TheExaminer

Some of you may have seen my "oily fog on the windshield" thread from last week. Tried to post again there and no one responds. To make it short, I had the HC replaced 18 mo's ago, and this May my windshield started fogging up on an 85 degree day, so I thought I'd go ahead and replace the crappy aluminum one the shop put in for a brass copper. But now I'm having the same issue again! I bypassed the HC this week to see if that made any difference, and when I started it up yesterday to come home from work, FOG!! It never does it on the way TO work, only after its sat in the parking lot all day and been re-started. There's always one blast of it as soon as you crank the engine, then it doesn't fog any more all the way home. And btw, the temp slider is always set to cool, I don't know if it would do it if set to full hot.

One thought I had was that there was a leak in the stand pipe/hose connection at the heater core--which is right above the exhaust. I thought it might be leaking down as the car cooled, dripping near the cats, and creating a little vapor cloud under the hood near the firewall that got sucked into the air duct plenum when the motor fired, and thence to the glass. I don't even know if that's possible, but either way I can feel no leak there, and I just did a pressure test. As long as I held the tester still, it held pressure perfectly! (With the HC still bypassed). Another thought was that since the heater core pipes were disconnected and still with coolant in them, maybe THEY dropped coolant onto the exhaust and etc. But if that's the case, why was it fogging up when the core was still connected?

The evaporator is still in the car, but the AC system is empty. I'm going to drive it next week with the HC completely out of the car, and if it still fogs up, then I'll remove the evaporator completely. But I can see no evidence whatsoever of a HC leak in this car. The core was dry when I pulled it, and the area it sits in was just as clean as it was when I cleaned it out last month, except for a little random dust. Where is this fog coming from? What is it? And why only after its gone through a heat cycle? And why only briefly at restart then nothing else all the way home? Never does it until after you stop and restart hours later. HELP!

t-top havoc

iTrader: (3)

Bypassed heater core?
Did you find a wet carpet at any time?
I have no experience with A / C doing that kind of thing, it never worked in any of my cars.

TheExaminer

Nope. No moisture in the interior of any kind that I could see, or anywhere in the hvac box. I just used a fitting to connect to two HC hoses and left the core sitting there. When it failed the first time back in Feb of 14, it basically exploded and soaked the carpet and hvac. But that's long since been cleaned up, and it just now in May started fogging up. New brass copper put in last month, and fogging up again within 3-4 weeks, and fogged up even with that brass copper totally bypassed. Fortunately for me, it only takes a few minutes to get my HC out, so it's more of an annoyance than a major issue. Still, want to get it figured out. It's getting to be a pain.

ryanz281988

That happened to me the carpet under my passenger side dash area was wet found out it was the heater core. But before all that my window was fogging up all the time until I sat in my passenger seat and ended up with coolent all over my shoe lol.

So I changed the heater core and no problems since.

TheExaminer

UPDATE:

Bypassed heater core--no fog on the drive to work, go out to start it after work, a quick burst of fog, then nothing.

Removed heater core from car entirely--Same result.

Removed evaporator from car--same result.

Reconnected heater core--same result.

Pressure test--held pressure perfectly as long as I held the tester still.

Added UV to coolant--checked for leaks, found NONE that I could see. No evidence of coolant on heater core or in hvac box or passages.

What is on my windshield guys, and where is it coming from? All these thirdgen geniuses and no one with any ideas?

mustangman65_79

Someone at work screwing with you?

TheExaminer

Normally I would laugh at this--it IS a good joke--but I'm so sick of trying to figure this out, I'm hoping for something more helpful. But no, no one is screwing with me at work. The people I work with don't know enough about cars to be able to do that. Thx anyway...lol

-=Z28=-

iTrader: (3)

Those HC's are very brittle where the lines are soldered in. I bet when you installed it, one of the soldered connections got reefed up and sprung a tiny leak. It doesn't do it in the morning cause all the pressure has gone and dripped clean. when you go to work, pressure builds, leaking a little, but has not dropped off the HC. when you hop in after work and turn it on, poof, the fan launches the droplets,mist onto your windshield.

