Please tell me it's not my heater core

[GreyWisent]

Hi everyone,
Recently flushed my cooling system and now it's leaking from the passenger side, from above the firewall shielding... A lot. I checked for leaks, but everything else looks bone dry from the outside . I had to replace more than 2 cups of coolant after a 20 minute drive.

The location of the leak and that it gets worse (doubles) when the defrost is on, to me, points to the heater core. In the past, I would "consume" a lot more coolant in the winter than in the summer.

The collective wisdom of this forum tells me that's statistically unlikely. I really hope you're right. Please help.

This is taken from below the passenger looking towards the front of the car. You can see the drops of coolant forming.

Here's what I did:
Lately, my car has been running hot. I started keeping an eye on it and it works go up to 110C/ 230F after which the fan would kick in and it would drop back down under 95/203, but never under 93/199. I leaned that driving at highway speeds or turning the A/C on when in the city would help keep the temperature under 100/212. Thought perhaps coolant isn't flowing through the radiator well (works better when the fan is blowing), so I started by bleeding the system. That helped a bit, but only for the first drive.
So I came to accept that I need to overhaul everything, and decided I should start with flushing the system, since I've been slacking on changing the coolant (I don't drive much, but haven't changed it since I bought the car). The dark orange color of the coolant told me it's either really contaminated and broken down OR someone before me put stop leak (manual points to this). I did this by draining the radiator and refilling the system with distilled water one gallon at a time - letting the car warm up each time to open the thermostat and allow everything to mix. One upsetting observation was that during bleeding, little clay like pieces (stop leak pellet material?) would come out of the air bleed valve - but curiously, I didn't see them in the coolant that came out of the radiator.
Eventually, I looked under the car during an air bleed process and noticed dripping from the passenger side. Turning the defroster on made it slow down a lot.
Now I'm back to an almost 50/50 mixture, but lose a lot of coolant and the remainder boils of because the system can't pressurize.

My hypothesis is that the guy I bought it from had the same issue and jammed the heater cores full of stop leak. Within a month of driving the car, the degas bottle was empty. Curiously, the coolant loss didn't continue, so I figured it was just that he forgot to refill it and I've been driving around for a while like that. (he also packed the cabin with air freshener trees so I wouldn't notice the burning smell of oil that was leaking from the cam cover. Hopefully, I'll be a lot smarter about my next car.

So anyway, where could this be coming from? The inside of my car is dry. Is there something I can remove or open to see if there's coolant pooling from the heater core?
Or where else could this be coming from? A leak from the degas bottle would have to travel upward to get there and also get behind the firewall shield. And there's a lot of coolant coming out too...

I'm really hoping you guys have some ideas. I don't have the means (time or space) to change the heater core myself, and taking it to the mechanic's would be a huge investment and one that I don't think I can make. Very bummed out that this is probably the end of the road for my car.

Thanks for reading this!

 

[joegr]

A heater core leak would come out the ac evaporator drain, and you would smell it in the cabin.
There are a number of hose connections in that area to check.

 

[GreyWisent]

Thanks Joe. They all look dry, but I will check again and again. I can smell it a bit in the cabin, but it seems too faint for the amount of water that's escaping.

Where's the AC evap drain? I thought that was it.

Besides that, is there something that I can quickly remove from my console to look around and see if there's water in there? If I remove my stereo, will I see anything?

Does that 8C289 metal bifurcated pipe behind the engine, that the air bleed hose attaches to ever break/crack? I don't see much talk about it or people replacing it, so I assume no. How does one even get do it? I imagine it attaches to the firewall and doesn't just float there, so that's a point I'll have to check. I faintly see two attachment points on the diagram.

 

[joegr]

To get to the heater core:
Dash Board Removal Thread

 

[GreyWisent]

Yup. Went through that thread Friday night and wanted to cry (that syringe was probably left there by the previous guy who took apart the dash and needed some drugs after the ordeal).

