: Smoke coming out of the vents? That can't be good...

01-06-10, 08:13 PM
Hi guys, I finally got the trans fixed on the '79 Phaeton, and it shifts perfectly. Although now I have another issue. Whenever I drive it, smoke comes out of the air vents all around the dash. A few months ago, I had smoke coming from under the hood, and tracked it down to the heater core leaking a bit of coolant & dripping down onto the exhaust. that still comes & goes, think this could be related? Really don't know what else to say about it, tonight I drove it half a mile to the gas station & back, by the time I got home the interior had a nice haze in it. Pretty much looks like you're smoking a cigarette with the windows up. Just smells like hot dust...

Any ideas?


01-06-10, 08:19 PM
Doesn't smell sweet like burning coolant?

01-06-10, 08:26 PM
First of all, it's good too see you back on here, Ben! Secondly, I'm glad that the Phaeton got it's trans fixed. My guess is that the heater core issue has gotten worse. Is the carpet up under the dash wet? If you put on the defroster, does it fog up/moisten the windshield? Good luck with the old girl!

01-06-10, 09:15 PM
Well, at first I thought it smelled like coolant... although I don't notice it as much now that I moved the jug of coolant out of the back seat (brilliant, I know). I'll have to check on the carpet, the high today was about 35, so that slows the process if debunking down.

P.S. good to see you guys again! It's been too long.


01-06-10, 10:06 PM
Does the fan sound as it should? Something caught in the fan canister could cause a problem. Do you get heat? You could have a problem with the fan's resistor. Sometimes when a car sits, varmits can nest in places and cause and when you start things up stuff happens.
On another note, how did you make out with that red Coupe deVille with the brake problems?

01-07-10, 01:05 AM
Nice to see you again, Ben! Sounds like your heater core leak has gotten worse. Maybe time for a replacement.


01-07-10, 11:10 AM
The quickest way to confirm would be to bypass the heater core, and see if it goes away. If yes, time for a new heater core.

Welcome back, Ben!

01-07-10, 11:35 AM
Nice to see you again, Ben! Sounds like your heater core leak has gotten worse. Maybe time for a replacement.

Craig I agree

01-07-10, 03:29 PM
Ok, how do I bypass the heater core to find out?

01-07-10, 03:45 PM
Take the hoses from the engine to the heater core, disconnect them. Use another piece of hose to connect those two holes without connecting to the heater core.

Someone else can probably help with more specific locations of the heater core though.

01-07-10, 03:53 PM
I guess I just need warmer weather to go out and look it over more thoroughly. Right now I have all wire harnesses I could find going to the heater core unplugged, and that changes nothing. Plus it would be nice to be able to grab a wrench and not have it freeze to my hand, lol. (moved to Chattanooga, no garage right now :()

01-07-10, 04:34 PM
Unplugging wires isn't going to stop the flow of coolant to the core. You need to take the core out of the loop. Just follow the hoses, and take one off and connect it so the coolant bypasses the core. If you want to try a REALLY quick test, clamp down one of the hoses with a pair of vise grips (protect the hose with a rag).

01-07-10, 10:12 PM
The feed hose to your heater core comes off the back of the right cylinder head and attaches to the heater core connector on the firewall. The other hose (return) goes forward to the radiator return port. If the hoses are old, you may have a hard time removing them. Get the engine up to operating temperature before trying to remove the hoses. If they are heated, they should be more pliable than cold.
Don't know what the temperature is in Chattanoga, but today it got up into the low 30's. Felt like a heat wave.

01-07-10, 10:25 PM
Thanks! Now I know what to look for. All I'd found so far was the return hose. I *think* I had the one from the engine replaced about two years ago, so it shouldn't be too bad.

So to bypass it, I could just hook up the one from the engine to the return hose? That sounds easy enough.

Honestly, right now I would like to just bypass the problem, forget the heat, and not have it smoke. A: I almost never drive it in the winter, too much salt. B: Any extra cash I had before just got put into the transmission. C: I'm over having my car in the shop all the time, I haven't taken it for a good drive since mid October. And now with the fresh trans, it's more fun to drive than ever!

