headache....
 

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...

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

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 ?

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.

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.

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

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.

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.

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

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.

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.

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.

mold doesnt seem to be the issue.
as for the coolant leaks i'll check the level, though i have to say that i havent smelled any coolant inside the vehicle at all...
I'm driving the car with the CO detector inside and so far the readings are coming out to be normal...

Headaches
 

Coolant could very well be outgassing from a simple small leak that has not developed into a noticable leak yet (dampness around a hose fitting) so don't rule this one out yet. You could try to disconnect the heater hose from the aux. water pump and ride without the heat (using a 12v electrical heater) to confirm or deny this as the culprit.

This case reminds me of the Army brass at Ft. Benning that had his engine replaced in his Cadilac. When he got the car back, he started to smell a foul odor, and couldn't find the cause. Since he car-pooled (and drove his Caddy) each morning he would have a car load riding to the base with the windows down, and it was winter time (cold, but in Georgia). His wife told him to sell it or she would not ride in it anymore.

He took it to a car wash and they removed the back seat looking for the cause, and found a dead mouse that had crwaled into the car and died while having the engine replaced in the shop. The Caddy had leather interior, which is pourous, so the stink was aweful, even after two trips to the car wash at $200! I could hardly stand smelling it before I placed my air purifier in it, and the windows had been down all day! So, the army brass told me that if my machine worked, he would buy one for his home. It worked, but he didn't make a purchase, because the problem was gone.....that's how the government works sometimes, huh?

Hope you locate your source of headaches. It seems to be air related.

I'll look for small leaks of coolant again. My only question is... wouldn't I smell the coolant if it's fumes were entering the cabin causing a headache ? I'm assuming the fumes would carry the coolant odor as well... the car is using the green stuff, not the original mercedes coolant. And I can certainly tell the smell of the green coolant

Maybe the smell is so slight that you are used to it. Have somebody who hasn't been in the car for awhile ride in it and see if they smell anything. Coolent you should smell. Leaks should be easy to spot. Gunk the engine and clean it real well to remove coolent any that may have been spilled. Good luck.

Is the A/C system still charged? Maybe it is R134 or R12 slowly leaking out and into the vents. Long shot.

This is a serious problem so be careful and drive with your window open unitl it is solved. I think you are on the right track with the CO from the exhaust. I've had coolant leaks that you definately can smell and I don't recall getting a headache. The detector is a good first step but it may not be sensitive enough to trigger the alarm.

Is there any way to have someone (midas, carx, etc..) pressurize the exhaust system all the way through the exhaust manifold and check for leaks. I would think that this has been done before.

If the exhaust is OK maybe there is a dead cat in your air intake.

Headache
 

Either way, coolant off-gassing would be hard to smell, unless you had the nose of a k-9. Small amounts of coolant off-gassing could not be detected by your sense of smell, while causing a headache.

The problem seems to be related within the air stream, and if it is not coolant, refrigerant or any other off-gassing, the only other thing I could think of is ionization. Positive ionization causes headaches, and they are termed "ill winds", and in some parts of the desert in the Middle East, the suicide rate is incredible when positive ionization is found in abundance. If you have an electrical component that is somehow spraying positive ionization into the air stream, this could possibly cause the headaches. I know it may be difficult to determine, but if you take a look around in the dark with the engine running, you may find some sparks or signs of a switch or other electrical component showing signs of failure.

Negative ionization removes the headache, and actually stimulates the central nervous system, and is used in hospital to treat burn patients, since it promotes skin healing at an advanced rate.

This is just something to consider, so if you don't locate any leaks, it may be positive ionization in the air stream. Have you confirmed or denied the coolant issue with disconnecting the heater hose connection from the engine yet? It is worth a shot.

Hope you discover the issue, and when you do, please let all of us know. I know what I make mention of here is a long shot, but since you're still fishing for the cause, I thought to let you know of what I had in mind, since I have studied ionization extensively over the past 13 years. It is a mind opening experience to discover what your indoor environment can hold for you. Even mold, in the early stages is not detected by your sence of smell, and can cause severe headaches and black lung disease.

Hey, I just thought of a way to confirm or deny if it's air-stream related. If you have access to an expensice resperator that would protect from carbon monoxide and other gasses, try wearing it while driving, although I would do this test at night when no one could see what you are doing :D.

