Well, I drove out an hour to CT tonight to pick up a baby crib. I had some twine and bungee cords ready to tie down the hatch. It was a nice night for a drive, crisp, not too congested.

After piling in the crib parts, I was wondering where to tie it down. I ended up tying the hatch latch hook to the tow hook.



Some things I learned driving back. If I went over 50mph the hatch would start rising up. I thought I would have to pull over and tie it down more tightly, but then I tried venting the sunroof and the hatch came down snugly against my cargo. I guess it's that physics principle about high/low pressure areas created by the wind flow?

I drove cautiously back, pretty much trying to flow smoothly in the right lane. I felt like an injured animal, but to make it more interesting I stared at the real-time MPG display in a first attempt at "hypermiling". I got 50.4 mpg versus the 33.3 mpg going there. Not sure if I would do it again if I wasn't forced to. Gas prices are going down.

 

Did you get drowsy from the carbon monoxide poisoning?

 

lolwut?

I'm pretty sure the car was moving for some of the trip between two points.

 

Feeling a little tired today? Maybe catch yourself yawning or taking a deep breath now and again?
I recommend a good, rare steak and a nice spinach salad. Drink some orange juice, too. You need iron and vitamin C.
You just wiped out a bunch of red blood cells with CO2. Don't fool yourself into thinking it takes a bunch of exhaust to do damage. 4% is the maximum exposure limit under OSHA (15 minute exposure, IDLH). 5% is directly toxic.

Never ride with an open hatch. Oh, and opening the sunroof sucked it down, but not closed. So you have this vacuum pulling down on the hatch and sucking all your exhaust in with it. Nice.

Don't sweat it. The effects are short term. If you live, you recover quickly.

 

Not sure how you can diagnose carbon monoxide poisoning based on the OP post. I frequently haul long items in my Clubman be simply keeping one or both rear barn doors open. I also keep both front windows open, and the sunroof open, as well. As long as there's plenty of fresh air coming in the front of the car, I think your concerns are overblown.

 

There really isn't fresh air coming in the car. With the hatch open the car is creating a plenum chamber. An exhaust and ambient air mixture are being sucked in thru the open rear hatch. The OP pointed out the hatch stayed down when he open the sunroof. It is not something new. Its been around since they started putting glass in the windows.
I am not being snarky. This is a common enough issue that they put warnings in manuals and warning labels on more than a few models of cars trying to prevent it. How far you drive and how efficient your engine is determines how much CO2 you get.
Driving with the rear hatch open is like idling in a garage with the door closed. Same effect.

 

Doh! Thanks for the insight. I definitely need that warning label. Could have been ugly. Next time I'm renting a U-haul.

 

Except that in a closed garage, the CO levels in the garage will continue to rise virtually without limit over time, whereas the CO level in a moving car will reach equilibrium almost immediately, with the level in the car determined by the ratio of exhaust gas to ambient air being pulled in through the hatch.

That being said, it doesn't take much CO to be harmful/fatal. An atmospheric CO concentration as low as 0.05% can be fatal, and car exhaust can easily contain 1-2% CO. so, unless you're positive that the exhaust gas is being diluted more than 40:1 by the ambient air before being sucked into the open hatch, I don't think it's a good idea to drive around with the hatch open.

 

 

I'm still waiting for my MCS (about two more weeks to go), but I know when I have to drive my wife's minivan with the back hatch open I put the A/C and/or vents on high to basically create positive pressure and hence keep the exhaust out.

But I agree that one must be very careful and in general it is a dangerous activity.

 

I've always hooked the bungee cord to one of the tie-downs in the boot. I suppose it depends what you are carrying and how long one's trip is. I was just going down the street.

 

Yes - if the hatch is open, but you have all of the windows/sunroof closed, the low-pressure area behind the car keeps the air flowing front-to-back. That's why the the hatch in lacning74's car would try to open up when he was driving 50+ MPH.

But if you open up the sunroof or the side windows, the airflow around the car produces low-pressure areas near the open window or sunroof that are actually lower-pressure than the back of the car, so the air gets pulled back-to-front through the open hatch, which is why his hatch stopped lifting at speed once he opened the sunroof.

