1G Heater core leaking?

[dwb]

In my 1g I've been smelling antifreeze when I turn the hvac thermostat to heat after the engine is warm. I'm always using fresh air intake and the blower is always on. Only very briefly is the smell noticeable and only when heat is on.

Water pump and all the hoses are new. I have an intermittent pinhole leak on the top of my radiator but I dont believe that's the source. No other leaks I've noticed. Coolant level hasn't changed other than what I expect from the radiator pinhole.

Could this be anything else besides the heater core?

 

[92AWDHX40]

could be look under the dash for leaks.

 

[dwb]

could be look under the dash for leaks.

Hard to tell. Maybe a little sus but feels dry.

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[steve]

Make sure the pinhole leak is gone and you still have the issue before ripping into the dash. The smell of coolant can vent out of the engine bay and into the fresh air intake.

 

[dwb]

I did a little experiment yesterday. I left the heating control at cold and switched to cabin air recirculate. I drove about 15 minutes like this, engine was up to temperature, fan on high, and flipped the control to heat. Right then I very briefly smelled antifreeze. So this was not a smell originating from the engine bay. Furthermore, I've noticed it takes longer than it used to to start blowing heat. Seems a little too coincidental that I do not have a heater core issue.

I found a 2g dash removal write-up (https://www.dsmtuners.com/threads/2g-dash-removal-instructions.379111/). Anyone have one for a 1g?

 

[SixBolt_16G]

Youtube videos are always hit or miss, but maybe this will help?

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[Jk's97DSM]

You need to pressure test the system. Put it at 15PSI and if it goes down start spraying soapy water on hoses and components. If it doesn’t maintain pressure there is a leak that must be fixed.

 

[1990TSIAWDTALON]

I am right with @Jk's97DSM .
Rent a pressure tester (free) and bring the system up to 15lbs max. Watch for pressure drops. You can put dye into the antifreeze and use a UV light to see any coolant leaks. I think the coolant I am running has dye in it already.

 

[dwb]

You need to pressure test the system. Put it at 15PSI and if it goes down start spraying soapy water on hoses and components. If it doesn’t maintain pressure there is a leak that must be fixed.

Thanks, I appreciate the response. Unfortunately everything points at the heater core. System holds pressure without issue and the coolant level remains steady. No overheating issues either. Just a faint antifreeze odor strictly coming from the HVAC system - recirculating air calling for heat.

Anyway, we'll find out. I've got a dash to remove and evacuate the AC system. Note to self - not in that order.

 

[Jk's97DSM]

Pressure test and pinpoint the leak or leaks before you get into a big job that might not even be the problem. Leaks are leaks.

You could be this deep and not have an issue. This one was obvious, as obvious could be, including a melted flapper door seal from overheating.

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[dwb]

That's not a DSM dash, that's just fear mongering.

You're right, it's worth an hour to pressure test. I'm not confident it will tell me what I don't already know but a pretty easy process nonetheless.

There's a few things inside the dash I'd like to take care of anyway if I go that route - blower doesn't flow great and makes a rattling sound that wasn't fixed with a replacement, the passenger air vent has a broken shutoff, and clutch pedal needs bushings and welded (assuming it will be easier to remove while the dash is out).

 

[steve]

How was the seal on the inlet flapper? I don't know why I didn't see your pictures the first time around but something was leaking and corroding that clip. If it was coolant I'd expect a green or yellow telltail not white unless it was running straight water for coolant.

 

[dwb]

How was the seal on the inlet flapper? I don't know why I didn't see your pictures the first time around but something was leaking and corroding that clip. If it was coolant I'd expect a green or yellow telltail not white unless it was running straight water for coolant.

I can't say I've visually inspected the flapper recently but it does make a pretty good thumping sound and an obvious change between outside air vs recirculate. I have a feeling that clip is rusted from the AC evaporator. I've actually had water drip from the floor vent when it's humid and running the AC. Maybe the drain is clogged? I've never ran anything but antifreeze in the coolant system.

 

[steve]

I've actually had water drip from the floor vent when it's humid and running the AC. Maybe the drain is clogged? I've never ran anything but antifreeze in the coolant system.

That's more likely the cause of the corrosion and buildup.

 

[dwb]

Small update - I fixed the pinhole radiator leak and haven't notice any further antifreeze odor. I've only got it up to temp once so I'll be keeping a nose on it.

 

[dwb]

Small update - I fixed the pinhole radiator leak and haven't notice any further antifreeze odor. I've only got it up to temp once so I'll be keeping a nose on it.

Spoke too soon. Still getting a very faint antifreeze odor briefly when I turn the thermostat to high and engine is fully up to temp. I'll have to see if I can find a rental coolant pressure tester now.

 

[Jk's97DSM]

Again, pressure test the system and if it drops below what you set it at start spraying soapy water on every hose and component to find out what’s leaking. Fix that and pressure test again until it legitimately holds pressure for hours.

 

[dwb]

Again, pressure test the system and if it drops below what you set it at start spraying soapy water on every hose and component to find out what’s leaking. Fix that and pressure test again until it legitimately holds pressure for hours.

Yep, that's my next step. I've never pressure tested the entire coolant system so I'll be researching that. I already tested the radiator on the bench, so at least I know it's good.

 

[Widgmaster]

I had a faint smell of antifreeze in the cabin...it turned out to be the thermostat was not opening correctly.

 

[1990TSIAWDTALON]

Have you added "dye" to the system and used a UV light to look for the leak? You only run the vehicle for a minute or two and then shut it down and scan all areas with a UV light to try and find the source of the leak.

 

[SixBolt_16G]

Have you checked out your hoses and clamps from a position underneath the car? The reason i changed all my hoses recently was because I would smell antifreeze every time i came back from a cruise, but could never find a leak... When I changed out my intercooler piping and was underneath the car putting the new piping together, I saw that what had been happening was that the radiator hose must've been expanding when the car was warm and a bit of antifreeze was seeping past the clamp, rolling down and drying on the underside of the lower radiator hose.. i was getting the smell, but not the visual since it was drying before dripping. When the car cooled off, the hose would tighten back up. Same thing might be happening to you if can smell it but not see it.