Heatercore leak? or Hose?
 

Hello, Wondering if anyone knows if my problem is related to coolant leaking from the core itself.

I'm loosing lots of coolant when the car is running, it leaks (ABOVE) the transmission, and on inspection I don't see coolant coming from the heater core lines, and the return is bone dry.

I have checked both outside and then poked around the heater core in the cabin, and have not seen any moisture especially if it was from inside. (No smell inside)

Under my car, you notice pooling on the painted unbody where the transmission is housed and the seam across that (overlap), it drips and pools on the transmission and then drips down onto the concrete.

I have no issues with smell or build up on my windows to my knowledge.

Would my best bet be, capping the line off the engine to the core and seeing if I get any leaks as it's apparent on idle? Or is it simple as my return line is old and should be replaced. (1990 jdm s5 t2)

These leaks are tough to find. Start the car, let it warm up, then shut it off. Listen around the engine bay if you can hear any hissing or bubbling (near hoses). Gently squeeze the upper radiator hose, you can also listen for leaks easier. If you see nothing at the "main" hoses, it could be the thermowax coolant line. That would be right behind the throttle body, above the transmission. It's a tougher, smaller hose to access.

"I'm loosing lots of coolant when the car is running, it leaks (ABOVE) the transmission, and on inspection I don't see coolant coming from the heater core lines, and the return is bone dry."

First thinks that came to mind are:
1) Under the manifold on top of the block there is a hose that can leak that is quite common. It could run down the transmission.

2) I had the driver's side heater hose coming out from the firewall leak for a long time and couldn't find it. It would leak slow so that the drips would trail down the hose and drop onto the top of the transmission onto the floor. I did a tactile inspection to find it.

It sounds like a cooling system pressure tester could be a great help in this situation along with some UV dye and the light.

Ok.
 

I still have a top mount and broke the one of the four bolts off woot!

Lol, Ok would like to thank everyone for being helpful first of all.

(Yesterday)
Current situation! Squeezed the hoses sounds fine aside from air quite a bit lately.
(Feeling more then sound that is)

I get no hiss as we would assume, BUT! I did "Gain", coolant as I started it at FULL came home after normal 60km city stroll (15Minutes), turned it off check the coolant level and BAM!!!! more coolant? good cup or two at that.

The hoses I see that do not leak are The Return, rear iron to firewall, small heater hose near rear iron.

I'll add my A/C was deleted.... I WISH I had those.
I cannot say I've heard of this I'm only aware of 3 hoses
(Rear iron to firewall, Return, Heater hose, theirs a forth hose? If that is existent, I think I should grab my mirrors and dig.

^It's tough to see with the top mount in the way. There is a small hose from the rear iron that feeds the thermowax. Then that line runs to the BAC, then another line to from BAC to the back of the water pump. You will need a mirror to see the rear hose, which is probably what is leaking!

FWIW, you do not want the leak to be the heater core. I'll never replace one of those again. Anyways, you can rent a ptessure tester from most chain auto part stores. Tiny leaks suck to find. Been there wiyh mne.

you can't Gain coolant.
You gained AIR in your system.

i had similar problem i thought it was the heater core so i took my whole dash out and just to find out it was good problem was the inlet part was bent from over tightening the hose and it was leaking inside the car

All good I think?
 

Didn't run into a leak anymore, I guess it was the rear iron going into the firewall dripping off that, as It wasn't wet inside and looked 100% fine aside from the one I re-tightened and threw a newer clamp over.
(I think my AC delete worked but their was a slight mishap or "leftovers", cumming out while the logicon was on a different setting.

All good NOW! but I do get a fair bit of "Air" into my system so!

You guys think a cheap aftermarket coolant reservoir Will get rid of that turd.
*I started another topic on this for the neck as you need a high point for the reservoir to work properly*