I had the same prob. I had my radiator shop guy beef up the solder connections and the problem was fixed.

Pressure test the HC and see if it leaks.

-Dan

TheExaminer

The trouble with that is, as I said above, I bypassed the HC and still had the same issue. I then completely removed the HC from the car and it STILL did it! It also did this with a previous core that was only a few months old. I'd like to pressure test the core itself outside the car, but how do you do that?

-=Z28=-

iTrader: (3)

yeah, I kinda ripped through the replys.

Taste it next time. Is it sweet like antifreeze? You say "oily", there is only a few oily fluids in the car. Take a sample and bring it to the science lab at your local University...

-=Z28=-

iTrader: (3)

You either have something that is still wet someplace, or a leak.

How about take the hc out and leave it out for 2 weeks. see what happens.

What is the inside temp of the car when you park it? sun/shade? bet sun.
What is the temp outside when it is doing it? hot? i bet.

Is the fog patch the same size or does it change?

Are your drains plugged in/under the firewall? (under the wipers.)

3 min to get hc out??? this cant be a 3rd gen...

TheExaminer

Ok, I'll go pint by point....

I didn't ever see any wet spots or evidences of leaks when I took the HC out. Everything perfectly dry in there. Just random dust since I cleaned it when I first put this HC in first week of July.

I could take it out for two weeks, that's an option. Had it out for about a week and was still getting fog at restart after sitting for hours.

It's always a hot sunny day. Has been every time, and the car is always parked in direct sun all day at work. Now Friday I drove all the way to work with the heat on to test it,and it was a chill morning. Had the same fogging trouble at restart, but on other days I've left the slider on cool and it's still done it.

The fog patch always rises up in the general shape of the defrost vents. One day I took the dash pad off and taped the vents shut, and fog still rose above the vents. That's not definitive though, because I doubt all that is perfectly sealed after 23 years.

Drain plugs under the wipers? That's interesting, I haven't checked that. I'm going to soon though, because I'm planning to pull the wipers to paint them, and clean/paint the area around the air duct outside plenum.

Yeah it's a thirdgen, I'm just quick at getting the HC out. Since it's a Firebird, all I do is pull the map pocket off, and there's a hole drilled behind there that's right in front of the hvac top screw, (pictured below) I can literally have the HC out in 15 minutes max. Taking off trim pieces and draining the coolant is the hardest part. And like I said in a thread a few months ago, in Feb of 14, I paid some clown $540 to change the HC out for me, and it took him over 7 hours because he did it "by the book" and took the entire dash and console out!

TheExaminer

LOL.... I wish. Anyway, I've had that idea and tried it, but there is so little of it it's hard. Honestly, less than a drip could do this and cover the windshield with that fog. I tried scraping a bunch of it up on a paper towel and tasting it, but no taste yet. I'll try it again. But it won't evaporate, you have to use windex to clean it off. Now that it has the UV in it, I tried shining the uv light on it last night after dark, it sort of glowed, but it was hard to say if it was just a trick of the light. Was not definitive. I'm going to put a little water on a towel, try to wipe up as much as I can and see if there is any taste.

-=Z28=-

iTrader: (3)

How many licks does it take to figure out whats on my windshield??? lol

Your neighbor sees you in your car licking your windshield.....
"What has gotten into that boy?" "Honey, come look at the neighbor, I thing he's lost it this time!!"

LOL

-D

TheExaminer

LOL it would be easier if I could get my head down in there. I took a pt and wiped all across it to scrape up as much as I could, but it's tough to get any taste. I THINK it might have had a sort of sweet taste, but it's tough to say. It's probably coolant. BTW, what do you guys think of the idea of it dripping on exhaust or something during cool down somewhere below the firewall, then getting sucked into the air ducts at startup?