In the plane I fly for the Navy, there are two overhead escape hatches up front, one overhead hatch in the rear, and the main door in the middle. When the designers were coming up with the emergency procedures in case of a fire in the plane, they flew the plane in all possible hatch configurations, using a tennis racket with a bunch of threads tied to it to measure which way the air flowed in the plane. They found that if the pilots up front opened up both of their front hatches, and the rear hatch was also open, the air in the fuselage actually got sucked forward into the cockpit (even with the cockpit door closed), unless the main entrance hatch was opened as well.

 

you people crack me up.....Its like none of you CO2phobes have ever driven something line a 78 monte carlo with dual exhaust pipes right beneath the rusted through floor boards....I have owned several late 70's or 80's pieces of crap that you drive and all your clothes smell of exhaust gas. people are little paranoid these days

 

I'd be more willing to laugh it off if carbon monoxide weren't the cause for most fatal poisonings in the world. Granted, most of those cases are from household appliances in enclosed spaces, but it takes such a small level of CO to be dangerous that it seems a silly thing to risk.

 

Not paranoid, more like informed. I carry a MultiRAE unit on chemical spill responses. They take a few minutes to start up, so we fire them up on the way to the scene. You would be surprised how much CO2 your driving through in heavy traffic. Turn the a/c to outside air and watch the percentage climb.
I have never driven with the back doors open while carrying the MultiRAE. Some theories do not require testing.
You are prolly not going to kill over from driving around the block with the hatch open, but that doesn't mean it doesn't cause damage.
Motor on.

 

Is the MultiRAE measuring carbon monoxide or CO2? I've seen "CO2" thrown around a lot in the thread, but I think we're all talking about carbon monoxide, not carbon dioxide.

 

Yeah... it isn't that bad. I'd be more afraid of the CO than the CO2 that 4xAAAA was talking about, but I've seen horrific rides that should be more worried about exhaust than a quick trip to pick up a crib. I mean, come on...

That would be like saying, "Don't walk outside when it's thundering or you have a high chance of getting struck by lightning," or, "If you drive to the store, you will get in a car accident and die! Better take some pain killers before you go!"

On second though, pain killers might be a good idea...

 

Oxybluecoop, Your funny!!

 

Very interesting thread about the airflow and pressures. It would be interesting to test it out like they did in Scott Riqui's jet and see how you could get the airflow to go out the back and not intice CO to flow into the open hatch to the cockpit. You could test it with a CO meter as well. I imaging there's a way to minimize or possible eliminate significant CO contamination in a moving car with the hatch cracked if there were an emergency need for it (short of opening all windows/sunroof of course).

 

I think I remember reading somewhere that the red blood cells will take up carbon monoxide more readily than oxygen. And I know that even with windows/hatches open, the back of a car (especially a 'hatchback' configuration) is going to be a low-pressure area - essentially a vacuum cleaner - that will pull whatever into the car. The back of the car is where the engine dumps it's nasties. So why go out of your way to kill brain cells? It's happening at a pretty regular basis as it is, no sense in hurrying things along if you can avoid it.

 

DOH! CO...CO2.

Ispell wasn't gonna help with that.
Just ignore the errant 2s.

Thanks for the spot Scotti. Dead on.

 

...some theories don't require testing??? All theories require testing, that's how theories are confirmed. I think it's just nonsense that my Clubman will fill up with CO even if I have all the windows, and the sunroof open. I can feel the wind coming INTO the car through the front windows, not blowing OUT. I'm glad you have lots of high-tech equipment you apparently use in your job, but until you put that equipment in the front seat of a moving Clubman with all the windows open, and take a reading, you're theory is simply your opinion.

 

Point well made, Miniclubman, but I will pass. I think there is enough information out there on the subject already.

 

You know, from aeromed classes I learned that it isn't asphyxiation that is the biggest factor here, it's the mental impairment that comes from milder exposure. You think you're OK, but you do dumb things. Like buzz driving. Slow brain function. If nothing demands much thought, you get along fine. Let some jerk wander into your lane or run a light and --oops--you weren't paying attention.

I've sucked a lot of pure O2 waiting on the ramp or taxiway to avoid that little trap. One whiff of exhaust and I was on oxygen. We'll never know if I was prudent or paranoid since I never had an accident.

But I do know this, I'm not abandoning that caution just because my MINI doesn't have real wings and an empanage.

 

Whoa.... that's heavy duty. I just take a hit of coffee from my travel mug.