomy winter season here in Western Washington) Surface preparation is also extremely important for a good long lasting seal: As clean as possible and if it's a hard shiny surface like metals with a baked enamel finish, scuff the surface where the sealant is to be applied so it has a duller finish rather than bright shiny finish. Steel wool or a fine grit sand paper should work. The scratches don't need to be visible scratches, just dulling that surface provides tiny, down to microscopic scratches that give the sealant something to grab onto and hold better.
Your seal is already done and maybe that 'Flex Seal' over the top will help it last a long time- I don't recall having used that product before. I guess my point is: It pays to do some research into the most appropriate or best sealants to use for a particular application, especially on something as important and as difficult to access as the cowl seal.

Lastly, you stated that you don't think that the leak is anywhere under the hood near where the "air box" is sealed to the firewall. That seal cracks with age and water runs right over it every time it rains) (See "Mystery" about water leaks" comment further below). I can post a photo of that seal with cracks and water ponding on top of the 'box' after a light rain if want to see it.

LOTS of water pours into that area when it rains, through the gap between the hood and cowl, between the fender and hood and from the left end of the rubber V shaped hood to cowl seal which ends about a foot before it reaches the fender well. That seal dumps the water it has collected from most of the hood to cowl gap, off the ends of the seal into that general area and the same on the drivers side. I intend to do something about that in my truck - make a seal that extends all the way to the inside of the fender well where it drains down.

If you have not given that a thorough inspection you should and confirm here that you DID do that so we don't have to pursue that possibility when trying to help.

Also, without photos, everyone should try to be very clear and accurate in their written descriptions because we can't *see* exactly what you are looking at or writing about.

FINALLY a "Mystery" about water leaks and I'll use an example:

You've probably been in a commercial building before and noticed water stains on the ceiling tiles. Apparently a roof leak. So where is the roof leak? Above the spot? MAYBE, but it could be on the roof 50 ft. away from that spot- coming though the roofing and insulation to the metal decking underneath it, travelling along the metal decking where it might find a screw hole and leak down ont the ceiling panel OR to a seam in the metal decking then onto a steel (or wood) roof joist and then down to a ceiling panel or from there onto a structural beam where it flows another 15 ft and finally drips down onto the ceiling panel.

The purpose of that illustration as it applies to finding a leak in a truck is simply this: It's a very good idea to inspect everything and every place where leaks could occur and take care of any defects found, or at least know about them and where they are located to fix them at some other time. Even 30 seconds to dab a little bit of sealant over a crack in a seal might last another 5-10 years before it finally needs a better fix.


These trucks are getting up in their years and at this age tend to require some maintenance attention and any attention and any such attention you give it is worth it in my opinion.

I expect mine truck to last another 30+ years. wishful thinking maybe but that's my approach.

Good Luck Now!

 

I don't know if this applies to you, but I had a weird leak when it rained and just could not find the reason. Finally one day read a thread somewhere, the cab lights. If you have cab lights on the roof the gaskets can get dry and brittle, the water gets in from the roof and can find all kinds of ways to the floor, along the pillars. Some silicone sealant on the gaskets can keep the water out.