Joe Tag

iTrader: (4)

Did you pull the carpet back on the passenger side and check under it for a puddle still not dried up? The carpet is rubber backed and can be sopping wet underneath and feel dry on top.

TheExaminer

Oh yeah, the carpet was soaked when the original HC failed in Feb of 14. I got so sick of the smell I pulled back the carpet and removed the backing, which was also soaked. I then wiped it all up and cleaned the carpet, there's not much if any smell of coolant in the interior. Then when I replaced the HC in July I cleaned all the passages I could clean, which basically consisted of the main HC housing since everything was still assembled. Even then I didn't see anything wet in there, just dust and dry residue from the other failure. But keep in mind, this current set of incidents was 17 months after the initial HC failure, and I had no fogging issues until this past May. A hot day in May is when it all started.

TheExaminer

Stopped at the Chevy dealership today to pick their brain. Tech there said to check the plenum drains and etc, as stated above, and also presented the idea that some of the foam inside the passages may have some coolant in it. Could be, might explain why it always fogs up on hot, sunny days. I didn't see any, but didn't feel every nook in there either. It's possible. I'll know more when I get my wiper arm puller and yank all that stuff off the plenum.

hectre13

iTrader: (4)

so, not sure about the oilyness, but this kinda happens in my wifes car, and was because she left her sun roof open and got rained in, now she randomly gets foggy windows on the inside of her car, my guess is that you have a leak somewhere that has soaked into your carpet (leaky t-top maybe?) and when it gets hot it evaporates and gets moisture on the windows?

next time you goto work, leave the windows cracked and see what happens.

TheExaminer

Nope, it's not water. You have to use windex to clean it off. As far as I know my tops don't leak, besides, I never drive this car in the rain anyway. Only on sunny or dry days. This fog actually comes up out of the defroster area when I restart the motor after sitting all day at work. Never in the morning, never while I'm driving. Only at restart after sitting in the sun.

greenyone

iTrader: (1)

Have you tried taking off the evap core box to see if there is anything in there. Maybe some residual ester oil from a leaking evap core is causing your problem.

TheExaminer

Yeah, thought of that. AC system is empty, I even removed the evaporator, and it still fogged up with the evap completely out of the car.

greenyone

iTrader: (1)

That would drive me crazy too. There has to be some residual phooey in the duct work. Short of taking it all apart for cleaning...maybe you can try and dry it out. How about popping off the blower motor and running a hair dryer through blower motor hole? Run it on low heat (or high) until you burn out the coils of the wifes hair dryer.

TheExaminer

Well, like the guy at Chevy said today, could be some damp foam in there, but I checked today and didn't find any. I had the blower motor off last week because I put a new one in. No way I'm taking the entire dash apart to clean it. LOL Another thing I noticed was that after I drove it to town today, and brought it home it didn't fog up at restart after it was parked in the shade under the carport. Hmmmmm...

eseibel67

I think this is it. Carpet and backing can hold A LOT of liquid, even if you think it's dry. And the water (antifreeze) can wick aft under the seat where you won't notice it. The car sitting in the hot sun will help to dry it, but it will take forever. I would completely remove the carpet and leave it outside in the blasting hot sun for a couple of days.

TheExaminer

^^^^This question has already been answered above. This is not the issue. The original HC failure that soaked the carpet was in Feb of 14. I already dried the carpet, pulled the backing out and etc. Besides, it wouldn't go for 15 months without causing a problem, then all the sudden start for no reason. Plus, when I changed this last HC out in July, the hvac box wasn't even wet, let alone the carpet.

TheExaminer

Latest: Today I parked the car facing away from the sun, and put a towel on the dash pad. When I started back up, very little if any fog at all. Tomorrow I'm going to do the same thing without the towel and see what happens. If it does the same thing, almost certain confirmation that somewhere in the passages there is residual coolant from the failure in May that I haven't found yet. Just have to figure out where....