Leaking coolant...what does this hose lead to?!

[TheRob]

So, since I got my truck, I've noticed that it loses coolant over time and also steams from time to time from the passenger side of the engine near the firewall. Well, today I finally saw it while it was leaking. The coolant is coming from a tube only about an inch long that sticks straight out of the firewall on the passenger side, about halfway down. It steams because it falls directly onto the exhaust tube right before the cat. Does anyone know what this tube is connected to, what its function is, and/or why it may be leaking coolant from time to time?

Thanks a lot,
-Rob

 

[ctdutro]

If it is comming from the firewall and is coolent then it is the HVAC. Supply or return i don't know though.

 

[tomw]

It is the condensate drain from the A/C evaporator. Humid air drops water when the temperature falls, and it condenses on the evaporator just like on a glass of iced tea.
If it were coolant, it would have a sweet smell. Does it? There is/was a 1/2" diameter line on some that goes from a 'tee' around the back of the head and connects to the bottom of the intake manifold. It supplies 'hot water' to the bottom of the intake to help the fuel vaporize. I still have the factory one on my truck. It is sort of hidden unless you look for it. It does get close to the firewall.
tom

 

[martin]

that sounds like the drain for the hvac. if you are leaking prestone through there it's because the heater rad is leaking a little. Can you smell prestone in the cab?

 

[TheRob]

...

Thanks for the help, everyone. It's definitely coolant coming out of the line. It's green and when it burns, it SMELLS like coolant, for sure. This hose looks like some kind of drain or overflow hose to me. It sticks straight out of the firewall about an inch long pretty much near the bottom of the firewall and directly to the bottom right of the black plastic square box (I don't know its function) that is near the top of the engine bay on the passenger-side firewall. I was thinking maybe a blockage or something in the heater core? I don't know why else coolant would be leaking from the OTHER side of the firewall. Any ideas?

Thanks,
-Rob

 

[TheRob]

...

By the way, this is the 2.5L engine.

Thanks,
-Rob

 

[tomw]

I would bet you have a leaky heater core. That is the only thing carrying coolant that is inside the cab. If 99 is old enough, it is a relatively easy job to change the core. The older trucks have a panel mounted onto the bottom of the heater plenum inside the truck, up behind the glove box. Remove the hoses under the hood, and remove the panel, and the core can be removed. The panel screws come into the box from the bottom. I think you have to keep the old rubber or plastic the core sits on. It's been a while.
tom

 

[TheRob]

...

It definitely looks like the panel is there, and I'm definitely betting it's the heater core that's leaking. Yes, I can definitely smell coolant in the cabin at times. I don't want to remove the heater core as of yet, since I don't have a replacement available, but is there a way to stop the coolant from going back there? As in, is it necessary for the coolant to run through the heater core? I don't have AC in the truck and I don't use the fans or heat or anything.

Thanks!

-Rob

 

[TheRob]

...

Wow...so I was reading the service manual and it says I need to remove the instrument panel including steering column and whatnot. So, I tried it without removing the instrument panel and it doesn't seem to be working. The large plastic chamber (heater plenum?) under the dash will not come out, it seems. Does anyone have any more information on this? Also, I was considering just looping the heater core inlet and outlet lines, as I don't really care for either heat nor cooling in the cabin. Will bypassing the heater core have any negative impact on engine cooling ability in general?

Thanks,
-Rob

 

[Earl43P]

Well Rob, you can do that, just disconnect from both firewall connections and join those two hoses together. Probably won't even notice, if you never use the heat.

 

[TheRob]

...

Thanks, Earl! I figured the radiators were pretty big on these trucks, so it seemed to be an ok plan. Thanks for the info!

-Rob