Even after that, I can't tell if I would be able to see anything with just taking the stereo and centre console out, so that's what I wanted to check.

Joe, you mentioned somewhere that there are 2 heater cores in this car... Is that correct or am I delirious? In that thread, I only see one and the AC evaporator.
Also, I saw a mention of some valve inside the cabin, connected to the heater core. What's up with that? From what I see, the heater core has some pipes attached to it that connect directly to the hoses in the engine bay.

 

[GreyWisent]

Sorry, any help with this?

Where's the AC evap drain? I thought that was it.

Does that 8C289 metal bifurcated pipe behind the engine, that the air bleed hose attaches to ever break/crack? I don't see much talk about it or people replacing it, so I assume no. How does one even get do it? I imagine it attaches to the firewall and doesn't just float there, so that's a point I'll have to check. I faintly see two attachment points on the diagram.

View attachment 828570051

 

[joegr]

There is a dual core, two cores in one unit. No, you can't see the heater cores by just removing the radio. There are no valve under the dash. The DCCV is at the radiator.
Your picture is not clear enough for me. Maybe the evap drain could drip on that.

 

[toby1234]

I flushed my system once and left the flush in there for longer than I should have. My heater core started leaking on the driver side kind of like where your picture shows a leak. Also, my carpet was wet near the throttle pedal. It smelled like coolant without a doubt.

 

[joegr]

I flushed my system once and left the flush in there for longer than I should have. My heater core started leaking on the driver side kind of like where your picture shows a leak. Also, my carpet was wet near the throttle pedal. It smelled like coolant without a doubt.

As you now know, those cores are pretty thin.

 

[GreyWisent]

Thanks Joe! I will label that picture better so it makes sense and re-upload it.

I flushed my system once and left the flush in there for longer than I should have. My heater core started leaking on the driver side kind of like where your picture shows a leak. Also, my carpet was wet near the throttle pedal. It smelled like coolant without a doubt.

Thanks Toby! What did you end up doing? Junked the car? Changed the heater core? Did you do it or mechanic? Or did you plug it with that quick fix solution whose name shall not be spoken?

I avoided using any flushing solution exactly because I was expecting something like this... sadly.

 

[toby1234]

The heater core is cheap, but getting to it would have been a huge ordeal that I didn’t want to go through. I decided to bypass it along with the dccv.

 

[GreyWisent]

My thoughts exactly. Looking at the heater bypass as a temporary solution until I either have the time/space to do this or find a decent mechanic.

If you don't mind me asking, can you give me more details about how you went about bypassing the DCCV? Did you remove and block off piping OR did you clamp it off? What's your set up?

Did you also bypass the auxiliary pump? Been looking at DeviLSh's post on that here: LS Weight Reduction - Discussion Thread
It looks like he's basically running a hose from the hard line behind the engine, all the way to the t-stat housing where the aux pump flows into (and blocking off the t-junction in the upper radiator hose).

Is clamping the heater core outlet (keeping the DCCV closed at all times) to as to eliminate back flow an option? Or all 3 hoses as a precaution. I saw someone recommended looking at one of these hose pinchers:
(i.e. these guys: Fluid Line Clamp Set 4 Pc) Worth a look, at least as a test. Don't think it would hold up anywhere close to the right pressure.
Right now, with the engine cold and just started, the leak happens immediately if the heater is on, but not if the heater is off - eventually it leaks (with increasing pressure it locks up).

 

[toby1234]

It was a while ago, but here’s what I remember. For sure, the hose leading to the dccv from the upper hose had to be blocked off. I put a cap and clamp on the upper hose fitting and the hose I left alone since no water entered the system. I just bent it and tucked it out of the way.
Then, I disconnected the heater core inlet hose at the firewall and plugged it off using a big bolt and a clamp. The inlet is the top left hose, there are 3. With no water entering the core, I just left the inlet alone. Didn’t bother covering it, but you could I guess.
Finally, and this is going off of shady memory, the hose under the thermostat housing that goes to the auxiliary pump needs to be disconnected and plugged on both ends.
That’s it I think. Not too bad, but I had to stare at the system for a while the first time just to figure it all out. A/c worked great after that!

