I've recently noticed fumes which smell like CO2 in my car while driving. I'm concerned that carbon monoxide is somehow getting into my car, maybe through the heater. I have a new muffler and exhaust so what is causing this to happen?

Check the rocker covers are not leaking oil onto the heater or exhaust

I had this problem, like really bad. It turned out that the exhaust pipe in the heater box had gotten a hole in it and was blowing the exhast air straight in through the heater. Bloody awful. I just got new heater boxes and the difference is excellent.
Steven

Also check all the heater connections right back to the fan, and make sure the corrugated hoses are in good nick.

If you've just put a new exhaust and muffler on, I think the smell you notice is probably just the paint burning off the new parts. This happens even when you use hight-temp or pot-belly stove paint. It always burns off. Last time I painted mine, the burning smell lasted a week or so.

VW heaters always smell a bit enginey - it's one of their endearing characteristics. But does your heater actually smell like exhaust, or just hot engine?

You can't actually smell carbon monoxide - it's an odourless gas.

The other thing to check is the crap slip joint where your muffler joints the heater box. Pots 1 and 3
The BEST and ONLY way to properly fix it is with a flange kit.
You might have to have the motor out - certaily would want it on a hoist.
They put 2 flanges (like the size that joins pot 2 and 4) on and weld them in place. You use a gasket and bolt them together.
NO LEAKS
My heater is perfect after 20 years of owning the things.
If i had to list a mandatory modification inclusion to all motor rebuilds this would be it.
Costs peanuts but the pleaseure gained is immeasurable!

This is the way Porsche did it.
IT SHOULD HAVE BEEN DONE THAT WAY IN THE FIRST PLACE MR VW!!!

Bottom line: if your car smells the same inside as it does behind the exhaust outside, then its a problem.
I had this problem with leaky internal piping in my heater boxes aswell, it just smelled like exhaust inside, especially when I blipped it.. I just replaced the boxes with ones in good nick. It was frickin hard with the engine still in!(that darn top exhaust flange nut!)

Josh.

Phil74Camper my heater smells like exhaust. I can smell it on my cloths and I sometimes get a sore throat from the fumes. :puke

What makes the situation worse is that my heater is permanently on. The wire connected to the right hand lever was too short, so it's on all the time. All I can do is close off the vents.

I realise you can't smell carbon monoxide that's why I'm worried it could be entering without me even knowing it.

Thanks guys for your tips. I think I'll pay for an expert to check it over and fix it. I'll let you know what the problem was.

:puke:puke

One of the problems with a leaking exhaust or heat exchangers is that carbon monoxide (CO) attaches itself to the haemoglobin (?) in your blood about 400 times more readily than oxygen.

But wait there's more

It's build-up is cumulative. So it may not get you today, or even next week. But sooner or later as the CO levels rise it may only take a short trip to the shops and WHAM, you're a gonna.

One method of treating it is in a hyperbaric chamber to dislodge the CO and replace it with oxygen.

I will definitely be doing that blue, I'll just have to put up with the cold, a safer option than being gased!:o