Yep, the round piece is the back part of the drain tube. Sounds like it must have some gunk in there restricting it. As was mentioned, probe around in the drain tube gently with a piece of coat hanger and see if you can open it back up. You don't need to push it in very far.

 

I wish I had a spare box to be able to take a picture of it, but the heater box kind of tapers to a V at the bottom where the round drain is. For the life of me, I can't figure out how it could ever leak into the cab, it should literally take it filling halfway up to start to leak, but it doesn't. I wonder if it is the fan blowing the drain water back thru the hole in the firewall......... I know for a fact mine has had the heater box out at least once, wonder if there is a seal......

 

i keep trying to clean the drain out, last night i believe i started to get alittle more water to come out, would it hurt to blow alittle air in, kinda like back flush it

 

Shouldn't hurt, but be aware, the housing forms a valley down to the drain, so what at first feels line an obstruction is really the part of the housing that directs the flow.

 

i'm getting water out of the drain, i'm using a 8 gauge wire to probe around in there with, water streams down my arm, but it is still dripping from the housing inside

 

oh yea, another thing i've noticed is i don't hear the water sound coming from the housing. like it was full of water.

 

If you can get to it, try running a bead of silicone around the tube where it passes thru the firewall.

The tube is molded right into the lower housing, so if there is a leak other than water being blown back and getting thru the hole in the firewall, you have a broken heater box.....

Like I said, I think it may be a case where after the box has been out once for a core exchange, it never seals right again.

Have you tried the 90 degree elbow yet?

 

not yet, fixing to go get one now, i'll put that on an see what happens, then i'll do the silicone, and if that don't work i'm going in, it ain't like i gotta lot of dash to take apart, ck back i'll keep you posted, thanks patdaly for all you're help, maybe it's as simple as an elbow

 

Had an 01 gasser at work that blew back. Went to the plumbers and got a copper 90 and it was a snug fit. Fixed the problem. And the gassers don't have the air filter box there to help block the back pressure

 

You remember what size?

I like that idea better than the rubber..........

 

That was a long time back but I think it was a 1/2" with the upset flare on it for soldering. If you know the ID of your rubber hose then just measure the ID of the 1/2" and 3'4" copper at the hardware store although 3/4 plus the upset seems to big best I recollect. I didn't even put a sealant on it to keep it in place and it was still on there when I walked out the door for the last time.

 

Yea, I had forgot about the offset, it would have to be 1/2".

Now I wonder if a 1/2" rubber elbow would work..... I just bought what someone on here told me to..........

 

You might even check the pvc and cpvc fittings. One of them may fit and cheaper than the copper. They have the pvc with threads too and that will be a different ID than the glue up one. Then there's that "crazy pipe" stuff (gray or black) for lawn sprinkler systems.

 

i found a vaccum elbow at advance auto, it has a flare on one end, it fits tight over the drain, and i think it's working, drove my truck to get it aligned, when i got home didn't notice any drippage, thanks everyone, ya'll been a great help

 

Hope that's it, like I said, I went nuts, didn't believe it was possible to be that simple of a fix, 3 years later, still bone dry.