01-07-10, 10:30 PM
Ben, Sure miss your sassiness. Come back and play with us more often not just when your car is smoking you out.. :)

01-07-10, 10:52 PM
haha, me? sassy? Never! Sorry I haven't been around more, I miss you guys. That pesky little thing called life keeps getting in the way...damn them and such... The Cadillacs haven't even been getting as much attention lately. Like I said, I moved down to Chattanooga, right now I just have the Phaeton and my '90 down here. The rest of the fleet is still at my parent's house. The '89 I got from Rick (Night Wolf) is in their garage, and gets work done on it every time I visit. Denice (the red '79) made my Dad fall in love with her, now she's his lady on the side.. The '72 Eldorado is just sitting around, I never got to do much work on it at all, still looks pretty much like when I bought it. Probably going to sell it soon, I hate to, but no time & money to make it shine.

Things are starting to calm down, so hopefully I'll be around here promoting dimension IV's & rubbing compound again soon, lol


01-07-10, 11:17 PM
Ben, I always loved you for your bad boy-ness. :) You have a fleet of Cads. You're a one of a kind and an original. Glad you're back in whatever way you contribute. By the way, I LOVE Chattanooga!!! What a pretty city! :) Hope you're driving your Cad every day!!! :)

01-07-10, 11:18 PM
Dave's on a serious posting spree tonight. lol

02-01-10, 03:41 PM
Okay, so, do I need to connect the two hoses accented by the curly thing? or the left curly thing accented hose with the hose by the lowest arrow? Also, what is the function of the little hose by the top arrow? And what does that metal thing it's coming out of do? Sorry, I know that sounded crazy.. Never done heater core work before, And I'm in a coffee fueled cabin fever craze.

Also, what would the the best method of connection?


02-01-10, 04:19 PM
The upper arrow points to a vacuum hose. It's connected to the vacuum module that controls the mix doors that determine how much air flows through the the heater core. The two big hoses encompassed by the fancy bracket thingy are what should be connected to bypass the heater core.

02-01-10, 04:44 PM
Thank you Craig! That's what I thought, but I just wanted to be 100% sure before I started.


02-02-10, 01:35 PM
Done, works fine. Although, does anybody have any ideas for what I could use to plug the holes in the heater core where the hoses went? I rigged something up, but it could be better.


02-02-10, 01:45 PM
I wouldn't do anything drastic. You want to fix it right eventually, so just do anything that seals the holes and holds those two hoses together. That way, when you're ready, you can hook everything back up they way it should be.

02-02-10, 02:40 PM
So that stopped the smoke? Sorry to jump in here, but always interested to read about future problems I might run into. :)

02-02-10, 04:15 PM
Craig, I know that, just trying to think of something a little better than what I have in there now. Like, a rubber hose with the end closed off (auto condom?) lol.

Outsider, yep, that stopped the smoke. No coolant running though the heater core = nothing to smoke... also means no heat though.

How much would a new heater core be installed anyway? I really don't know, just know I didn't have the spare cash when it broke.


02-02-10, 05:29 PM
Couple hundred. What have you got in there now plugging the holes? I was reading in the 1979 FSM and removing and replacing the heater core doesn't sound too hard, just a lot of screws to remove. If you don't have a 1979 FSM, I have one I'm not using (a friend gave me a 1977 FSM), so the 1979 one is yours for the asking. Tried sending you a PM, but your box is full.

02-02-10, 05:44 PM
Thanks for the wonderful offer on the service manual, but I already inherited Rick's from his '79 when I bought the Brougham. Just been thinking about looking through it again actually.

Right now I just have wooden dowels plugging the holes.

P.S. thanks for reminding me I need to clean out my inbox!


02-02-10, 06:08 PM
Wooden dowls work. I was going to suggest rubber stoppers, but same difference. Anyway, I doubt it will be for long. Just need to dissuade unwelcome furry things from taking up residence.