Also, have you conducted a search in your interior? Like removing the back seat, looking under the front seats, glove box and elsewhere? Even spilled liquids that have dried (such as dry-cleaning fluids) can still out-gass and cause headaches. I am very sensitive to those cleaning agents. Even some bar soaps cause me a minor skin irration.....(Ivory has been the best for me :))

Hope this helps.

dtf,
you bring on an interesting point. the r12 was infact leaking because my car was in for service just last week to have the compressor changed. They changed it after they found that the R12 was leaking. that however has been fixed at this point.
I've been driving the car for two days now ever since it came back from the dealer for the r12 leak fix. The CO detector is giving out normal readings. I've placed the CO sensor at various locations to make sure I dont leave any spot inside the car.
It's been raining here in NJ all past week so I can't really open to hood to find out coolant leaks since it'll be hard to spot them in such heavy rain :)
I will keep you guys posted.
thanks again for everyone's posts and helpful hints.
happy new year to everyone.

allright here are some updates....
I went for a long drive tonight to figure out what exactly is going on. the CO detector showed normal readings through out the drive. here's what I found. the cause of the headache is the heat.. not the vents or the air from outside. with the temp to the heating level, it feels as if someone has sucked the fresh air out all together and I need to open up the windows to breathe. but when I turn the knob to cold temp everything is perfectly fine. I tried it with both on the e/c mode and also with the A/C on in both hot and cold levels. same thing. when the hot air blows through the vents it brings along headache...
I tried to smell the antifreeze but couldn't. the coolant level is perfect as well.
Here are the questions :
with the heater on, are all the vents for cold air closed or is the fresh air mixed with the heated air and then blown in through the vents ?
secondly, what's the path that the hot air takes starting from the front of the car all the way into the vents... because obviously somewhere along that path is where the problem lies...
I'll wait for everyone's replies..
thanks !

Still Online?
 

If you are still online, I just sent you a PM.....need your email address to send you some PDF files.....and which car are you working on again?

ok guys,
I'm not sure the two problems are related or not. but my vacuum actuators are acting up meaning i'm having problems with heat / cold climate controls. I had posted that issue right before the car went in for the service of A/C freon etc.
The dealer has told me that I'll have to replace the vacuum actuators, all six and quoted 9 hours just for labor. ahem !
the question is, does that somehow translate into fresh air not being able to be supplied to the cabin while the heat is on, resulting in loss of fresh air ( thats if there is such a concept of fresh air coming in as well while heat is on) and resulting in headaches due to lack of fresh air ?
the reason i ask is because with the heater off, and the vents on just for cold air there are no headaches.
the center vents aren't working while on the cold temp setting but then again that I know is because of the vacuum actuators....
any ideas ?

Excess CO2 will cause headaches too I think. Maybe you aren't getting fresh air like you're suggesting or even maybe the recirculating part of the climate control is stuck on 'cabin' not allowing fresh air in. I am not familair with the vaccuum actuators or their mechanics. Sounds like you are getting close though.

I was searching through the posts and came up with a lot of posts where the center vents stopped working in the heating system. However I didn't read any of the posts complaining of headaches while the vents were not working properly.
can someone shed some light on this ?
thanks.

I'm only familiar with the heating system on a 123 so take my ideas with a grain of salt. In a 123, a vacuum actuator permits fresh air to enter. I don't know the exact relationship to the center vents but it seems to me quite possible that if the actuator for the vents is bad, the actuator for the fresh air could be bad also. The way to tell is to identify it, and pull a vacuum on it.

when the heater is ON, does all the air coming into the cabin travel through the heater core, or is there another vent that lets the air in through another channel at the same time ?

anyone ?

Benz300, Just another thought. The vent system in these cars goes out througt the trunk. If there is no fresh air coming in the front through the vents. the exit vents may drawing exhaust in. These vents have a flap so air should only go out. Just a thought. Norm in FL

Norm

I think that is a great point. Also I have noticed these flaps get old and just don't work the way they were designed to.

Haasman

Temp. of Heat?
 

Seems like you have figured out the cause, but have you thought of the solution? Heat temp. too high? What is your highest heat temp. while going for a long drive?

A thought triggered by the cabin-vent-flap post: What happens on AC when you hit the recirc button?
I'm still looking at exhaust as the most likely culprit, given the known characteristics of CO. Have had a coolant leak into the heater core, and in that particular case there was not only a noticeable odor, but a film developing on the inside glass ('99 Saab in a Michigan winter).

Well,
there's no odor even the slightest inside the cabin that would indicate the coolant leak. however possbile. But as indicated by some other posts there's no sign of a film buildup on the windscreen either. I double checked.
the heat that I kept the car on was at 70 to 75 just when the flaps flip and the heater kicked in. nothing too high at all.
as for the exhaust coming in, are we suggesting that the ventilation is proper when the temp is set at cold and as soon as the temp control is set to high, the heater kicks in the ventilation becomes all tangled up letting the exhaust fumes from the trunk inside the cabin somehow ?
THe reason I'm stuck with doing this myself is because the dealer is dumbfounded. their only suggestion was they want to throw a 1500 bill towards me to fix the vacuum actuators first and then look at something else. which is ridiculous because after fixing all that if they say they have to tackle the heater core they'll charge me for another 18 hours of labor to open the whole damn dash again. And i'm not ready to spend another 4K on a car that i've already spent almost 7K on. and at the end the car's resale value will never exceed 5500 to begin with.

Vacuum actuators
 

Hi there, just a thought, get your hands on a vacuum line diagram showing the complete vacuum schematic relating to the climate control system.

Trace (check for) vacuum present starting at the source, then step by step through the system.

Your problem could be as simple as a vacuum leak or faulty vacuum switchover valve.

Acky