Missing coolant

[Casey]

Heater core leaks can be caused by an improper hose connection as has happened to Dirk and also the joint where the inlet and outlet tubes connect to the body of the heat exchanger itself. These joints use o-rings to seal the tubes and are crimped in place. A close visual inspection can show if that’s the cause of your leak, and if that’s the case it may be fixed by re-crimping those fittings.

Are these o-rings on the engine side of the firewall?

I found the missing coolant, haha, it's all under my driver side floormat and on the plastic trim ledge above my shins!

[foama]

What you could do:
Push the driver seat all the way back, and remove the horizonal piece of plastic cover that would be above your shins. It is held by three small plastic clips that need to be unscrewed with a very small screwdriver. Take them out carefully for reuse. When the clips are out, the cover is loose.
Then get your head right next to the gas pedal, looking towards the heater assembly, which is most uncomfortable.

There you can see two shiny coolant pipes coming through the firewall towards the cabin and going into the heater assembly and the heater core. There is one sort of bulge in each pipe.
That bulge is the crimped connection with O-rings as a seal.

If some goof bent or twisted it too much during installation, it will have become deformed and leak. Probably that can be repaired with the help of a variety of good pliers. If you take a good look you will see.
If the leak actually does come from the heatercore itself, you may want to consider bypassing it, provided your Florida climate lets you get away with that. Heater core replacemaent is not trivial, see a few threads in this forum.

[Eggman]

Are these o-rings on the engine side of the firewall?

No. These o-rings are located at the heat exchanger (heater core) where the aluminum tubes meet the body of the heat exchanger itself. These joints allow the aluminum tubes to rotate and are crimped in place.

[foama]

Are these o-rings on the engine side of the firewall?

See post number 22

[Casey]

What you could do:
Push the driver seat all the way back, and remove the horizonal piece of plastic cover that would be above your shins. It is held by three small plastic clips that need to be unscrewed with a very small screwdriver. Take them out carefully for reuse. When the clips are out, the cover is loose.
Then get your head right next to the gas pedal, looking towards the heater assembly, which is most uncomfortable.

There you can see two shiny coolant pipes coming through the firewall towards the cabin and going into the heater assembly and the heater core. There is one sort of bulge in each pipe.
That bulge is the crimped connection with O-rings as a seal.

If some goof bent or twisted it too much during installation, it will have become deformed and leak. Probably that can be repaired with the help of a variety of good pliers. If you take a good look you will see.
If the leak actually does come from the heatercore itself, you may want to consider bypassing it, provided your Florida climate lets you get away with that. Heater core replacemaent is not trivial, see a few threads in this forum.

Thanks! That gives me some hopes. Yes, I already bypassed it so it would stop making a mess. Hoping I can fix these o rings!

[Casey]

What you could do:
Push the driver seat all the way back, and remove the horizonal piece of plastic cover that would be above your shins. It is held by three small plastic clips that need to be unscrewed with a very small screwdriver. Take them out carefully for reuse. When the clips are out, the cover is loose.
Then get your head right next to the gas pedal, looking towards the heater assembly, which is most uncomfortable.

There you can see two shiny coolant pipes coming through the firewall towards the cabin and going into the heater assembly and the heater core. There is one sort of bulge in each pipe.
That bulge is the crimped connection with O-rings as a seal.

If some goof bent or twisted it too much during installation, it will have become deformed and leak. Probably that can be repaired with the help of a variety of good pliers. If you take a good look you will see.
If the leak actually does come from the heatercore itself, you may want to consider bypassing it, provided your Florida climate lets you get away with that. Heater core replacemaent is not trivial, see a few threads in this forum.

We are finally getting some sub 40F temps here in Florida and I got motivated to check this out. Bummer that it doesn't look like the crimp connections are a problem. Unless, it's leaking on at the connection on the inside of the plastic box. When it's running I can see coolant leaking out the seam of the plastic box on the same side as the connections and the lower side of the box. Was hoping to drive with heat tomorrow morning!

[Fummins]

If it is the heater core leaking, (which it sounds like it is) at least there's a faster way to replace it now without tearing your entire car apart. There's a thread about it somewhere here.

[Casey]

If it is the heater core leaking, (which it sounds like it is) at least there's a faster way to replace it now without tearing your entire car apart. There's a thread about it somewhere here.

Thanks. I did see that thread. I'm not convinced it's not the o ring. It almost seems like the leak is intermittent. I tried squeezing on the connections and thought for awhile I had it fixed. Such a hard place to get access I couldn't tell if my squeezing was doing anything or not. I'm going to have heat in the morning tomorrow though! I left it all connected but carrying my bypass and a jug of coolant with me on my long commute.

[Casey]

I'm not celebrating yet but monkeying around with those crimped fittings may have helped. I couldn't really tell if I was accomplishing anything but I made my 80 mile drive this morning with blazing heat and no sign of a leak.

I also added a screw down hoseclamp to the hose on the engine side of the firewall. After testing it, it was leaking out there too. I'm pretty sure it wasn't leaking there before and it was just an anomaly after taking out my bypass but perhaps that was the original issue and I just couldn't see it leaking there before. Keeping my fingers crossed!

[Dirk Diggler]

I'm not celebrating yet but monkeying around with those crimped fittings may have helped. I couldn't really tell if I was accomplishing anything but I made my 80 mile drive this morning with blazing heat and no sign of a leak.

I also added a screw down hoseclamp to the hose on the engine side of the firewall. After testing it, it was leaking out there too. I'm pretty sure it wasn't leaking there before and it was just an anomaly after taking out my bypass but perhaps that was the original issue and I just couldn't see it leaking there before. Keeping my fingers crossed!

I had this exact same leak in the exact same spot, in my wife's G4. Turns out the car had engine replaced and replaced poorly. The ripped up the piping causing a small coolant leak.