It is rather Ironic that I see several threads about heater cores in the 85 trucks. I have been trying to figure out where the moisture is coming from in my floor board. I first thought it was the windshield. So 2 weeks ago, I had the window opening cleaned up, rust removed, body work, and painted. Then I had a new windshield and new Toyota trim(300 bucks worth) installed. I still have the moisture.

I have looked all over but don't see a leak from the heater core. The heater core does make this gurgling noise and has for a long time. Yesterday, I took the passenger floor mat out and left the driver side in. I went on a trip. I got back home. Driver side soaked, passenger side dry. I am still shaking my head. The floor board seemed awful warm to me like right behind the brake and accelerator pedals. Is it possible that the floor mats are making the carpet sweat? I should add that the insulation under the carpet doesn't feel wet, just the carpet itself.

Please help, I am scratching my head and pulling my hair out.

 

Got somthin to check....
Passenger side firewall where the wiring harness comes through. Theres a gromit, water drips on it in some cases it leaks into the cab and the water follows the wiring onto the carpet.

 

Take a fender off and youll see a pocket up under neath the cowl. A lot of yota rust in there cause the water just sits there

 

Are you alking about the cowl across under the windshield? If so, mine is clean as it can be. Just had that off and there was no rust under there but I may need to take it off to checkk for leaks anyway.

 

I've heard that the seam in the far corners of the cowl area have some body sealer that is prone to cracking and letting water leak into the cab down the inside of the firewall. I think I have this problem on my '85 as the floor boards will get wet in a hard rain. I used to have a windshield leak but fixed that by replacing the factory trim and sealing it up better.

 

Yes but the cowl directs the water towards the fender into a pocket. The pocket is only visible if you take the fender off. You'll see a little hole in the inner fender area close to the fire wall. Take a flashlight and shine inside along the edges and see if there are any cracks or rust holes. ALOT of people are having problems in this area. I have a hole abouyt 1 inch by 5 inches. To fix it, you have to take a small cut off blade for a grinder and cut out a hole in the side of the inner fender big enough to fit your hand in there to re seal it.

 

Thats very interesting I have the same prob. Ill check that also, thanks on the info .
_______________________
85 4runner sr5 33's
2inch body lift

 

UPDATE sort of. It flooded all day yesterday. I have NO moisture in the floor board. SO that still makes me wonder where the damn moisture is coming from. SMH

 

Well I have left the floor mats out and no moisture, despite a couple days of storming and driving. So the rain nor coolant is getting into my truck. Why would the floor mats make the carpet sweat? That is all I can figure is going on. Thanks

 

How is the floor pan under the carpet? I'm wondering if you have rust under the carpet (or on the firewall) and when the floor mats are in place the moisture that makes its way to the carpet does not evaporate off, thus accumulating and soaking the carpet.

 

No sir, no rust or anything. The floor is perfect. I just can't figure it out other than the floor mats but the moisture has to be coming from somewhere to start with.

 

Are you in and out of the rig a lot in a day and the moisture is just tracking in on your shoes? Stick with it and you'll find the source.

 

Could be the leak is very slow and with the floor mats out it evaporates as fast as it leaks in, but with the floor mats in, the moisture is trapped under them. Mine has a slow leak like this. Usually just throw the floor mats in the back for a few days and it dries out.

 

Do you think it is the heater core? My heater core has always had a gurgling noise to it. I have thought about replacing it, but just haven't been that froggy. Would the gurgling noise be any indication of a leak or problem ?

 

The gurgling sound is due to air (or other gas) trapped in the cooling system. Try burping the cooling system by parking w/ front end uphill. W/ engine cool, open heater valve and open rad. cap, run engine up to temp. and let the t-stat open and see if any air bubbles escape. If so, top off with coolant.

Might try a cooling system pressure test and see if there is a leak under high pressure.

But could also be due to a head gasket leak letting exhaust gas leak into the cooling system. Have had this issue a few times and has always been due to a HG leak. Pressure test or a chemical test on the coolant (NAPA sells a test kit for this) will confirm or rule out this cause.