 

[GreyWisent]

It was a while ago, but here’s what I remember. For sure, the hose leading to the dccv from the upper hose had to be blocked off. I put a cap and clamp on the upper hose fitting and the hose I left alone since no water entered the system. I just bent it and tucked it out of the way.
Then, I disconnected the heater core inlet hose at the firewall and plugged it off using a big bolt and a clamp. The inlet is the top left hose, there are 3. With no water entering the core, I just left the inlet alone. Didn’t bother covering it, but you could I guess.
Finally, and this is going off of shady memory, the hose under the thermostat housing that goes to the auxiliary pump needs to be disconnected and plugged on both ends.
That’s it I think. Not too bad, but I had to stare at the system for a while the first time just to figure it all out. A/c worked great after that!

Thanks for racking your memory for this info. It confirmed my thoughts. I clamped** that top passenger side hose of the heater core that connects to the hose coming from the air bleed pipe - I think that's that actually the heater core outlet pipe though - and kept the heater off (DCCV closed) and didn't have water dripping for the hour or so that I tested it. This to me confirms my worst nightmare. Will be taking my dash apart this weekend.
Engine still overheats though, so it's either (or a combination) of pressure still "leaking" through my clamp, the degas bottle (& other plastic parts) being cracked) or my radiator being clogged - can be likely because stop-leak was used in this car.

Here's where I get a bit confused though, and would like to ask if someone could confirm this: I always thought that the water flow in the pipe that connects to the air bleed valve + hose is towards the degas bottle, coming from the joint (#8C289) between the DCCV and heater core inlet, when actually it flows AWAY from the degas bottle, then joins water coming OUT of the heater core and goes to the DCCV...

At least that's what the Gen2 diagram shows, although it's a bit fuzzy and I couldn't find a better resolution one:

The Gen 1 diagram confirms this (and I imagine that they didn't switch the flow):

This leaves me scratching my head a bit.
Where is the air from the air bleed valve coming from? If water flows away from the degas bottle, wouldn't the air that's pushed out from the bleed valve be coming from the degas bottle too?
And if that's the case, wouldn't the air bubbles just rise to the top of the degas bottle and not even go through that pipe - i.e there would be no air to bleed? (This one can't be right).
Is the air that's meant to escape travelling in the opposite direction of the coolant through that pipe? (I don't think this is right either.)
As far as I know, the air bleed valve is not directly connected to the degas bottle - just attached to it for support.
(I think) I've read through all the threads discussing cooling, but never came across a physical explanation for this...



** For the clamps, I got my hands on a set of these https://www.amazon.com/Powerbuilt-648526-Hose-Pinchers/dp/B002INOOPE and used both of them since that hose is pretty fat. Don't expect it's a proper seal and I also expect that I damaged the hose, but will deal with that later. Was hoping to buy these: Fluid Line Clamp Set 4 Pc but I couldn't get them in Canada in time.

 

[joegr]

Air from the heater bleed comes from the heater core and the feed lines running to it. The degas bottle gets air from the engine air bleed hose that attaches to the top of the crossover/thermostat assembly. This is the small hose that goes to the top of the degas where the small metal tube goes down into the degas bottle. The bigger hose at the bottom of the degas is a return hose. It merges into the heater return hose that returns coolant from both of the cores back to the engine/radiator.

 

[GreyWisent]

The degas bottle gets air from the engine air bleed hose that attaches to the top of the crossover/thermostat assembly. This is the small hose that goes to the top of the degas where the small metal tube goes down into the degas bottle.

Yep! Number 11 in the coolant flow diagrams.

