Once again my lovely w124 has developed a situatoin even the dealer has trouble diagnosing. so where else but this forum to seek a solution ! :-D
It started last week or so. basically while driving I started to get a headache that I couldn't describe the root cause of. so i opened up the window a little and it felt better. closed the window after a while and the headache was back. so after a little while I figured since the heat is on let me try to shut that off. and there the headache was gone again.
I've figured this much out. as long as the car's vents are being used with fresh air either on heat or cold settings (without a/c) just on the EC mode, something from the vents compartment travels inside the car causing a headache. And to prove that it's not just me I had some friends of mine sit in the car and they complained about the headache as well.
I can't smell any fuel fumes so I'm ruling out fuel leaks. But any idea as to what else could cause this ? I took the car to the dealer, and they were just dumbfounded.
My research tells me that headache is usually caused by carbon monoxide.. question is where to look for such leaks that are only entering the car when the vents are working.... thanks for the help in advance and I really need some advice since I don't want to drive in such cold without heat...

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

Put a carbon monoxide detector in the car to confirm its presence.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

thanks for the reply Kerry,
I've seen CO detectors for home operating on 110V but where do I find the detectors to be used inside the car ? will they be battery operated or run off the car's 12V system ?

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

There are battery operated ones (I have one in my motorhome). I bought it at the local hardwarew store. However, I believe that are pieces of paper with a chemical dot on them that changes color in the presence of carbon monoxide.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

If you are near an airport, swing by the pilot shop where you may find passive units as well as plug ins (to cig lighter). Hmmm, i'll bet a boat shop might have them as well.

__________________
raymond-
47º 34n 122º 18w

A marine store will have or can get 12V CO detectors. Try West Marine. www.westmarine.com

You can get one of those eliminator things that converts 12V to 110V and use a regular plug in type CO detector, if I remember correctly, those detectors are quite pricey.

xp

__________________
1985 190E 2.3L - a constant project.

Thanks guys for the replies. I went to home depot and got a CO detector that works with 3 AA batteries. it was $49 but hey atleast i'll rule this possiblity out. I'll try to put that in the car and leave the car running for a while. I'll keep you guys posted with the results.
Happy new year to all of you.

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

besides putting the CO detector inside the car, should i put it against the engine while running ? will the CO detect leaks like that ? I'm trying to figure out where the fresh air in the vents is sucked in from, because that's where the CO would be coming in from to begin with.
is the exhaust pipe from the engine to the back the only place where CO is present ? any other areas that I should check with the detector ?
thanks.

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

CO is likely the only thing you will encounter with no smell and producing a headache. It is also likely not coming through the vent, but through a floorboard, trunk, etc rust-out or missing drain plug. The vent system in flow through simply helps evacuate the fumes before your symptoms appear. I don't know how likely an exhaust leak into the coolant might be, and if so how it could leak out inside without a significant coolant spray, but if all other sources are eliminated... Check all places where entry could occur with a smoke tester.

Steve

__________________
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

Benz300, You may have a leak in your heater core. The anti-freeze from the heater core may be giving you the headache.Norm in FL

Norm,
thanks for the reply. as much as I would like to be a tech-wannabe, I'm still in the learning phase :-D
could you be kind enough to elaborate on the heater core. what it is, where it's located and how I can check it's proper functionality.
thanks again.

__________________
Whether you think you can or cannot, Either way you're right!. by Henry Ford.

Benz300, Are you loosing any coolant from the radiator? If it is a small leak it could take some time to see it. The heater core is in the A/C duct system . It is a major project to replace it. You should be able to have the cooling sys. cked. for leaks at a dealer or radiator shop. Norm in FL

I can usually smell even minor leaks in a heater core quite easily. Hot antifreeze has a distinctive odor. If the odor is not present, I would suspect another source for the problem.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Here's a long shot - how long have you owned the car? Maybe there is mold somewhere in the duct system causing the headaches. It has been known to cause headaches in households. Maybe there was some water damage from the PO that you don't know about.

__________________
dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles