After 449K miles, is this how my '80 245 DL ends?

Driving into school this morning, I started getting some sort of mist/steam that came through the vents, and through the windshield defroster vents. Temp set to full Cold (as far to the left as it will go).

This "mist" left some particularly nasty "fog" on the inside of the window. It leaves a "foggy" residue on the window (which oddly enough did a good job of removing some adhesive that was stuck on the glass from a parking sticker.) It would not just "melt away" like it usually would (I had the window down full).

I tried turning the heater control knob to hot and warm settings, but it didn't seem to make much of a difference. Maybe the hotter settings made more fog in the car, but I was trying to pay attention to the road which was somewhat difficult.

Once I jumped on the freeway, that's when the fog started pouring out of the vents.

What should I do?

If this is the heater core, it may be the final nail in the coffin of my beloved wagon. As it is right now, the steering column is shot. A fender needs replacing. The electrical system is still being funky and I can't figure out why. Problems seem to be adding up, and time is something I really can't spare these days (main reason I don't frequent this forum as much as I use to.)

I've done the heater fan in this car, but as far as I can tell, doing the heater core is a lot bigger of a task.

Is there anything else this could be?

Thanks as always.

Lick the inside of your glass. (It won't kill you.)

Sweet? Coolant.

Not? Well...

OK, you can also swipe the glass with your finger and put it to the front part of your tongue.

I did this in a driveway last summer. The stuff was green, but not sweet. Started to gather it was probably part of some A/C work. The car's owner was kinda stunned by the tongue action, but so it goes. ;-)
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Gregg Shadduck, Mpls, MN -- 2x '87 745; '92 245; '67 Amazon

You almost certainly have a leak in the heater system. If the mist on the windows has a "greasy" feel - that confirms it, it's Glycol. The leak could be enough to create the fog, but in a short time, not be evident as a drop in coolant level in the reservoir.

Start with the simple checks - pull the driver's side console panel and check around the heater valve. Then remove (easy job on your '80) the upper dash storage bin and use a strong flashlight to view the heater hoses where they connect to the core. Maybe you can get a hand in there to feel for dampness at the connections. If everything so far is dry, it's hard to see how the leak can be other than in the core. Yeah - a real chore to R&R - we did my son's last February.
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Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, 94-944 B230FD; hobbycar 77 MGB, and a few old motorcycles)

Any tips for doing the job? I'm probably going to need them.

If you can smell antifreeze, it is either the heater core or a leak where the hoses plug on to the heater core at the firewall. You don't want to tear in to the heater core only to discover that it was the hose connections.

If there is no smell, you could have a plugged or pinched drain under the A/C evaporator. I think you can get to that by pulling the sides off under the dash center. You might be able to poke a wire up it from under the car if you can figure out where it comes out under there.

If it is the heater core and the car is on it's last legs anyway, try some radiator sealant as a temporary fix. You might get another year or two out of it. You can also just disconnect the hoses from it and run without a heater if you live in a warm dry climate and don't need to de-ice the windshield.

How would I go about bypassing the heater core temporarily? I will certainly need heat in the car before December rolls around, but I may be able to do with out it until Thanksgiving weekend (when I should have enough time off to take on this task.)

Parts stores generally carry some heater hose block off caps, a set of rubber caps, you remove the heater hoses at the block and put the caps on with hose clamps
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '82 Mercedes 300SD for sale

Heater control valve is also a possibility, but most likely the heater core if you've got mist from the vents.
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Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina

if it were the heater core you would be loosing coolant, and you would smell coolant inside the car ( kind of a sick-sweet smell ).

Did you have the AC on? was the temp outside mild to cool with high humidity?
If so the AC may have just been icing a bit.
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '82 Mercedes 300SD for sale

The AC in the car has been inactive since it came into the family in '87. It was cool out side (not freezing) but there wasn't much humidity at all. (I ended up rolling the window down in hopes it would suck some of the mist out.)