ForeverDrivin

A coolant leak just popped up in my 98 v6 a week or two ago and I believe it's the heater core or the pipes/lines leading too it. I noticed my passenger side cats were smoking and the inside of my car now has this bad gas/coolant smell to it (the gas could be from a gas tank I keep in the trunk since my fuel gauge doesn't work) and I found where the coolant is coming from (seen in the picture). I want to try and fix it myself but honestly I have no idea where to start, as I've heard some of these repairs can require taking the whole dash out. Is this a plug I just need to get and put in or do I need to tear up my interior and get a new heat core? I also know of this pour-n-go stuff that's supposed to seal gaskets without messing with the rest of the system but I don't know what to do for sure. Thanks to anyone who can help.

08'MustangDude

Leaking outside the car is better than inside the car. Can see the clamp has
coolant on it.

In order to determine where, you will have to run it hot, shut it off, pop
the hood, and look around that area. Pressure will build up when the
motor is off, so you can see where it is leaking from. Hopefully, it's
just the hose, where clamps on to the core, or a fatigued clamp that
needs replaced. If it's the fitting on the core, then you would have to replace
the core. JB Waterweld may hold, or the hose might be able to be moved
forward some and reclamp to unexpose a hole or crack.

If it is a SMALL hole or crack, sand it down and JB Water Weld it, and let sit
for at least 8 hours, and clamp the hose over it. You may need to replace that
clamp with a band clamp. I fixed a hole in a rad with it, and it lasted 6 months
that I know of, as I traded it 6 months later.

Hose
Core
Fatigued Clamp

Those are the possible culprits.

ForeverDrivin

So where are these hoses? Do I still need to take out the dash and look around inside for them or are these hoses somewhere around the engine? I know where the leak is, it's coming from the hole above the headers in the picture. I dont know why it's called a clamp unless a hose is supposed to be there, but I assumed that hole was for ventilation. If a hose is supposed to be there then that'll be super easy, but I don't understand where these hoses are located

08'MustangDude

The hose in the picture, with the clamp, WRONG one, sorry...

It's these:



IF it is the heater core, then yes, the whole dash has to come out...

You said it's coming from the hole above the headers in the picture, well,I don't see any hole,
or what the hole is in. If it is in one of the lines to the core, those lines are replaceable, the
core does not have to come out to replace the lines.

They come off the motor here:

So, follow them back to the core and check for leaks. The one with the circle
around it is just a repaired hose...

ForeverDrivin

Thanks man, I appreciate all the time your taking to help me, but it doesn't seem to be the lines. In my picture, you think I was trying to circle one of the lines, right? Well look in between that line and the bigger line above it, and there is a black "port" sticking out of the white background, and that's what's leaking the coolant, I've seen it drip and you can even see that it's wet if you look hard enough. Do you know what that means?

08'MustangDude

No, I did not think you were circling one of the lines, I don't know what that is.
Looks like a bolt.

I still don't know what I am looking at, it's too close. Looks like your coolant
reservoir is there, and I don't see that in under hood pictures of other 98s.

Could just be leaking out of that big hose, dripping down; I see the stained metal clamp.

ForeverDrivin

Well here, I made a short video going from the front of the car into the engine bay and the spot of concern. I keep calling it a "hole" because I just don't know what it is so sorry if that caused confusion. Also, I am able to stick my finger directly into it, so the coolant has to be leaking from it.
video: https://drive.google.com/file/d/13VU25oaBZGc5bTZvUqSmlmaqFzHWB4j3/view?usp=drivesdk

08'MustangDude

Oh! HA, that's the drain for the A/C. Are you sure it's coolant and not condensation from the
condenser? I the core leaks inside the car, it would be getting on the floor too. You can
put another hose in there to angle it away from the header pipe.

Did this just start with warm weather, and you using your A/C?

Also, if your coolant level in the reservoir is not depleting, it's not leaking.

ForeverDrivin

So that's what it is! Good to know, but I'm sure it's leaking. We will randomly find puddles when it's parked, sometimes it leaks and sometimes it doesn't. When you're driving you can sometimes just hear the sizzling as it drips onto the headers and everytime you park it, if you look underneath the car you will hear the sizzling and see the smoke. Plus my coolant reservoir IS depleting.

And yes actually, it did start happening when I began to use the A/C!

08'MustangDude

When you use the A/C, water condenses inside the housing, and drains out that
hole. If it does NOT happen when do not use the A/C, then the core is not leaking.
Yes, there will be a puddle there if you idle for even a few minutes with the A/C on.

However, if the core is leaking, for now, that it's warm out, you can rig up a bypass.
You would basically take the input and output hoses and connect them
together. You are going to have to take the dash all apart to replace the core,
it's not fun. Paying for it, is also going to be probably more than you wish
to even consider paying -vs- what the car is worth...

You can try a bottle of any rad leak repair stuff you dump into the coolant.
IT does work when the redirection are followed to the the letter, but not for
more than 6 months to a year.

When the A/C is on, the motor runs a little hotter, with the extra fuel needed
to spin the compressor. So, it started leaking with the higher pressure with
the higher heat.

You can also replace that with a tube, so you can angle it away from the header
pipe, something like this:


Or any other kind of right angle tube to get it dropping away from the header.