The bigger hose at the bottom of the degas is a return hose. It merges into the heater return hose that returns coolant from both of the cores back to the engine/radiator.

Exactly. Via 8C289 pipe/hose.

Air from the heater bleed comes from the heater core and the feed lines running to it.

This is the part that I don't understand. What you describe makes perfect sense, but I don't physically see it happening. Looking at the diagrams and actual car, both heater core feed (inlet) lines run untouched from the DCCV to the heater core. I don't see where the connection between those inlet lines and the bleed would be made. Also, the air bleed hose connects into the bifurcated 8C289 pipe, which then connects to the heater core return line, as you described above.

(pipe + hose 8C289 bifurcates to connect to the degas return hose and the heater air bleed valve, then flow into the heater core return line)

(Heater core inlet lines direct from DCCV; top two in the portion where all 3 lines run parallel. 8C289 hose/pipe that connects to bottom of degas and air bleed port joins the heater core outlet line, through the clamp marked as #5)

So, I'm still confused. Is the answer then that air travels in the opposite direction of the degas return coolant (bubbles "backwards")?

 

[joegr]

There's very little return from the degas. With the bleeder open and the DCCV valves open, the air easily overpowers any minimal flow in the other direction, particularly the way that pipe is designed.

 

[GreyWisent]

Thanks again, Joe.

There's very little return from the degas. With the bleeder open and the DCCV valves open, the air easily overpowers any minimal flow in the other direction, particularly the way that pipe is designed.

If the geometry of that 8C289 pipe were any different, this probably wouldn't work at all. It's becoming more and more obvious to me that some very smart guys designed this car to be in perfect equilibrium and any changes/modifications that perturb that throw it wildly off balance. Obvious implication is that it's best to keep everything stock and OEM, unless you enjoy headaches. Same with taking shortcuts.


Any idea how the DCCV works if not powered/disconnected? Is its unpowered state an open direct line between the aux pump and the heater core + degas bottle return? Just curious...

 

[joegr]

...Any idea how the DCCV works if not powered/disconnected? Is its unpowered state an open direct line between the aux pump and the heater core + degas bottle return? Just curious...

Unpowered is fully open. Note that under the right circumstances, the car can keep the valve powered closed until the car goes to sleep. Also note that it will intentionally open it at times while the engine is running (cold engine) or the aux pump is running (after shutdown) to flush fresh coolant through the heater cores to extend the life of the cores.

The beauty of really well thought out design is that it looks so simple that you don't realize just how much thought really went into it.

 

[112 LS]

Very interesting indeed.

This would explain the noises I was hearing under the hood recently. My car was super low on coolant, and after shutting down I could hear the coolant sloshing around in there. Had me wondering wtf was going on in there.

 

[smegun]

time to look at my ls again last time i changed the dccv and i couldnt get it to stay cool even at idle it would overheat i was reworking my steps i managed to score a couple dccv valves but still no go getting foam out the bleeder i saw a few drips and assuming my heater core is bad not certain there may be other places to consider but out of the need for testing the car i want to bypass the core in hopes of a stable enviourment i did have it bypassed but did notice i had a problem with my bottle that no movement is a result of bypassing it wrong even if it didnt overheat it could lead to problems possibly anyway im putting a diagram up here to ask if anyone has tried to encorporate the secondary pump in a bypass ( like use a T )the last time plugging off the dccv valve leaves the degass bottle without its firewall line as to be uneffectual .... also im looking for a part number for the plug for the manifold line that runs to the throttle body cooler wondering if its sucking in air leaking ive got a few drips from the firewall area but i havnt been able to trace the lack of pressure i assume is causing a overheat situation

 

[smegun]

the first time i unplugged the secondary pump put a cap on the return from the pump on the water inlet housing and two on the T junction of the main upper radiator hose it worked but you lose functionality like a proper circulating degass bottle and you dont the benifit of the secondary pump and the security of more fluid flowing in the car ....... its still a hot spoiled women he ha