Best way to drain heater core

[Slideways]

Is there an easy way to tell if the heater core has a leak? I can't spot anything obvious. Maybe it is leaking underneath?

Symptoms:
Burning smell coming from the vents when the heater was on
Coolant temp gauge staying near the first dot 75C when the heater was on. Coolant temp goes back to 80C when heater is off.
Coolant level just below full

[bigjae46]

I believe the HVAC box has a drain which drains onto the top of the transmission?

If you're that far into it, why not remove the heater core and inspect it?

I'd be inclined to blame the burning smell on something in the engine bay.

[Slideways]

I believe the HVAC box has a drain which drains onto the top of the transmission?

If you're that far into it, why not remove the heater core and inspect it?

I'd be inclined to blame the burning smell on something in the engine bay.

Removed the heater core and it has a white residue (dried coolant) underneath - basically where end tank is connected (crimped?) to the core and on the opposite side where the two pipes connect.

[bigjae46]

Removed the heater core and it has a white residue (dried coolant) underneath - basically where end tank is connected (crimped?) to the core and on the opposite side where the two pipes connect.

That's odd to see that. Did it leak into the drain at all?

The only thing I could think of that would cause that is someone doing an old school double din conversion where you had to modify the insides of the HVAC box.

[Slideways]

That's odd to see that. Did it leak into the drain at all?

The only thing I could think of that would cause that is someone doing an old school double din conversion where you had to modify the insides of the HVAC box.

It is hard to tell as some coolant spilled into the drain during removal. Looking at a few images of used heater cores on eBay and one thread on E46F, they all have that white coolant residue. They are all getting to be 20 years old at this point.

[George Hill]

I feel like almost every heater case I pull apart has some white residue in it, never seen one physically leaking though.

[Slideways]

I feel like almost every heater case I pull apart has some white residue in it, never seen one physically leaking though.

Yeah, it could be aluminum corrosion. It is weird that it is only on one side.

[bigjae46]

Yeah, it could be aluminum corrosion. It is weird that it is only on one side.

Probably where the end tank was brazed onto the core? Could be contamination in the braze causing some corrosion. I believe end tanks are usually brazed meaning a dissimilar metal is used. Eventually, that will result in some sort of corrosion.

[Slideways]

Update - With the new heater core, the coolant temp now stays right at 80C and no longer dips back down to 75C when on the freeway or when it is below 50F outside. Heater on full, it still maintains 80C.

There is still a slight smell from the center vents for the first minute after startup. George Hill would the FSU or blower motor cause this?

Here is a picture from another thread of where the white deposits like to form on the heater core -



Either that is dried coolant from a small leak or corrosion from water vapor coming from the A/C system.